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Q&A LM5069 hot-swap circuit for 48 V

Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, and the time to blow the fuse is longer than timescales of the semiconductors...

posted 10mo ago by Pete W‭  ·  edited 10mo ago by Pete W‭

Answer
#9: Post edited by user avatar Pete W‭ · 2025-11-21T02:29:50Z (10 months ago)
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. Actual current when blowing higher. The use of the fuse would be to protect battery from shorting into a damaged circuit.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives V*I wattage at 1A: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside. Also take into account if circuit lives in an unventilated enclosure, or even a controls cabinet, these are above ambient.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd feel better with 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, and the time to blow the fuse is longer than timescales of the semiconductors. Peak current while blowing higher than 3A also. The use of the fuse would be to protect battery from shorting into a damaged circuit.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives V*I wattage at 1A: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside. Also take into account if circuit lives in an unventilated enclosure, or even a controls cabinet, these are above ambient.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd feel better with 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
#8: Post edited by user avatar Pete W‭ · 2025-11-21T02:27:49Z (10 months ago)
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. Actual current when blowing higher. The use of the fuse would be to protect battery from shorting into a damaged circuit.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives V*I wattage at 1A: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside. Also take into account if circuit lives in an unventilated enclosure, or even a controls cabinet, these are above ambient.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd feel better with 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. Actual current when blowing higher. The use of the fuse would be to protect battery from shorting into a damaged circuit.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives V*I wattage at 1A: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside. Also take into account if circuit lives in an unventilated enclosure, or even a controls cabinet, these are above ambient.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd feel better with 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
#7: Post edited by user avatar Pete W‭ · 2025-11-21T02:25:42Z (10 months ago)
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. Actual current when blowing higher. The fuse would protect battery in case the circuit were damaged.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives V*I wattage at 1A: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside. Also take into account if circuit lives in an unventilated enclosure, or even a controls cabinet, these are above ambient.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd feel better with 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. Actual current when blowing higher. The use of the fuse would be to protect battery from shorting into a damaged circuit.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives V*I wattage at 1A: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside. Also take into account if circuit lives in an unventilated enclosure, or even a controls cabinet, these are above ambient.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd feel better with 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.
#6: Post edited by user avatar Pete W‭ · 2025-11-21T02:23:01Z (10 months ago)
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. Actual current when blowing higher. The fuse would protect battery in case the circuit were damaged.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives V*I wattage at 1A: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside. Also take into account if circuit lives in an unventilated enclosure, or even a controls cabinet, these are above ambient.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd think about 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. Actual current when blowing higher. The fuse would protect battery in case the circuit were damaged.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives V*I wattage at 1A: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside. Also take into account if circuit lives in an unventilated enclosure, or even a controls cabinet, these are above ambient.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd feel better with 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.
#5: Post edited by user avatar Pete W‭ · 2025-11-21T02:21:54Z (10 months ago)
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. The fuse would protect battery in case the circuit were damaged.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives V*I wattage at 1A: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside. Also take into account if circuit lives in an unventilated enclosure, or even a controls cabinet, these are above ambient.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd think about 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. Actual current when blowing higher. The fuse would protect battery in case the circuit were damaged.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives V*I wattage at 1A: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside. Also take into account if circuit lives in an unventilated enclosure, or even a controls cabinet, these are above ambient.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd think about 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.
#4: Post edited by user avatar Pete W‭ · 2025-11-21T01:41:41Z (10 months ago)
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. The fuse would protect battery in case the circuit were damaged.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives V*I wattage at 1A: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd think about 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. The fuse would protect battery in case the circuit were damaged.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives V*I wattage at 1A: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside. Also take into account if circuit lives in an unventilated enclosure, or even a controls cabinet, these are above ambient.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd think about 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.
#3: Post edited by user avatar Pete W‭ · 2025-11-21T01:40:08Z (10 months ago)
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. The fuse would protect battery in case the circuit were damaged.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives resulting wattage: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd think about 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. The fuse would protect battery in case the circuit were damaged.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives V*I wattage at 1A: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd think about 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.
#2: Post edited by user avatar Pete W‭ · 2025-11-21T01:35:27Z (10 months ago)
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. The fuse would protect battery in case the circuit were damaged.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives resulting wattage: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside.
  • TVS: 5.0SMJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd think about 5.0SMJ58A or 5.0SMJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.
  • Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. The fuse would protect battery in case the circuit were damaged.
  • Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives resulting wattage: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside.
  • TVS: 5.0SMDJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd think about 5.0SMDJ58A or 5.0SMDJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.
  • MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.
  • Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.
#1: Initial revision by user avatar Pete W‭ · 2025-11-21T01:33:17Z (10 months ago) 
Inrush, overcurrent, fuse, etc: That hot-swap IC has both current limit (ie for diode and fuse) and MOSFET-power limit, so you shouldn't blow a normal 3A fuse in the time it takes those limits to activate. The fuse would protect battery in case the circuit were damaged.

Series Diode: V1PM15 -- could work with careful thermal design. Could be a size larger. 150V is a good choice. Datasheet I-V-temperature graph gives resulting wattage: 0.5W-1W (with 0.5 being hot), and that'll be similar in a larger package. The 130C/W called out for the "minimal footprint" (with the DO219AD) can be improved with extra copper at the pad, and 4 layer stack with plane in the second layer. But that means effectively enlarging the floorspace it takes up, so then a bigger diode package may be a safer bet without any downside.

TVS: 5.0SMJ54A -- Strictly speaking, supply_max=65V exceeds Vrwm=54V. Looking at Vbr(1mA)=60V-66V (at 25C and rising with temperature), it would conduct, and for specimens on the low end of the Vbr, might settle into a livable equilibrium after self heating. Is that too aggressive for an industrial application? I'd think about 5.0SMJ58A or 5.0SMJ60A; Noting that Vcl then gets close to the 100V limit of both the LM5069 and the mosfet.

MOSFET: SI4058DY-T1- -- Should be fine. If you want more margin nothing wrong with using a 150V model. It's exposed to the Vcl of the TVS, just like the LM5069, but at least it would be one less thing that can get close to its limits. Looks plenty fast and easy to drive.

Last but not least, as it's a battery system - is there some kind of motor/generator that charges the battery or runs off of it? Abrupt stoppage of those, if not clamped, can potentially make big surges.