A Five-Channel (Three +V and Two -V) Hot-Swap Reference Design

This five-channel circuit provides hot-swap functions for three positive-voltage circuits and for two negative-voltage circuits, though it employs only a single MAX5927A four-channel hot-swap controller. The Figure 1 circuit meets the following load and power-sequencing requirements:

• Ch1 = +3.3V at 2A (circuit breaker at ≥ 3A)
• Ch2 = +5V at 1.6A (circuit breaker at ≥ 2.4A)
• Ch3 = +12V at 2A (circuit breaker at ≥ 3A)
• Ch4 = -12V at 150mA (no circuit-breaker action)
• Ch5 = -5V at 50mA (no circuit-breaker action)
• Startup timing is such that channels 2 (+5V) and 3 (+12V) begin to turn on as soon as active-low CARD_PRESENT goes low. STAT2 and STAT3 go active-high 10.8ms after active-low CARD_PRESENT goes low.
• Channel 1 (+3.3V) turn-on is delayed by 11.8ms from channels 2 and 3. STAT1 goes high 10.8ms after channel 1 begins to turn on.
• Turn-on of channels 4 (-12V) and 5 (-5V) is delayed by 27.8ms from channels 2 and 3. STAT4 goes high 10.8ms after channels 4 and 5 begin to turn on.
• Latching fault management. If any of channels 1 through 3 experiences a fault, all channels will