Rainbow Electronics MAX5958 - Manual (Page 11)

MAX5957/MAX5958
Triple PCI Express, Hot-Plug Controllers
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Pin Description
PIN NAME FUNCTION
1 12SB-
Slot B 12V Negative Current-Sense Input. Connect 12SB- to the negative side of the current-sense
resistor using the Kelvin-sensing technique to ensure accurate current sensing.
2 12SB+
Slot B 12V Positive Current-Sense Input. Connect the positive terminal of the current-sense resistor
to 12SB+ using the Kelvin-sensing technique to ensure accurate current sensing.
3 AUXONB Slot B 3.3V Auxiliary Output Enable. A logic-high at AUXONB turns on the slot B auxiliary output.
4 ONB
Slot B 12V and 3.3V Main Outputs Enable. A logic-high at ONB turns on the 12V and 3.3V main
outputs of slot B (see Table 2).
5 INPUT1 Digital Logic Gate Input 1
6 OUTPUT1 Digital Output One. 4ms debounced digital output of INPUT1.
7 INPUT2 Digital Logic Gate Input 2
8 OUTPUT2 Digital Output 2. 4ms debounced digital output of INPUT2.
9, 27 GND Ground
10 FONC
Slot C Forced-On Input. FONC has a 50k Ω internal pullup to 3.3VAUXIN. A logic-low on FONC turns
on all slot C outputs as long as the power inputs are within their operating range, regardless of the
status of the other input signals. Leave FONC unconnected for normal operation.
11 PRES-DETC
Slot C Present-Detect Input. PRES-DETC accepts inputs from PRSNT-# on a PCIe connector. PRES-
DETC has an internal 50k
Ω pullup to 3.3VAUXIN. When PRES-DETC is low, the outputs follow the
command from ONC and AUXONC after a 4ms debounced time. When PRES-DETC goes from low
to high, all outputs of the respective slot shut down with no delay.
12 ONC
Slot C 12V and 3.3V Main Outputs Enable. A logic-high at ONC turns on the 12V and 3.3V main
outputs of slot C (see Table 2).
13 AUXONC Slot C 3.3V Auxiliary Output Enable. A logic-high at AUXONC turns on the slot C auxiliary output.
14 12SC+
Slot C 12V Positive Current-Sense Input. Connect the positive terminal of the current-sense resistor
to 12SC+ using the Kelvin-sensing technique to ensure accurate current sensing.
15 12SC-
Slot C 12V Negative Current-Sense Input. Connect 12SC- to the negative side of the current-sense
resistor using the Kelvin-sensing technique to ensure accurate current sensing.
16 12GC
Slot C 12V Gate-Drive Output. Connect 12GC to the gate of slot C’s 12V MOSFET. At power-up,
12GC is raised to the internal charge-pump voltage level by a constant current.
17 3.3SC+
Slot C 3.3V Positive Current-Sense Input. Connect the positive side of the current-sense resistor to
3.3SC+ using the Kelvin-sensing technique to ensure accurate current sensing.
18 3.3SC-
Slot C 3.3V Negative Current-Sense Input. Connect to the negative side of the sense resistor using
the Kelvin-sensing technique to ensure accurate current sensing.
19 3.3GC
Slot C 3.3V Gate-Drive Output. Connect 3.3GC to the gate of slot C’s 3.3V MOSFET. At power-up,
3.3GC is charged to 5.5V above the 3.3V supply by a constant current derived from V
12VIN . V 3.3GC‘s
rise time is determined by the external gate capacitance.
20 FAULTC
Open-Drain Fault Output Signal. FAULTC latches active low whenever slot C outputs are shut down
due to a fault. A fault is either of:
• An overcurrent condition lasting longer than the overcurrent timeout.
• A device over the temperature condition.
If the fault is detected in the main outputs, FAULTC must be reset by toggling the ONC input. If the
fault is in the auxiliary output, FAULTC must be reset by toggling both ONC and AUXONC. For the
autorestart version, FAULTC is reset when the part initiates the next power-on cycle.
21 PWRGDC
Open-Drain Power-Good Output. PWRGDC goes low 160ms after all outputs of slot C reach their
final value and the power MOSFETs are fully enhanced.