4
FN6457.0
September 25, 2007
Pin Descriptions
PIN
NAME
FUNCTION
9, 28    FORCE_ON
A,
FORCE_ON
B
Asserting a FORCE_ON
input low will turn on the MAIN and AUX supplies to the respective slot in a forced mode
over riding the ON input and the UV, OC and short circuit protections on those outputs. UVLO protection for the
VSTBY input is not affected by the FORCE_ON
pins. Asserting FORCE_ON
will cause the PWRGD
and FAULT
outputs to enter their open-drain state. This input is internally pulled high to the VAUX rail. Functionality is disabled
when PRSNT
is high.
44, 43    ONA, ONB   Enable input for MAIN outputs use to enable or disable MAIN voltage supply (12V and 3.3V) outputs. Taking ONX
low after a fault resets the respective slots Main Output Fault Latch. Functionality is disabled when PRSNT
is high.
45, 42  AUXENA, AUXENB 3.3VAUX Enable Input, enables the respective VAUX output. Pulling AUXENX low after a fault resets the
associated slots VAUX fault latch. Functionality is disabled when PRSNT
is high.
5, 32   12VINA,12VINB  Connect to 12VMAIN supply and high side of sense resistor. This is one of two pins for Kelvin connection to
measure the 50mV CR Vth. An undervoltage lockout prevents the IC main supply function until 12VIN >10V. The
current regulation threshold is set by connecting a sense resistor between this pin and 12VSENSE. When the
current-limit threshold of IR = 50mV is reached, the 12VGATE pin is modulated to maintain a constant 50mV
voltage across the sense resistor and thereby a constant current is passed into the load. If the 50mV threshold is
maintained for CR duration, the circuit breaker is tripped and both GATE pins for the affected slot turn off the
switch FETs and thus turn off the supplies to the slot.
8, 29    12VSENSEA,
12VSENSEB
12V current sense low side input. This is the second of two pins for Kelvin connection to the R
SENSE
to measure
the 50mV CR Vth. The CR limits are set by connecting a sense resistor between each of these pins and
associated 12VIN pin.
10, 27    12VOUTA,
12VOUTB
12V output voltage monitor for UV condition. This is the voltage input downstream of the MOSFET that is delivered
to the add-in card load.
12, 25   3VINA, 3VINB  Connect to 3VMAIN supply and high side of sense resistor. This provides one of two pins for Kelvin connection to
measure the 50mV CR Vth. Undervoltage lockout (UVLO) prevents turn-on until 3VIN >2.75V. The current
regulation threshold is set by connecting a sense resistor between this pin and 3VSENSE. When the current-limit
threshold of IR = 50mV is reached, the 3VGATE pin is modulated to maintain a constant 50mV voltage across the
sense resistor and thereby a constant current is passed into the load. If the 50mV threshold is maintained for the
CR duration, the circuit breaker is tripped and both FETs for the affected slot are turned-off.
13, 24    3VSENSEA,
3VSENSEB
3.3V current sense low side input. This provides the second of two pins for Kelvin connection for measuring the
50mV CR Vth. The CR limits are set by connecting a sense resistor between each of these pins and associated
3VINX pin.
16, 21    3VOUTA,
3VOUTB
3.3V output voltage monitor for UV condition. This is the voltage downstream of the MOSFET that is delivered to
the add-in card load.
1, 36   FAULT
A, FAULT
B An open drain output which is pulled low whenever the CR duration has expired due to an OC fault condition on
any of the MAIN or the AUX supplies or in the event of an IC over-temperature condition. If fault latch is invoked
by a MAIN (+12V, +3.3V) supply fault, then it is reset by pulling the faulted slots ON pin low. if fault was asserted
because of an OC fault condition on the slots AUX output then pulling the AUXEN input low will reset the latch.
Both enabling inputs must be pulled low to clear a fault condition on both the MAIN and VAUX outputs of the same
slot. Internal over-temperature limit is ~+140癈 with a +20癈 hysteresis.
15, 22    VAUXA, VAUXB  3.3VAUX output to the PCI-E slot: This output connects to the VAUX pin of the PCI-E connector through an internal
0.3?FET. This output is current regulated to ~1A.
11, 26
VSTBYA
VSTBYB
3.3V bias input for the IC, and internal VAUX switches. V
VSTBY
must always be present for proper IC bias, either
from a dedicated 3.3V or 3VMAIN if AUX supply not implemented.
41
L/R
Latch-off or Retry bar input. Tying this input low invokes a periodic retry to turn-on after current regulation timer
has expired on both slots. Leaving this pin open provides a latch-off operational mode after CR period has expired.
In this mode turn-on is initiated by cycling the appropriate EN input(s). This pin is internally pulled up to VSTBY.
40, 39  PRSNT
A, PRSNT
B The card presence detection input disables the operation of the FORCE_ON
, ON and AUXEN inputs if not pulled
to GND. If after turn-on, the PRSNT
input goes high then all associated outputs (MAIN and AUX) are turned off
immediately.
6, 31    PWRGD
A,
PWRGD
B
A POWER GOOD NOT signal that is asserted low while all output voltages are compliant.
4, 38   GPI_A0, GPI_B0   ~5ms debounced user attention input, driven by either a mechanical switch or digital signal form higher level
controller.
48, 47  GPO_A0, GPO_B0 User attention output, that can be used to drive LEDs, alarms or other attention getting devices. Open drain with
90mA pull-down capability.
ISL6113, ISL6114