7
FN9062.2
April 13, 2004
Functional Pin Description (SOIC pinout)
3V3 (Pin 5)
Connect this pin to the ATX 3.3V output. This pin provides
the output current for the 1V2VID pin, and is monitored for
power quality.
5VSB (Pin 16)
Provide a very well de-coupled 5V bias supply for the IC to
this pin by connecting it to the ATX 5V
SB
output. This pin
provides all the chip’s bias as well as the base current for Q2
(see typical application diagram). The voltage at this pin is
monitored for power-on reset (POR) purposes.
GND (Pin 8)
Signal ground for the IC. All voltage levels are measured
with respect to this pin.
S3 and S5 (Pins 6 and 7)
These pins switch the IC’s operating state from active (S0,
S1/S2) to S3 and S4/S5 sleep states. These are digital
inputs featuring internal 50k (typical) resistor pull-ups to
5VSB. Internal circuitry de-glitches these pins for
disturbances lasting as long as 2s (typically). Additional
circuitry blocks any illegal state transitions (such as S3 to
S4/S5 or vice versa). Respectively, connect S3
and S5 to the
computer system’s SLP_S3
and SLP_S5 signals.
FAULT (Pin 9)
In case of an undervoltage on any of the controlled outputs,
on any of the monitored ATX voltages, or in case of an
overtemperature event, this pin is used to report the fault
condition by being pulled to 5VSB. Connect a 1k resistor
from this pin to GND.
SS (Pin 13)
Connect this pin to a small ceramic capacitor (no less than
5nF; 0.1F recommended). The internal soft-start (SS)
current source along with the external capacitor creates a
voltage ramp used to control the ramp-up of the output
voltages. Pulling this pin low with an open-drain device shuts
down all the outputs as well as force the FAULT pin low. The
C
SS
capacitor is also used to provide a controlled voltage
slew rate during active-to-sleep transitions on the
3.3V
DUAL
/3.3V
SB
output.
3V3DL (Pin 3)
Connect this pin to the 3.3V dual/stand-by output (V
OUT3
).
In sleep states, the voltage at this pin is regulated to 3.3V; in
active states, ATX 3.3V output is delivered to this node
through a fully-on N-MOS transistor. During all operating
states, this pin is monitored for undervoltage events. This pin
provides all the output current delivered by the 1V5SB pin.
3V3DLSB (Pin 2)
Connect this pin to the base of a suitable NPN transistor. In
sleep state, this transistor is used to regulate the voltage at
the 3V3DL pin to 3.3V.
DLA (Pin 10)
This pin is an open-collector output. Connect a 1k resistor
from this pin to the ATX 12V output. This resistor is used to
pull the gates of suitable N-MOSFETs to 12V, which in active
state, switch in the ATX 3.3V and 5V outputs into the
3.3V
DUAL
/3.3V
SB
and 5V
DUAL
outputs, respectively.
5VDL (Pin 12)
Connect this pin to the 5V
DUAL
output (V
OUT4
). In either
operating state (when on), the voltage at this pin is provided
through a fully-on MOS transistor. This pin is also monitored
for undervoltage events.
5VDLSB (Pin 11)
Connect this pin to the gate of a suitable P-MOSFET or
bipolar PNP. ISL6504: In S3 sleep state, this transistor is
switched on, connecting the ATX 5V
SB
output to the 5V
DUAL
regulator output. ISL6504A: In S3 and S4/S5 sleep state,
this transistor is switched on, connecting the ATX 5V
SB
output to the 5V
DUAL
regulator output.
1V5SB (Pin 1)
This pin is the output of the internal 1.5V regulator (V
OUT1
).
This internal regulator operates for as long as 5V
SB
is
applied to the IC and draws its output current from the
3V3DL pin. This pin is monitored for undervoltage events.
1V2VID (Pin 4)
This pin is the output of the internal 1.2V voltage
identification (VID) regulator (V
OUT2
). This internal regulator
operates only in active states (S0, S1/S2) and is shut off
during any sleep state. This regulator draws its output
current from the 3V3 pin. This pin is monitored for
undervoltage events.
VID_PG (Pin 14)
This pin is the open collector output of the 1V2VID power
good comparator. Connect a 10kpull-up resistor from this
pin to the 1V2VID output. As long as the 1V2VID output is
below its UV threshold, this pin is pulled low.
VID_CT (Pin 15)
Connect a small capacitor from this pin to ground. The
capacitor is used to delay the VID_PG reporting the 1V2VID
has reached power good limits.
Description
Operation
The ISL6504/A controls 4 output voltages (Refer to Figures
1, 2, and 3). It is designed for microprocessor computer
applications with 3.3V, 5V, 5V
SB
, and 12V bias input from an
ATX power supply. The IC is composed of three linear
controllers/regulators supplying the computer system’s
1.5V
SB
(V
OUT1
), 3.3V
SB
and PCI slots’ 3.3V
AUX
power
(V
OUT3
), the 1.2V VID circuitry power (V
OUT2
), a dual
switch controller supplying the 5V
DUAL
voltage (V
OUT4
), as
ISL6504, ISL6504A
