6
FN4882.5
July 21, 2005
Functional Pin Description
3V3 (Pin 7)
Connect this pin to the ATX 3.3V output. This pin provides
the output current for the 2V5CLK pin, and is monitored for
power quality.
5VSB (Pin 1)
Provide a very well de-coupled 5V bias supply for the IC to
this pin by connecting it to the ATX 5VSB output. This pin
provides the output current for the VSEN1 and VSEN2 pins,
as well as the base current for Q2. The voltage at this pin is
monitored for power-on reset (POR) purposes.
5V (Pin 18)
Connect this pin to the ATX 5V output. This pin provides the
base bias current for Q1, and is monitored for power quality.
12V (Pin 17)
Connect this pin to the ATX 12V output. This pin provides the
gate bias voltage for Q3, Q5 and Q6, and is monitored for
power quality.
GND (Pin 11)
Signal ground for the IC. All voltage levels are measured
with respect to this pin.
S3 and S5 (Pins 9 and 10)
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.
EN5VDL (Pin 8)
This pin enables or disables sleep state support on the
5V
DUAL
output in response to S3 and S4/S5 requests. This
is a digital input pin whose status can only be changed
during active state operation or during chip shutdown (SS
pin grounded by external open-drain device or chip bias
below POR level). The input information is latched-in when
entering a sleep state, as well as following 5VSB POR
release or exit from shutdown. EN5VDL is internally pulled
high through a 40A current source.
FAULT/MSEL (Pin 12)
This is a multiplexed function pin allowing the setting of the
memory output voltage to either 2.5V or 3.3V (for RDRAM or
SDRAM memory systems). An internal 40A current source
creates a voltage across an external resistor - this voltage
level is compared to an internal 200mV reference and the
memory regulator output voltage is set.
In case of an undervoltage on any of the controlled outputs,
on any of the monitored ATX supplies, or in case of an
overtemperature event, this pin is used to report the fault
condition by being pulled to 5VSB.
SS (Pin 16)
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
and 2.5V
MEM
/3.3V
MEM
outputs.
VSEN2 (Pin 20)
Connect this pin to the memory output (V
OUT2
). In sleep
states, this pin is regulated to 2.5V through an internal pass
transistor capable of delivering 300mA (typically). The
active-state voltage at this pin is regulated through an
external NPN transistor connected at the DRV2 pin. During
all operating states, the voltage at this pin is monitored for
under-voltage events.
DRV2 (Pin 19)
Connect this pin to the base of a suitable NPN transistor.
This pass transistor regulates the 2.5V output from the ATX
3.3V during active states operation.
3V3DL (Pin 5)
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 under-voltage events.
3V3DLSB (Pin 4)
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 13)
Connect this pin to the gates of suitable N-MOSFETs, which
in active state, switch in the ATX 3.3V and 5V outputs into
the 3.3V
MEM
, 3.3V
DUAL
/3.3V
SB
and 5V
DUAL
outputs,
respectively.
5VDL (Pin 15)
Connect this pin to the 5V
DUAL
output (V
OUT5
). In either
operating state, the voltage at this pin is provided through a
fully on MOS transistor. This pin is also monitored for under-
voltage events.
5VDLSB (Pin 14)
Connect this pin to the gate of a suitable P-MOSFET or
bipolar PNP. In sleep state, this transistor is switched on,
connecting the ATX 5VSB output to the 5V
DUAL
regulator
output.
HIP6503
