RT9641A Datasheet, PDF (1/14 Pages) Richtek Technology Corporation – TRIPLE LINEAR REGULATOR CONTROLLER SUPPORT

RT9641A/B
Triple Linear Regulator Controller Support
ACPI Control Interface
General Description
The RT9641A/B, paired with either the RT9230 or
RT9231 simplifies the implementation of ACPI-
compliant designs in microprocessor and computer
applications. The IC integrates two linear controllers
and a low-current pass transistor, as well as the
monitoring and control functions into a 16-pin SOIC
package. One linear controller generates the
3.3V_DUAL voltage plane from an ATX power supply's
5VSB output during sleep states (S3,S4/S5),
powering the PCI slots through an external pass
transistor, as instructed by the status of the 3.3V_DUAL
enable pin. An additional pass transistor is used to
switch in the ATX 3.3V output for PCI operation
during S0 and S1 (active) operating states. The
second linear controller supplies the computer
system's 2.5V/3.3V memory power through an
external pass transistor in active states. During S3
state, an integrated pass transistor supplies the
2.5V/3.3V sleep-state power. A third controller
powers up a 5V_DUAL plane by switching in the ATX
5V output in active states, or the ATX 5VSB in sleep
states.
The RT9641A/B's operating mode (active-state
outputs or sleep-state outputs) is selectable through
two control pins: S3 and S5. Further control of the
logic governing activation of different power modes is
offered through two enabling pins: EN3VDL and
EN5VDL. In active states, the 3.3V_DUAL linear
regulator uses an external N-channel pass MOSFET
to connect the output (V_OUT1) directly to the 3.3V
input supplied by an ATX (or equivalent) power
supply, while incurring minimal losses. In sleep state,
the 3.3V_DUAL output is supplied from the ATX 5VSB
through a NPN transistor, also external to the
controller. Active state power delivery for the
2.5V/3.3V or 2.6V/3.43V V_MEM output is done
through an external NPN or a NMOS transistor. In
sleep states, conduction on this output is transferred
to an internal pass transistor. The 5V_DUAL output is
powered through two external MOS transistors. In
sleep states, a PMOS (or PNP) transistor conducts
the current from the ATX 5VSB output, while in active
states, current flow is transferred to a NMOS
transistor connected to the ATX 5V output. Similar to
the 3.3V_DUAL output, the operation of the 5V_DUAL
output is dictated not only by the status of the S3 and
S5 pins, but that of the EN5VDL pin as well.
Features
z Provides 3 ACPI-Controlled Voltages
− 5V Active/Sleep(5V_DUAL)
z 3.3V Active/Sleep(3.3V_DUAL)
− 2.5V/3.3V Active/Sleep(V_MEM) with RT9641A
− 2.6V/3.43V Active and 2.5V/3.3V Sleep(V_MEM)
with RT9641B
z Simple Control Design
− No Compensation Required
z Excellent Output Voltage Accuracy
− 3.3V_DUALOutput： ±2.0%； Sleep States Only
− 2.5V/3.3V (2.6V/3.43V) Output： ±2.0%；
Both Operational States
z Fixed Output Voltages Require No Precision
External Resistors
z Small Size
− Small External Component Count
z Selectable 2.5V/3.3V (2.6/3.43) V_MEM Output
Voltage via FAULT/MSEL Pin
− 2.5V/2.6V for RDRAM Memory
− 3.3V/3.43V for SDRAM Memory
z Under-voltage Monitoring of All Outputs with
Centralized FAULT Reporting
z Adjustable Soft-start Function Eliminates 5VSB
Perturbations
DS9641A/B-03 March 2002
www.richtek-ic.com.tw
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