RICHTEK RT9641AC32

RT9641A/B
Triple Linear Regulator Controller Support
ACPI Control Interface
General Description
The RT9641A/B, paired with either the RT9230 or
powered through two external MOS transistors. In
RT9231 simplifies the implementation of ACPI-
sleep states, a PMOS (or PNP) transistor conducts
compliant designs in microprocessor and computer
the current from the ATX 5VSB output, while in active
applications. The IC integrates two linear controllers
states, current flow is transferred to a NMOS
and a low-current pass transistor, as well as the
transistor connected to the ATX 5V output. Similar to
monitoring and control functions into a 16-pin SOIC
the 3.3VDUAL output, the operation of the 5VDUAL
output is dictated not only by the status of the S3 and
package.
One
linear
controller
generates
the
3.3VDUAL 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 3.3VDUAL
S5 pins, but that of the EN5VDL pin as well.
Features
z
− 5V Active/Sleep(5VDUAL)
enable pin. An additional pass transistor is used to
switch in the ATX 3.3V output for PCI operation
Provides 3 ACPI-Controlled Voltages
z
3.3V Active/Sleep(3.3VDUAL)
during S0 and S1 (active) operating states. The
− 2.5V/3.3V Active/Sleep(VMEM) with RT9641A
second linear controller supplies the computer
− 2.6V/3.43V Active and 2.5V/3.3V Sleep(VMEM)
with RT9641B
system's 2.5V/3.3V memory power through an
external pass transistor in active states. During S3
z
− No Compensation Required
state, an integrated pass transistor supplies the
2.5V/3.3V sleep-state power. A third controller
z
− 2.5V/3.3V (2.6V/3.43V) Output:
: ±2.0%;
;
Both Operational States
5V output in active states, or the ATX 5VSB in sleep
states.
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
z
z
supply, while incurring minimal losses. In sleep state,
the 3.3VDUAL output is supplied from the ATX 5VSB
through a NPN transistor, also external to the
Small Size
− Small External Component Count
z
Selectable 2.5V/3.3V (2.6/3.43) VMEM Output
Voltage via FAULT/MSEL Pin
− 2.5V/2.6V for RDRAM Memory
regulator uses an external N-channel pass MOSFET
input supplied by an ATX (or equivalent) power
Fixed Output Voltages Require No Precision
External Resistors
EN5VDL. In active states, the 3.3VDUAL linear
to connect the output (VOUT1) directly to the 3.3V
Excellent Output Voltage Accuracy
− 3.3VDUALOutput:
: ±2.0%;
; Sleep States Only
powers up a 5VDUAL plane by switching in the ATX
The
Simple Control Design
− 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
controller. Active state power delivery for the
2.5V/3.3V or 2.6V/3.43V VMEM 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 5VDUAL output is
DS9641A/B-03 March 2002
www.richtek-ic.com.tw
1
RT9641A/B
Ordering Information
Pin Configurations
RT9641A/B… …
Part Number
Package type
S2 : SOP-16
Pin Configurations
TOP VIEW
RT9641ACS2
(Plastic SOP-16)
Operating temperature range
C: Commercial standard
VMEM voltage
RT9641BCS2
A : 2.5V/3.3V
(Plastic SOP-16)
B : 2.6V/3.43V
5VSB
EN3VDL
1
16
VSEN2
2
15
3V3DLSB
3V3DL
3
14
DRV2
12V
4
13
SS
EN5VDL
S3
5
12
6
11
S5
GND
7
8
5VDL
5VDLSB
10 DLA
9 FAULT/MSEL
Function Block Diagram
12V
3V3DLSB
3V3DL
5VSB
TO 12V
EA4 _
DLA
+
12V BIAS
12V MONITOR
10.5V/9.5V
5VSB POR
5VDLSB
UV
DETECTOR
MONITOR AND CONTROL
+
TEMPERATURE
MONITOR
(TMON)
+
+
MEM VOLTAGE
SELECT COMP
_
_ 1.265V
DRV2
UA COMPARTOR
5VDL
VSEN2
_
+
+
_ 3.75V
5µA
SS
www.richtek-ic.com.tw
2
+
EA2
TO
UV DEECTOR
_
0.2V
_
40µA
EN3VDL
S3
S5 EN5VDL
GND
DS9641A/B-03 March 2002
RT9641A/B
Absolute Maximum Ratings
z
Supply Voltage (V5VSB)
+7.0V
z
12V
GND−0.3V to +14.5V
z
DLA, DRV2
GND−0.3V to V12V+0.3V
z
All Other Pins
GND−0.3V to 5VSB+0.3V
z
Package Thermal Resistance
SOP-16, θJA
100°C/W
z
Maximum Junction Temperature
150°C
z
Maximum Storage Temperature Range
-65°C to 150°C
z
Maximum Lead Temperature (Soldering, 10 sec.)
300°C
Recommended Operating Conditions
+5V ± 5%
z
Supply Voltage (V5VSB)
z
Secondary Bias Voltage (V12V)
+12V ± 10%
z
Digital Inputs (VS3, VS5, VEN3VDL, VEN5VDL)
0 to + 5.5V
z
Junction Temperature Range
0°C to 125°C
z
Ambient Temperature Range
0°C to 70°C
CAUTION:
Stresses beyond the ratings specified in “Absolute Maximum Ratings” may cause permanent damage to the
device. This is a stress only rating and operation of the device at these or any other conditions above those
indicated in the operational sections of this specification is not implied.
Electrical Characteristics
(VCC (12VIN) = 12V, GND = 0V, TA = 25°C, unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Units
--
7
20
mA
--
2
10
mA
Rising 5VSB POR Threshold
--
2.5
--
V
Rising 12V Threshold
--
10.5
11
V
--
6.5
--
µA
--
0.8
VCC Supply Current
Operating Supply Current
I5VSB
Shutdown Supply Current
I5VSB(OFF)
VSS = 0V, S3 = 0, S5 =0
Power-on Reset, Soft-start, and 12V Monitor
Soft-start Current
Shutdown Soft-start Voltage
DS9641A/B-03 March 2002
ISS
-V
To be continued
www.richtek-ic.com.tw
3
RT9641A/B
Parameter
Symbol
Test Conditions
Min
Typ
Max
Units
--
--
2.0
%
2.5V/3.3V (2.6V/3.43V) Linear Regulator (VOUT2)
Regulation
VSEN2 Nominal Voltage Level
VVSEN
RSEL = 1KΩ
--
2.5/2.
--
V
VSEN2 Nominal Voltage Level
VVSEN2
RSEL = 1KΩ
--
3.3/3.
--
V
VSEN2 Under-voltage Falling Threshold
--
68
--
%
VSEN2 Under-voltage Hysteresis
--
7
--
%
VSEN2 Output Current
IVSEN2
5VSB = 5V
200
300
--
mA
DRV2 Output Drive Current
IDRV2
5VSB = 5V, RSEL = 1KΩ
20
30
--
mA
RSEL = 10KΩ
--
200
--
Ω
--
--
2.0
%
--
3.3
--
V
3V3DL Under-voltage Falling Threshold
--
2.24
--
V
3V3DL Under-voltage Hysteresis
--
230
--
mV
5.0
10
--
mA
--
90
--
Ω
5VDL Under-voltage Falling Threshold
--
3.40
--
V
5VDL Under-voltage Hysteresis
--
350
--
mV
-40
--
--
mA
--
10
--
µS
50
--
mS
DRV2 Output Impedance
3.3V Dual Linear Regulator (VOUT1)
Sleep-mode Regulation
3V3DL Nominal Voltage Level
3V3DLSB Output Drive Current
V3V3DL
I3V3DLS
5VSB = 5V
DLA Output Impedance
5V Dual Switch Controller (VOUT3)
5VDLSB Output Drive Current
I5VDLSB
5VDLSB = 4V
Timing Intervals
Active to Sleep, Input to Switching Delay
Sleep to Active, Input to Switching Delay
Td1
Td2
CSS = 0.1µF
(1)
(1)
--
Control I/O (S3, S5, EN3VDL, EN5VDL, FAULT)
High Level Threshold
2.0
--
--
V
Low Level Threshold
--
--
0.8
V
S3, S5 Internal Pull-up Impedance to 5VSB
--
50
--
KΩ
--
100
--
Ω
--
145
--
°C
--
155
--
°C
FAULT Output Impedance
FAULT = high
Temperature Monitor
Fault-level Threshold
Shutdown-level Threshold
Note:
(1)
= 50mS with 0.1µF Soft-start capacitor. The delay time is adjustable with td2 = 500xCSS (mS).
www.richtek-ic.com.tw
4
TDS
DS9641A/B-03 March 2002
RT9641A/B
Simplified Power System Diagram
5VIN
12VIN
5VSB
3.3VIN
Linear
Controller
Q2
3.3VDUAL
FAULT
Q3
Linear
Controller
Q1
VMEM
RT9641A/B
Control
Logic
Q4
Q5
5VDUAL
SHUTDOWN
S3
S5
EN5VDL
EN3VDL
DS9641A/B-03 March 2002
www.richtek-ic.com.tw
5
RT9641A/B
Functional Pin Description
5VSB (Pin 1)
FAULT/MSEL (Pin 9)
Provide a 5V bias supply for the IC to this pin by
This is a multiplexed function pin allowing the setting
connecting it to the ATX 5VSB output. This pin also
of the memory output voltage to either 2.5V(2.6V) or
provides the base bias current for all the external
3.3V(3.43V)
NPN transistors controlled by the IC. The voltage at
systems). The memory voltage setting is latched-in
this
when SS pin voltage goes up to 0.8V (typically 5mS
pin monitored for
power-on reset (POR)
purposes.
EN3VDL and EN5VDL (Pin 2 and 5)
These pins control the logic governing the output
(for
RDRAM
or
SDRAM
memory
after POR). In case of an under-voltage on any of the
outputs or an over temperature event, this pin is used
to report the fault condition by being pulled to 5VSB.
behavior in response to S3 and S4/S5 requests.
DLA (Pin 10)
These are digital inputs whose status can only be
Connect this pin to the gates of suitable N-MOSFETs,
changed during active states operation or during chip
which in active states, are used to switch in the ATX
shutdown (SS pin grounded by external open-drain
3.3V and 5V outputs into the 3.3VDUAL and 5VDUAL
device). The input information is latched-in when
outputs, respectively.
entering a sleep state, as well as following 5VSB
POR release or exit from shutdown.
5VDLSB (Pin 11)
Connect this pin to the gate of a suitable P-MOSFET
3V3DLSB (Pin 3)
or bipolar PNP. In sleep states, this transistor is
Connect this pin to the base of a suitable NPN
switched on, connecting the ATX 5VSB output to the
transistor. In sleep states, this transistor is used to
5VDUAL regulator output. When PNP is used, it is
regulate the voltage at 3V3DL pin to 3.3V.
recommanded to use a 100Ω base resistor for base
3V3DL (Pin 4)
current limiting.
Connect this pin to the 3.3V dual output (VOUT1). In
5VDL (Pin 12)
sleep states, the voltage at this pin is regulated to
Connect this pin to the 5VDUAL output (VOUT3). In
3.3V; in active states, ATX 3.3V output is delivered to
either operating state, the voltage at this pin is
this node through a fully on N-MOS transistor. During
provided through a fully on MOS transistor. This pin
all operating states, this pin is monitored for under-
is also monitored for under-voltage events.
voltage events.
SS (Pin 13)
S3 and S5 (Pin 6 and 7)
Connect
These pins switch the IC’s operating state from active
recommended) from this pin to GND. The internal
(S0, S1) to S3 and S4/S5 sleep states. Connect S3
Soft-start (SS) current source along with the external
to SLP_S3 and S5 to SLP_S5. These are digital
capacitor creates a voltage ramp used to control the
inputs featuring internal 50kΩ (typical) resistor pull-up
ramp-up of the output voltages. Pulling this pin low
to 5VSB. Internal circuitry de-glitches the S3 pin for
with an open-drain device shuts down all the output
disturbances.
GND (Pin 8)
Signal ground for the IC. All voltage levels are
a
small
ceramic
capacitor
(0.1µF
as well as forces the FAULT pin low. The CSS
capacitor is also used to provide a controlled S4/S5
to active transition delay time.
measured with respect to this pin.
www.richtek-ic.com.tw
6
DS9641A/B-03 March 2002
RT9641A/B
12V (Pin 14)
VSEN2 (Pin 16)
Connect this pin to the ATX (or equivalent) 12V
Connect this pin to the memory output (VOUT2). In
output. This pin is used to monitor the status of the
sleep states, this pin is regulated to 2.5V(2.6V) or
power supply as well as provide bias for the NMOS-
3.3V(3.43V) (based on RSEL) through an internal
compatible output drivers. 12V presence at the chip
pass
in the absence of bias voltage, or severe 12V
(Typically). The active-state voltage at this pin is
brownout during active states (S0, S1) operation can
regulated through an external NPN or NMOS
lead
transistor connected at the DRV2 pin for both
to
chip
misbehavior.
RT9641A/B
refuses
entering active state before 12V power ready.
DRV2 (Pin 15)
For the 2.5V RDRAM systems, connect this pin to the
transistor
capable
of
delivering
300mA
2.5V(2.6V) and 3.3V(3.43V) setting. During all
operating states, the voltage at this pin is monitored
for under-voltage events.
base of a suitable NPN transistor. This pass
transistor regulates the 2.5V(2.6V) output from the
ATX 3.3V during active states operation. For 3.3V
SDRAM systems connect this pin to the gate of a
suitable N-MOS transistor or the base of a suitable
NPN transistor.
Description
Operation
Operational Truth Tables
The RT9641A/B controls 3 output voltages. It is
The EN3VDL and EN5VDL pins offer a host of choices
designed for microprocessor computer applications
in terms of the overall system architecture and
with 3.3V, 5V, 5VSB, and 12V outputs from an ATX
supported features. Tables 1~3 describe the truth
power supply. The IC is composed of two linear
combinations pertaining to each of the three outputs.
controllers supplying the PCI slots' 3.3VAUX power
(3.3VDUAL, VOUT1) and the 2.5V RDRAM or 3.3V
SDRAM memory power (2.5V/3.3V(2.6V/3.43V) VMEM,
VOUT2), and a dual switch controller supplying the
Table 1. 3.3VDUAL Output (VOUT1) Truth Table
EN3VDL S5 S3 3V3D
Comments
0
1
1
3.3V
S0, S1 States (Active)
0
1
0
3.3V
S3
0
0
1
Note
Maintains Previous State
0
0
0
3.3V
S4/S5
The RT9641A/B automatically initializes upon receipt
1
1
1
3.3V
S0, S1 States (Active)
of input power. The Power-On Reset (POR) function
1
1
0
3.3V
S3
continually monitors the 5VSB input supply voltage,
1
0
1
Note
Maintains Previous State
initiating soft-start operation after it exceeds its POR
1
0
0
0V
S4/S5
5VDUAL voltage (VOUT3). In addition, all the control and
monitoring functions necessary for complete ACPI
implementation are integrated into the RT9641A/B.
Initialization
threshold (in S4/S5 states). The 5VSB POR trip event
is also used to lock in the memory voltage setting
based on RSEL.
The RT9641A/B forces the operation mode to start
from S4/S5 states at POR releasing.
DS9641A/B-03 March 2002
Note: Combination not allowed.
As seen in Table 1, EN3VDL simply controls whether
the 3.3VDUAL plane remains powered up during S4/S5
sleep state.
www.richtek-ic.com.tw
7
RT9641A/B
Table 2. 5VDUAL Output (VOUT3) Truth Table
EN5VDL S5 S3 5VDL
state. Exceeding the maximum current rating of this
Comments
output in a sleep state can lead to output voltage
0
1
1
5V
S0, S1 States(Active)
drooping. If excessive, this droop can ultimately trip the
0
1
0
0V
S3
under-voltage detector and send a FAULT signal to the
0
0
1
Note
Maintains Previous State
0
0
0
0V
S4/S5
1
1
1
5V
S0, S1 States(Active)
the circuit is desired, this can be achieved by externally
1
1
0
5V
S3
pulling or latching the SS pin low. Pulling the SS pin
1
0
1
Note
Maintains Previous State
1
0
0
5V
S4/S5
computer system. However, a FAULT condition will
only set off the FAULT flag, and it will not shut off or
latch off any part of the circuit. If shutdown or latch off
low will also force the FAULT pin to go low.
Under-voltage sensing is disabled on all disabled
Note: Combination not allowed.
outputs and during soft-start ramp-up intervals.
Very similarly, Table 2 details the fact that EN5VDL
Another condition that could set off the FAULT flag is
status controls whether the 5VDUAL plane supports
chip over-temperature. If the RT9641A/B reaches an
sleeps states.
internal temperature of 145°C (typical), the FAULT flag
is set (FAULT/MSEL pulled high), but the chip
Table 3. 2.5V/3.3V(2.6V/3.43V) VMEM Output (VOUT2)
Truth Table
RSEL S5 S3
continues to operate until the temperature reaches
155°C (typical), when unconditional shutdown of all
2.5V/3.3V
Comments
outputs takes place. The thermal shutdown can be
released with a re-soft-start when the chip cools down.
1KΩ
1
1
2.5V/2.6V
S0, S1 States(Active)
1KΩ
1
0
2.5V
S3
1KΩ
0
1
Note
Maintains Previous State
1KΩ
0
0
0V
S4/S5
10KΩ
1
1
3.3V/3.43V
S0, S1 States(Active)
10KΩ
1
0
3.3V
S3
drain or open collector device capable of sinking a
10KΩ
0
1
Note
Maintains Previous State
minimum of 2mA. Pulling the SS pin low effectively
10KΩ
0
0
0V
S4/S5
shuts down all the pass elements. Upon release of the
Shutdown
computer system, or at any other time, the RT9641A/B
output is maintained in S3 (Suspend-To-RAM), but not
state.
The
specified shutdown level (typically 0.8V) with an open
cycle and resumes normal operation in accordance to
As seen in Table 3, 2.5V/3.3V(2.6V/3.43V) VMEM
S4/S5
can be shut down by pulling the SS pin below the
SS pin, the RT9641A/B undergoes a new soft-start
Note: Combination not allowed.
in
In case of a FAULT condition that might endanger the
dual-voltage
support
accommodates both SDRAM as well as RDRAM type
memories.
the ATX supply and control pins status.
Layout Considerations
The typical application employing a RT9641A/B is a
fairly straight-forward implementation. Similar to any
other linear regulators, attention has to be paid to a
Fault Protection
few potentially sensitive small signal components, such
All the outputs are monitored against under-voltage
as those connected to high-impedance nodes or those
events. A serve over-current caused by a failed load
supplying critical by-pass currents.
on any of the outputs, would, in turn, cause that
specific output to suddenly drop. If any of the output
voltages drop below 68% of their set value, such event
is reported by having the FAULT/MSEL pin pulled to
5V. Additionally, the 2.5V/3.3V(2.6V/3.43V) memory
regulator is internally current limited while in a sleep
www.richtek-ic.com.tw
8
DS9641A/B-03 March 2002
RT9641A/B
The power components (pass transistors) and the
controller IC should be placed first. The controller
capacitor placement, but having these capacitors close
to the load they serve is preferable.
should be placed in a central position on the
The only critical small signal component is the soft-
motherboard, closer to the memory load if possible.
start capacitor, CSS. Locate the component close to SS
Ensure the VSEN2 connection is properly sized to
pin of the control IC and connect to ground though a
carry 300mA without significant resistive losses. The
vias placed close to the capacitor’s ground pad.
pass transistors should be placed on pads capable of
Minimize any leakage current paths from SS node,
heatsinking, matching the device’s power dissipation.
since the internal current source is only 5µA.
Where applicable, multiple via corrections to a large
internal plane can significantly lower localized device
temperature rise.
A multi-layer printed circuit board is recommended.
Fig.1
shows
the
connections
of
most
of
the
components to the converter. Note that each individual
capacitor
could
represent
numerous
physical
capacitors. Dedicate one solid layer for a ground plane
+12VIN
and make all critical component ground connections
+5VSB
through vias placed as close to the component as
C12V
C5VSB
possible. Dedicate another solid layer as a power
CI N
plane and break this plane into smaller islands of
Q2
VOUT1
5VDLSB
VOUT3
3V3DLSB 5VDL
RT9641A/B
DLA
CBULK3
CBULK1
VSEN2
Q5
VOUT2 +5V IN
GND
DRV2
circuit layers to create power islands connecting the
filtering components (output capacitors) and the loads.
Use the remaining printed circuit layers for small signal
CHF2
CBULK2
Q3
support both the input power and output power nodes.
Use copper filled polygons on the top and bottom
CHF3
3V3DL
LOAD
Q4
LOAD
CSS
common voltage levels. Ideally, the power plane should
5VSB
LOAD
CHF1
12V
SS
Q1
wiring.
Component Selection Guidelines
Output Capacitors Selection
+3.3VI N
The output capacitors for all outputs should be
ISLAND ON POWER PLANE LAYER
selected to allow the output voltage to meet the
ISLAND ON CIRCUIT/POWER PLANE LAYER
dynamic regulation requirements of active state
VIA CONNECTION TO GROUND PLANE
operation (S0, S1). The load transient for the various
microprocessor system’s components may require high
Fig.1 Printed Circuit Board Islands
quality capacitors to supply the high slew rate (di/dt)
current demands. Thus, it is recommended that
Placement of the decoupling and bulk capacitors
should follow a placement reflecting their purpose. As
capacitors COUT1 and COUT2 should be selected for
transient load regulation.
such, the high-frequency decoupling capacitors (CHF)
should be placed as close as possible to the load they
Also, during the transition between active and sleep
are decoupling; the ones decoupling the controller
none of the power pass elements are conducting-
(C12V, C5VSB) close to the controller pins, the one
during this time the output capacitors have to supply all
decoupling the load close to the load connector or the
the output current. The output voltage drop during this
load itself (if embedded). The bulk capacitance
brief period of time can be approximated with the
(aluminum
following formula:
electrolytic
or
tantalum
capacitors)
placement is not as critical as the high-frequency
DS9641A/B-03 March 2002
states, there is a short interval of time during which
∆VOUT = IOUT x (ESROUT + tt / COUT), where
www.richtek-ic.com.tw
9
RT9641A/B
∆VOUT :
criteria for the selection of this transistor is output
output voltage drop
IOUT: output current during transition
voltage budgeting. The maximum RDS(ON) allowed at
highest junction temperature can be expressed with
COUT: output capacitor bank capacitance
the following equation:
ESROUT: output capacitor bank ESR
tt: active-to-sleep or sleep-to-active transition time
(5µS typical)
RDS(ON) MAX = (VIN MIN−VOUT MIN)/ IOUT MAX, where
VIN MIN: minimum input voltage
Since the output voltage drop is heavily dependent on
the ESR (equivalent series resistance) of the output
VOUT MIN: minimum output voltage allowed.
IOUT MAX: maximum output current
capacitor bank, the capacitors should be chosen to
The
maintain the output voltage above the lowest allowable
approximately 6V, so the logic level MOSFET is
regulation level.
gate
bias
available
for
this
MOEFET
is
prefered. The 3.3V(3.43V) VMEM power also can be
regulated from ATX 5V in order to have high quality
Input Capacitors Selection
The input capacitors for an RT9641A/B application
must have sufficiently low ESR so that the input
voltage does not dip excessively when energy is
transferred to the output capacitors.
VMEM, in such a configuration, either MOSFET or NPN
transistors can be used. While the heat dissipation
should be carefully handled.
Q4
Transistor Selection/Considerations
If a P-chanel MOSFET is used to switch the 5VSB
output of the ATX supply into the 5VDUAL output during
The RT9641A/B typically requires one P-channel or
S3 and S4/S5 states (as dictated by EN5VDL status),
PNP transistor and two N-channel power MOSFETs
then, similar to the situation where Q1 is a MOSFET,
and two bipolar NPN transistors.
the selection criteria of this device is also proper
One general requirement for selection of transistors for
voltage budgeting. The maximum rDS (ON), however,
has to be achieved with only 4.5V of VGS, so a logic
all the linear regulators/switching elements is package
selection for efficient removal of heat. The power
dissipated in a linear regulator/switching element is:
PLINEAR = IO x (VIN – VOUT)
level MOSFET needs to be selected. If a PNP device
is chosen to perform this function, it has to have a low
saturation voltage while providing the maximum sleepstate current and have current gain sufficiently high to
Select a package and heatsink that maintains the
be saturated using the minimum drive current (typically
junction temperature below the rating
20mA). A 100Ω~200Ω resistor is recommended to be
with the
maximum expected ambient temperature.
Q1
inserted between the 5VDLSB pin and Base node of
the PNP transistor for limiting the base current.
The active element on the 2.5V/3.3V (2.6V/3.43V)
Q3, Q5
VMEM output has different requirements for each the
The two N-channel MOSFETs are used to switch the
two voltage settings. In 2.5V systems utilizing RDRAM
3.3V and 5V inputs provided by the ATX supply into the
(or voltage-compatible) memory, Q1 had better to be a
3.3VDUAL and 5VDUAL outputs, respectively, while in
bipolar NPN capable of conducting the maximum
required output current and it must have a minimum
active (S0, S1) state. Similar RDS(ON) criteria apply in
these cases as well, unlike the PMOS, however, these
current gain (hfe) of 100~150 at this current and 0.7V
NMOS transistors get the benefit of an increased VGS
VCE. In such systems, the 2.5V(2.6V) output is
drive (approximately 8V and 7V respectively).
regulated from the ATX 3.3V output while in an active
Q2
state. In 3.3V systems (SDRAM or compatible) Q1 is
The NPN transistor used as sleep-state pass element
suggested to use an N-channel MOSFET, then the
on the 3.3VDUAL output must have a minimum current
MOSFET serves like a switch when it is connected to
ATX3.3V during active states (S0, S1). The main
www.richtek-ic.com.tw
10
gain of 100 at VCE = 1.5V and ICE = 500mA throughout
the in-circuit operating temperature range.
DS9641A/B-03 March 2002
RT9641A/B
Typical Application Circuit
+5VIN
+12VIN
+3.3VIN
+ C1
10µF
+5VSB
C2
1µF
+ C14
C4
1µF
5VSB
12V
Q2
2SD1802
470µF
+ C3
220µF
C5
1µF
ER800D
3V3DLSB
CEB603AL
VOUT1
3.3VDUAL
Q3
1/2 UF76113DK8
C6
1µF
DRV2
+ C7
200µF
3V3DL
VSEN2
FAULT/MSEL
R1
1K
Q1
2SD1802
RT9641A/B
5VDLSB
C8,9 +
2X150µF
S5
EN5VDL 5VDL
EN3VDL
EN3VDL
SHUTDOWN
(From Open-drain N-MOS)
SS
1µF
VOUT2
2.5VMEM
C10
1µF
Q4
MMBT2907A
R2
Q5
1/2 HUF76113DK8
S3
S5
EN5VDL
2X150µF
100
DLA
S3
+
VOUT2
3.3V/3.43 VMEM
+ C11
150µF
C12
1µF
VOUT3
5VDUAL
GND
C13
0.1µF
DS9641A/B-03 March 2002
www.richtek-ic.com.tw
11
RT9641A/B
Package Information
H
M
B
B
J
A
C
F
Symbol
www.richtek-ic.com.tw
12
D
I
Dimensions In Millimeters
Dimensions In Inches
Min
Max
Min
Max
A
9.804
10.008
0.386
0.394
B
3.810
3.988
0.150
0.157
C
1.346
1.753
0.053
0.069
D
0.330
0.508
0.013
0.020
F
1.194
1.346
0.047
0.053
H
0.178
0.254
0.007
0.010
I
0.102
0.254
0.004
0.010
J
5.791
6.198
0.228
0.244
M
0.406
1.270
0.016
0.050
DS9641A/B-03 March 2002
RT9641A/B
DS9641A/B-03 March 2002
www.richtek-ic.com.tw
13
RT9641A/B
RICHTEK TECHNOLOGY CORP.
RICHTEK TECHNOLOGY CORP.
Headquarter
Taipei Office (Marketing)
6F, No. 35, Hsintai Road, Chupei City
8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City
Hsinchu, Taiwan, R.O.C.
Taipei County, Taiwan, R.O.C.
Tel: (8863)5510047 Fax: (8863)5537749
Tel: (8862)89191466 Fax: (8862)89191465
Email: [email protected]
www.richtek-ic.com.tw
14
DS9641A/B-03 March 2002