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PDF ( 数据手册 , 数据表 ) RT8857A

零件编号 RT8857A
描述 4/3/2/1-Phase PWM Controller
制造商 Richtek
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RT8857A 数据手册, 描述, 功能
RT8857/A
4/3/2/1-Phase PWM Controller with Embedded Drivers
for CPU Core Power Supply
General Description
Features
The RT8857/A is a 4/3/2/1-phase synchronous buck
controller with 2 integrated MOSFET drivers for Intel
VR11.1/VR10.x and AMD K8/K8_M2 CPUs power
application. RT8857/A uses differential inductor DCR
current sense to achieve phase current balance and active
voltage positioning. Other features include adjustable
operating frequency, adjustable soft start, power good
indication, external error-amp compensation, over voltage
protection, over current protection, VRHOT sensing and
IMON for various applications. RT8857/A comes to a small
footprint with WQFN-48L 7x7 package
Ordering Information
RT8857/A
Package Type
QW : WQFN-48L 7x7 (W-Type)
Operating Temperature Range
G : Green (Halogen Free with Commer-
cial Standard)
12V Power Supply Voltage
4/3/2/1-Phase Power Conversion
2 Embedded MOSFET Drivers
Internal Regulated 5V Output
VID table for INTEL VR11.1/VR10.x and AMD K8/
K8_M2 CPUs
Continuous Differential Inductor DCR Current Sense
Adjustable Soft Start
Adjustable Frequency
Power Good Indication
Adjustable Over Current Protection
Over Voltage Protection
VRHOT Sensing with External Thermistor
IMON Output Current Indication
Power State Indicator (PSI)
Support MOSFET Power Stage Input Voltage (VIN)
Down to 5V (RT8857A Only)
Small 48-Lead WQFN Package
RoHS Compliant and Halogen Free
Support VIN : 5/12V
Support VIN : 12V
Pin Configurations
Note :
VIN is the input voltage of MOSFET power stage.
Richtek Green products are :
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
Applications
Desktop CPU Core Power
Low Voltage, High Current DC/ DC Converter
(TOP VIEW)
48 47 46 45 44 43 42 41 40 39 38 37
FBRTN 1
36
QR1 2
35
QR2 3
34
SS/EN 4
33
COMP 5
32
FB 6
OFS 7
GND
31
30
RT 8
29
ADJ 9
28
IMAX 10
IMAXPSI 11
49 27
26
IMONFB 12
25
PWRGD
BOOT1
UGATE1
PHASE1
LGATE1
VCC12
LGATE2
PHASE2
UGATE2
BOOT2
PWM3
PWM4
13 14 15 16 17 18 19 20 21 22 23 24
WQFN-48L 7x7
DS8857/A-00 February 2009
www.richtek.com
1
Free Datasheet http://www.datasheet.in/







RT8857A pdf, 数据表
RT8857/A
VID4
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
VID3
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
VID2
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Pin Name
VID1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
VID0
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
VID5
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
VID6
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Nominal Output Voltage DACOUT
1.11250V
1.10625V
1.10000V
1.09375V
OFF
OFF
OFF
OFF
1.08750V
1.08125V
1.07500V
1.06875V
1.06250V
1.05625V
1.05000V
1.04375V
1.03750V
1.03125V
1.02500V
1.01875V
1.01250V
1.00625V
1.00000V
0.99375V
0.98750V
0.98125V
0.97500V
0.96875V
0.96250V
0.95625V
0.95000V
0.94375V
0.93750V
0.93125V
0.92500V
0.91875V
0.91250V
0.90625V
0.90000V
www.richtek.com
8
To be continued
DS8857/A-00 February 2009
Free Datasheet http://www.datasheet.in/







RT8857A equivalent, schematic
RT8857/A
Parameter
Symbol
Reference Voltage accuracy
DAC Accuracy
Error Amplifier
DC Gain
Ga in-B and widt h
Slew Rate
Output voltage range
Max Current
Power Sequence
PWRGD Low Voltage
Soft-Start Delay
VBOOT Duration
A DC
GBW
SR
V COM P
IEA_S LEW
V PGOOD
TD1
TD3
PWRGD Delay
TD5
Current Sense Amplifier
Max Current
Input Offset Voltage
Running Frequency
RT Pin Voltage
Ramp Slope
Soft Start
Soft Start Current
VID Change Current
Gate Driver
IGMMAX
V OSCS
fOSC
V RT
V RAM P
ISS1
ISS2
UGATE Drive Source
RUGATEsr
UGATE Drive Sink
LGATE Drive Source
LGATE Drive Sink
Protec ti on
Over-Voltage Threshold
Over-Current Threshold
Dynamic Characteristic
UGATE Rise Time
UGATE Fall Time
LGATE Rise Time
LGATE Fall Time
RUGATEsk
RLGATEsr
RLGATEsk
V OVP
V OCP
trUGATE
tfUGATE
trLGATE
tfLGATE
www.richtek.com
16
C onditions
1V to 1.6V
0.8V to 1V
0.5V to 0.8V
No Load
CLOAD = 10pF
CLOAD = 10pF
Slew
IPWRGD = 4mA
Measured the time form VBOOT change
to PWRGD = 1
VCSP = 1.3V
Sink Current from CSN
RRT = 40k
RRT = 40k
RRT = 40k
Slew
Slew
BOOT PHASE = 8V
250mA Source Current
BOOT PHASE = 8V
250mA Sink Current
VLGATE = 8V
250mA Sink Current
Sweep FB Voltage, VFB VEAP
Sweep IMAX Voltage, VIMAX VADJ
Ciss = 3000p
Min Typ Max Unit
0.5
5
8
-- +0.5 %
-- +5 mV
-- +8 mV
-- 80 -- dB
-- 10 -- MHz
10 -- -- V/us
0.5 3.6 V
300 --
-- uA
-- -- 0.4 V
-- 2 -- ms
-- 0.8 -- ms
-- 1.6 -- ms
100 --
-- uA
2 0 +2 mV
270 300 330 kHz
0.76 0.8 0.84 V
-- 22 -- %/V
12 16 20 uA
120 160 200 uA
-- 1 --
-- 1 --
-- 1 --
-- 0.8 --
125 150 175 mV
10 0 +10 mV
-- 15 -- ns
-- 10 -- ns
-- 15 -- ns
-- 10 -- ns
To be continued
DS8857/A-00 February 2009
Free Datasheet http://www.datasheet.in/










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