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RT8228AZQW

P1-P3P4-P6P7-P9P10-P12P13-P15
RT8228A
®
DS8228A-06 January 2014 www.richtek.com
1
©
Copyright 2014 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
Applications
z Notebook Computers
z CPU Core Supply
z Chipset/RAM Supply as Low as 0.5V
z Generic DC/DC Power Regulator
Single Synchronous Buck PWM Controller
Features
z Built in 1% 0.5V Reference Voltage
z Adjustable 0.5V to 3.3V Output Range
z Quick Load Step Response within 100ns
z 4700ppm/
°°
°°
°C Programmable Current Limit by Low
Side R
DS(ON)
Sensing
z 4.5V to 26V Battery Input Range
z Resistor Programmable Frequency
z Internal Ramp Current Limit Soft-Start Control
z Drives Large Synchronous Rectifier FETs
z Integrated Boost Switch
z Over/Under Voltage Protection
z Thermal Shutdown
z Power Good Indicator
z RoHS Compliant and Halogen Free
Ordering Information
Note :
Richtek 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.
Pin Configurations
(TOP VIEW)
WQFN-12L 2x2
General Description
The RT8228A PWM controller provides high efficiency,
excellent transient response, and high DC output accuracy
needed for stepping down high voltage batteries to
generate low voltage CPU core, I/O, and chipset RAM
supplies in notebook computers.
The constant on-time PWM control scheme handles wide
input/output voltage ratios with ease and provides 100ns
“instant-on” response to load transients while maintaining
a relatively constant switching frequency.
The RT8228A achieves high efficiency at a reduced cost
by eliminating the current sense resistor found in
traditional current mode PWMs. Efficiency is further
enhanced by its ability to drive very large synchronous
rectifier MOSFETs and enter diode emulation mode at
light load condition. The buck conversion allows this device
to directly step down high voltage batteries at the highest
possible efficiency. The Audio Skipping Mode (ASM)
setting maintains the switching frequency above 25kHz,
which eliminates noise in audio applications. The RT8228A
is intended for CPU core, chipset, DRAM, or other low
voltage supplies as low as 0.5V. The RT8228A is available
in a WQFN-12L 2x2 package.
LGATE PGOOD
UGATE
PHASE
MODE
EN
BOOT
VCC
FB
GND
TON
CS
654
12 1011
1
2
3
9
8
7
GND
13
RT8228A
Package Type
QW : WQFN-12L 2x2 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Z : ECO (Ecological Element with
Halogen Free and Pb free)
RT8228A
2
RT8228A-06 January 2014www.richtek.com
©
Copyright 2014 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
Typical Application Circuit
Marking Information
RT8228AGQW
CQ : Product Code
W : Date Code
RT8228AZQW
CQ : Product Code
W : Date Code
V
C
C
C
S
U
G
A
T
E
F
B
R
T
8
2
2
8
A
L
G
A
T
E
B
O
O
T
P
H
A
S
E
M
O
D
E
V
I
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P
G
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O
D
P
G
O
O
D
G
N
D
T
O
N
V
D
D
P
R
2
C
2
R
T
O
N
Q
1
Q
2
C
1
1
V
EN
R
6
1
0
0
k
4
.
7
µ
F
0
R
4
R
5
C
3
0
0
.
1
µ
F
4
.
5
V
t
o
2
6
V
C
4
1
0
µ
F
R
7
*
C
7
*
R
8
R
9
L
1
C
5
*
C
6
*
2
2
0
µ
F
1
0
k
1
0
k
*
:
O
p
t
i
o
n
a
l
V
O
U
T
Chip Enable
T
o
5
V
:
D
E
M
T
o
2
.
5
V
:
A
S
M
T
o
G
N
D
:
F
C
C
M
1
1
5
9
1
0
8
1
2
,
1
3
(
E
x
p
o
s
e
d
P
a
d
)
7
6
1
2
3
4
CQW CQW
RT8228A
3
RT8228A-06 January 2014 www.richtek.com
©
Copyright 2014 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
Pin No. Pin Name Pin Function
1 LGATE Gate Drive Output for Low Side External MOSFET.
2 PHASE
External Inductor Connection Pin for PWM Converter. It behaves as the current
sense comparator input for Low Side MOSFET R
DS(ON)
sensing and reference
voltage for on time generation.
3 UGATE Gate Drive Output for High Side External MOSFET.
4 BOOT
Supply Input for High Side Driver. Connect through a capacitor to the floating
node (PHASE) pin.
5 VCC
Control Voltage Input. Provides the power for the buck controller, the low side
driver and the bootstrap circuit for high side driver. Bypass to GND with a 4.7μF
ceramic capacitor.
6 FB
V
OUT
Feedback Input. Connect FB to a resistive voltage divider from V
OUT
to
GND to adjust the output from 0.5V to 3.3V
7 MODE
Pull Down to GND for Forced CCM Mode.
Pull Up to 2.5V for Audio Skipping Mode (ASM).
Pull Up to 5V for Diode Emulation Mode (DEM).
8 EN PWM Chip Enable. Pull low to GND to disable the PWM.
9 PGOOD Open Drain Power Good Indicator. High impedance indicates power is good.
10 CS
Current Limit Threshold Setting Input. Connect a setting resistor to GND and the
current limit threshold is equal to 1/10 of the voltage at this pin.
11 TON On-time Setting. Connect a resistor between this pin and V
IN
.
12,
13 (Exposed Pad)
GND
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
Functional Pin Description
Function Block Diagram
Min. T
OFF
QTRIG
1-SHOT
+
-
COMP
0.5V V
REF
S1 Q
Latch
S1 Q
Latch
+
-
OV
-
+
UV
125% V
REF
70% V
REF
+
-
125% V
REF
Thermal
Shutdown
DEM/FCCM/ASM
DRV
DRV
On-time
Compute
1-SHOT
FB
VCC
UGATE
PHASE
PGOOD
GND
LGATE
TON
BOOT
TRIG
EN
R
QS
X(-1/10)
+
-
PWM
MODE
+
-
90% V
REF
SS
Timer
POR
CS
VCC
PHASE
10µA
PSR
P1-P3P4-P6P7-P9P10-P12P13-P15

RT8228AZQW

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Description:
IC REG CTRLR BUCK 12WQFN
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New from this manufacturer.
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