RT5771B Step-Down Converter Datasheet

RT5771B Datasheet, PDF, Equivalent


Part Number

RT5771B

Description

Synchronous Step-Down Converter

Manufacture

Richtek

Total Page 13 Pages
Datasheet
Download RT5771B Datasheet


RT5771B
®
RT5771B
3A, 1MHz, Synchronous Step-Down Converter
General Description
The RT5771B is a high efficiency synchronous, step-down
DC-DC converter. Its input voltage ranges from 2.7V to
5.5V that provides an adjustable regulated output voltage
from 0.6V to VIN while delivering up to 3A of output current.
The internal synchronous low on-resistance power
switches increase efficiency and eliminate the need for
an external Schottky diode. The switching frequency is
fixed internally at 1MHz. The 100% duty cycle provides
low dropout operation, hence extending battery life in
portable systems. Current mode operation with internal
compensation allows the transient response to be
optimized over a wide range of loads and output capacitors.
The RT5771B is available in a WDFN-10L 3x3 package.
Ordering Information
RT5771B
Package Type
QW : WDFN-10L 3x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
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.
Marking Information
M3=YM
DNN
M3= : Product Code
YMDNN : Date Code
Features
High Efficiency : Up to 95%
High Efficiency at Light Load
Low RDS(ON) Power Switches : 69mΩ/49mΩ
Fixed Frequency : 1MHz
No Schottky Diode Required
Internal Compensation
0.6V Reference Allows Low Output Voltage
Low Dropout Operation : 100% Duty Cycle
OCP, UVP, OTP
Applications
Portable Instruments
Battery Powered Equipment
Notebook Computers
Distributed Power Systems
IP Phones
Digital Cameras
Pin Configuration
(TOP VIEW)
FB 1
VCC 2
VIN 3
GND 4
GND 5
10 EN
9 PGOOD
8 NC
7 SW
11 6 SW
WDFN-10L 3x3
Copyright ©2019 Richtek Technology Corporation. All rights reserved.
DS5771B-01 June 2019
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1

RT5771B
RT5771B
Typical Application Circuit
VIN
PGOOD
Chip Enable
CIN
10µF
R3
100k
L
RT5771B
1.5µH
3 VIN
SW 6, 7
2 VCC
C1
1µF
9 PGOOD
FB 1
R1
6.2k
R2
8.2k
10 EN
GND
4, 5,
11 (Exposed
Pad)
CFF
560pF
VOUT
COUT 1.05V
22µF x 2
VOUT (V)
3.3
2.5
1.8
1.5
1.2
1
Table 1. Recommended Component Selection
R1 (k)
37
R2 (k)
8.2
CFF (pF)
430
L (H)
2
26 8.2 430 2
16.5 8.2 510 1.5
12.3 8.2 560 1.5
8.2 8.2 620 1.5
5.6 8.2 680 1.5
COUT (F)
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
Functional Pin Description
Pin No.
Pin Name
Pin Function
1 FB
Feedback input. This pin receives the feedback voltage from a resistive
voltage divider connected across the output.
2
VCC
Supply voltage input. Decouple this pin to GND with at least 1F ceramic cap.
3 VIN Power input. Decouple this pin to GND with at least 10F ceramic cap.
4, 5,
11 (Exposed Pad)
GND
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
6, 7 SW
Switch node. Connect this pin to the inductor.
8 NC No internal connection.
Power good indicator. This pin is an open drain logic output. The PGOOD will
9
PGOOD
be pulled to ground when the output voltage is less than 90% of the target
output voltage.
10 EN
Enable control input. Pull high the EN pin to turn on the converter.
Copyright ©2019 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS5771B-01 June 2019


Features ® RT5771B 3A, 1MHz, Synchronous Step-D own Converter General Description The RT5771B is a high efficiency synchrono us, step-down DC-DC converter. Its inpu t voltage ranges from 2.7V to 5.5V that provides an adjustable regulated outpu t voltage from 0.6V to VIN while delive ring up to 3A of output current. The in ternal synchronous low on-resistance po wer switches increase efficiency and el iminate the need for an external Schott ky diode. The switching frequency is fi xed internally at 1MHz. The 100% duty c ycle provides low dropout operation, he nce extending battery life in portable systems. Current mode operation with in ternal compensation allows the transien t response to be optimized over a wide range of loads and output capacitors. T he RT5771B is available in a WDFN-10L 3 x3 package. Ordering Information RT57 71B Package Type QW : WDFN-10L 3x3 (W- Type) Lead Plating System G : Green (Ha logen Free and Pb Free) Note : Richtek products are :  RoHS compliant and compatible with the current.
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