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RT7251A/B
1.5A, 17V, 340/800kHz Synchronous Step-Down Converter
General Description
The RT7251A/B is a high efficiency, monolithic synchronous step-down DC-DC converter that can operate at 340kHz/800kHz, while delivering up to 1.5A output current from a 4V to 17V input supply. The RT7251A/B's current mode architecture allows the transient response to be optimized. Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. Fault conditions also include output under voltage protection, output over voltage protection and thermal shutdown. The low current (<5μA) shutdown mode provides output disconnection, enabling easy power management in battery-powered systems. The RT7251A/B is available in a WDFN-8L 2x2 package.
Ordering Information
RT7251A/B
Package Type QW : WDFN-8L 2x2 (W-Type)
Lead Plating System Z : ECO (Ecological Element with
Halogen Free and Pb free)
Note :
A : 340kHz B : 800kHz
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
RT7251AZQW
03 : Product Code
03W
W : Date Code
Features
4V to 17V Input Voltage Range 1.5A Output Current Internal N-MOSFETs Current Mode Control Fixed Frequency Operation : 340kHz/800kHz Output Adjustable from 0.8V to 12V Up to 95% Efficiency Internal Compensation Stable with Low ESR Ceramic Output Capacitors Cycle-by-Cycle Over Current Protection Input Under Voltage Lockout Output Under Voltage Protection Output Over Voltage Protection Power Good Indicator Thermal Shutdown Protection RoHS Compliant and Halogen Free
Applications
Industrial and Commercial Low Power Systems Computer Peripherals LCD Monitors and TVs Green Electronics/Appliances Point of Load Regulation for High-Performance DSPs,
FPGAs, and ASICs
Pin Configuration
(TOP VIEW)
SW 1 VIN 2 BOOT 3 EN 4
GND
8 GND 7 GND 6 PGOOD 9 5 FB
WDFN-8L 2x2
RT7251BZQW
70 : Product Code
70W
W : Date Code
Copyright ©2023 Richtek Technology Corporation. All rights reserved. DS7251A/B-04 April 2023
is a registered trademark of Richtek Technology Corporation.
www.richtek.com 1
RT7251A/B
Typical Application Circuit
VIN 4V to 17V
CIN 10µF
PGOOD Chip Enable
RT7251A
2 VIN
BOOT 3
6 PGOOD 4 EN
SW 1 FB 5
7, 8, 9 (Exposed Pad) GND
CBOOT 10nF
L 15µH
R1 110k R2 36k
VOUT 3.3V 1.5A COUT 22µF x 2
VIN 4V to 17V
CIN 10µF
PGOOD Chip Enable
RT7251B
2 VIN
BOOT 3
6 PGOOD 4 EN
SW 1 FB 5
7, 8, 9 (Exposed Pad) GND
CBOOT 10nF
L 6.8µH
R1 47k R2 15k
VOUT 3.3V 1.5A COUT 22µF x 2
Table 1. Recommended Component Selection RT7251A
VOUT (V) L (H) R1 (k) R2 (k) COUT (F)
1.2
4.7
110
220
22 x 2
2.5
10
110
51
22 x 2
3.3
15
110
36
22 x 2
5
22
120
22
22 x 2
RT7251B VOUT (V) 1.2 2.5 3.3 5
L (H) 3.6 4.7 6.8 10
R1 (k) 47 47 47 62
R2 (k) 91 22 15 12
COUT (F) 22 x 2 22 x.