RT7235 Datasheet, PDF (1/18 Pages) Richtek Technology Corporation – 5A, 18V, 650kHz, ACOTTM Synchronous Step-Down Converter

®
RT7235/36/39/40
5A, 18V, 650kHz, ACOT^TM Synchronous Step-Down Converter
General Description
The RT7235/36/39/40 is a synchronous step-down DC/
DC converter with Advanced Constant On-Time (ACOT^TM)
mode control. It achieves high power density to deliver up
to 5A output current from a 4.5V to 18V input supply. The
proprietary ACOT^TM mode offers an optimal transient
response over a wide range of loads and all kinds of ceramic
capacitors, which allows the device to adopt very low ESR
output capacitor for ensuring performance stabilization. In
addition, RT7235/36/39/40 keeps an excellent constant
switching frequency under line and load variation and the
integrated synchronous power switches with the ACOT^TM
mode operation provides high efficiency in whole output
current load range. Cycle-by-cycle current limit provides
an accurate protection by a valley detection of low side
MOSFET and external soft-start setting eliminates input
current surge during startup. Protection functions include
thermal shutdown for RT7235/36/39/40, output Under
Voltage Protection (UVP) / Over Voltage Protection (OVP)
for RT7235/36. When the UVP/OVP is triggered, the device
will enter latch mode for TSSOP-14 (Exposed Pad), and
hiccup mode for WDFN-10L 3x3.
The RT7235/36 are available in TSSOP-14 (Exposed Pad)
and WDFN-10L 3x3 packages, and the RT7235 is operated
in forced continuous conduction mode.
The RT7239/40 are available in the SOP-8 (Exposed Pad)
package, and the RT7239 is operated in forced continuous
conduction mode.
Features
z ACOT^TM Mode Enables Fast Transient Response
z 4.5V to 18V Input Voltage Range
z 5A Output Current
z 35mΩ Internal Low Site N-MOSFET
z Advanced Constant On-Time Control
z Support All Ceramic Capacitors
z Up to 95% Efficiency
z 650kHz Switching Frequency at all Load Current
(RT7235, RT7239)
z Discontinuous Operating Mode at Light Load
(RT7236, RT7240)
z Adjustable Output Voltage from 0.765V to 8V
z Adjustable Soft-Start
z Cycle-by-Cycle Current Limit
z Input Under Voltage Lockout
z Thermal Shutdown
z RoHS Compliant and Halogen Free
Applications
z Industrial and Commercial Low Power Systems
z Computer Peripherals
z LCD Monitors and TVs
z Green Electronics/Appliances
z Point of Load Regulation for High-Performance DSPs,
FPGAs, and ASICs
Simplified Application Circuit
RT7235/36/39/40
V_IN
VIN
SW
V_OUT
Enable
Power GOOD
VCC*
EN
PGOOD*
BOOT
FB
PGND
* : VCC pin for TSSOP-14 (Exposed Pad) only.
VS pin for TSSOP-14 (Exposed Pad) only.
VREG5
VS*
SS _GND*
GND pin for TSSOP-14 (Exposed Pad) only.
PGOOD pin for TSSOP-14 (Exposed Pad) and WDFN-10L 3x3 only.
Copyright ©2013 Richtek Technology Corporation. All rights reserved.
DS7235/36/39/40-00 March 2013
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
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