1.5MHz, 700mA Synchronous Step-Down Converter
◼ General Description
The OCP2157 is a 1.5MHz constant frequency; slope
compensated current mode PWM step-down
converter. The device integrates a main switch and a
synchronous rectifier for high efficiency without an
external Schottky diode. It is ideal for powering
portable equipment that runs from a single cell
lithium-Ion (Li+) battery. The OCP2157 can supply
700mA of load current from a 2.5V to 5.5V input
voltage. The output voltage can be regulated as low as
0.6V. The OCP2157 can also run at 100% duty cycle
for low dropout operation, extending battery life in
portable system. Idle mode operation at light loads
provides very low output ripple voltage for noise
The OCP2157 is offered in a low profile (1mm) 5-pin,
SOT package, and is available in an adjustable version
and fixed output voltage of 1.2V, 1.5V and 1.8V.
⚫ Cellular and Smart Phones
⚫ MP3 Player
⚫ Digital Still and Video Cameras
⚫ Portable instruments
⚫ Microprocessors and DSP Core Supplies
⚫ Wireless and DSL Modems
⚫ High Efficiency : Up to 96%
⚫ 1.5MHz Constant Switching Frequency
⚫ 700mA Output Current at VIN=3.0V
⚫ Integrated Main switch and synchronous rectifier.
No Schottky Diode Required
⚫ 2.5V to 5.5V Input Voltage Range
⚫ Output Voltage as low as 0.6V
⚫ 100% Duty Cycle in Dropout
⚫ Low Quiescent Current : 300μA
⚫ ＜1μA Shutdown Current
⚫ Slope Compensated Current Mode Control for
Excellent Line and Load Transient Response
⚫ Short Circuit and Thermal Fault Protection
⚫ Space Saving 5-pin Thin SOT23 package
◼ Pin Configuration
◼ Pin Description
Supply Input Pin. Must be closely decoupled to GND, pin2, with a 2.2μF or
greater ceramic capacitor.
Regulator Enable control input. Drive RUN above 1.5V to turn on the part.
Drive RUN below 0.3V to turn it off. In shutdown, all functions are disable
drawing ＜1μA supply current. Do not leave RUN floating.
VFB (OCP2157): Feedback Input Pin. Connected FB to the center point of
the external resistor divider. The feedback threshold voltage is 0.6V.
VOUT (OCP2157-1.2/1.5/1.8): Output Voltage Feedback Pin. An internal
resistive divider divides the output voltage down for comparison to the
internal reference voltage.
Power Switch Output. It is the Switch node connection to inductor. This pin
connects to the drains of the internal P-CH and N-CH MOSFET switches.
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Rev. 1.3 Feb .27, 2018