RT2652
Functional Pin Description
Pin No.
Pin Name
Pin Function
Enable Control Input. Pull high to turn on. Do not float.
Power Input. Decouple this pin to GND with a 22μF ceramic capacitor at least.
Analog Ground.
1
EN
2, 3
VIN
4, 6
AGND
Feedback Voltage Input. This pin receives the feedback voltage from an external
resistive divider connected across the output.
5
FB
7, 8
LX
Power MOSFET Switch Node. Connect this pin to the inductor.
9, 10,
11 (Exposed Pad)
Power Ground. The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
PGND
Function Block Diagram
VIN
EN
POR
ISEN
EN
Slope
Comp.
OSC
0.6V
EA
Output
Clamp
FB
OC Limit
SS
Driver
LX
0.2V
Control Logic
UV
NISEN
PGND
AGND
OTP
N-MOSFET Limit
Operation
high side MOSFET turns off, the synchronous power
switch (N-MOSFET) turns on until either the bottom current
limit is reached or the beginning of the next cycle. The
operating frequency is set by the internal oscillator at
1.2MHz. In VIN larger than 6V condition, the high side
MOSFET is turned off and the low side MOSFET is
switched on until either the VIN over voltage condition is
cleared or the low side MOSFET's current limit is reached.
In FB larger than 1.05V condition, the high side MOSFET
turns off, and the low side MOSFET turns on, and IC is
latched until restarted.
The RT2652 is a monolithic, constant-frequency, current
mode step-down DC/DC converter. During normal
operation, the internal high side MOSFET is turned on at
the beginning of each cycle. Current in the inductor
increases until the peak inductor current reaches the value
defined by the internal error amplifier. The error amplifier
adjusts the voltage of its output by comparing the feedback
signal from a resistor divider on the FB pin with an internal
0.6V reference. When the load current increases, it causes
a reduction in the feedback voltage relative to the reference.
The error amplifier raises its output voltage until the average
inductor current matches the new load current. When the
Copyright 2012 Richtek Technology Corporation. All rights reserved.
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is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS2652-00 November 2012
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
