RT2652
Functional Pin Description
Pin No.
1
2, 3
4, 6
5
Pin Name
EN
VIN
AGND
FB
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.
Feedback Voltage Input. This pin receives the feedback voltage from an external
resistive divider connected across the output.
Power MOSFET Switch Node. Connect this pin to the inductor.
Power Ground. The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
7, 8
LX
9, 10,
PGND
11 (Exposed Pad)
Function Block Diagram
EN
EN
OSC
0.6V
FB
EA
Output
Clamp
OC Limit
SS
Driver
0.2V
LX
POR
Slope
Comp.
ISEN
VIN
UV
Control Logic
AGND
OTP
NISEN
N-MOSFET Limit
PGND
Operation
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
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.
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS2652-00
November 2012
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
