RT7257J
Ordering Information
Pin Configurations
RT7257JCH
(TOP VIEW)
Package Type
SP : SOP-8 (Exposed Pad-Option 2)
8
7
6
5
BOOT
VIN
SS
2
3
4
EN
GND
Lead Plating System
Z : ECO (Ecological Element with
Halogen Free and Pb free)
SW
COMP
FB
9
GND
SOP-8 (Exposed Pad)
Note :
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.
Functional Pin Description
Pin No.
Pin Name
Pin Function
Bootstrap for High Side Gate Driver. Connect a 0.1μF or greater ceramic
capacitor from BOOT to SW pins.
1
BOOT
Power Input. The input Voltage range is from 4.5V to 18V. Connect two 10μF
or larger ceramic capacitors from the VIN to GND.
2
3
VIN
SW
Switch Node. Connect this pin to an external L-C filter.
4,
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
GND
9 (Exposed Pad)
Feedback Input. It is used to regulate the output of the converter to a set value
via an external resistive voltage divider.
5
6
FB
Compensation Node. COMP is used to compensate the regulation control
loop. Connect a series RC network from COMP to GND. In some cases, an
additional capacitor from COMP to GND is required.
COMP
Enable Input. A logic high enables the converter; a logic low forces the
RT7257J into shutdown mode reducing the supply current to less than 3μA.
Attach this pin to VIN with a 100kΩ pull-up resistor for automatic startup.
Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor
from SS to GND to set the soft-start period. A 0.1μF capacitor sets the
soft-start period to 13.5ms.
7
8
EN
SS
Copyright 2012 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS7257J-02 September 2012
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
