RT7275/76
Functional Pin Description
Pin No.
Pin Name
Pin Function
TSSOP-14
(Exposed Pad)
WDFN-10L 3x3
Optional Output Voltage Discharge Connection. This open drain
output connects to ground when the device is disabled. If output
voltage discharge is desired, connect VOUT to the output
voltage.
1
2
3
--
VOUT
FB
Feedback Input Voltage. Connect FB to the midpoint of the
external feedback resistive divider to sense the output voltage.
Place the resistive divider within 5mm from the FB pin. The IC
2
3
regulates V at 0.765V (typical).
FB
Linear Regulator Output. PVCC is the output of the internal
5.1V linear regulator powered by VIN (WDFN-10L 3x3) or VINR
(TSSOP-14 (Exposed Pad)). Connect a 1μF ceramic capacitor
from PVCC to ground.
PVCC
Soft-Start Control. Connect an external capacitor between this
pin and ground to set the soft-start time.
4
5
4
SS
--
GND
Analog Ground.
Open Drain Power-good Output. PGOOD connects to PGND
6
7
5
1
PGOOD
EN
whenever V
(typical).
is less than 90% of its regulation threshold
FB
Enable Control Input. Connect EN to a logic-high voltage to
enable the IC or to a logic-low voltage to disable. Do not leave
this high impedance input unconnected.
Power Ground. PGND connects to the Source of the internal
N-channel MOSFET synchronous rectifier and to other power
ground nodes of the IC. The exposed pad and the 2 PGND pins
(TSSOP-14 (Exposed Pad)) should be well soldered to the
input and output capacitors and to a large PCB area for good
power dissipation.
8, 9, 15
(Exposed pad)
11 (Exposed pad) PGND
Switching Node. SW is the Source of the internal N-channel
MOSFET switch and the Drain of the internal N-channel
MOSFET synchronous rectifier. Connect SW to the inductor
with a wide short PCB trace and minimize its area to reduce
EMI.
10, 11
6, 7
SW
Bootstrap Supply for High Side Gate Driver. Connect a 0.1μF
capacitor between BOOT and SW to power the internal gate
driver.
12
13
8
BOOT
VIN
Power Input. VIN is the Drain of the internal N-channel
MOSFET switch. Connect VIN to the input capacitor. For the
WDFN-10L 3x3 package, VIN also supplies power to the
internal linear regulator.
9, 10
Internal Linear Regulator Supply Input. For the TSSOP-14
(Exposed Pad) package, VINR supplies power for the internal
linear regulator that powers the IC. Connect VIN to the input
voltage and bypass to ground with a 0.1μF ceramic capacitor.
14
--
VINR
Copyright 2013 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
DS7275/76-00 January 2013
www.richtek.com
9
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