Datasheet

OUT
FB
GND
NC
RT/CLK
PGND
NR
LDOEN
NC
PWRGD
BOOT
PH
2
3
4
5
6
18
17
16
15
14
Thermal
Pad
OUT
1
24
19
PGND
VSENSE
LDOIN
LDOIN
COMP
7
12 13
PVIN
8
PVIN
9
VIN
10
11
PH
EN
SS
20
21
22
23
TPS54120
www.ti.com SBVS180C –JANUARY 2012–REVISED JUNE 2012
PIN CONFIGURATION
RGY PACKAGE
QFN-24
(TOP VIEW)
PIN DESCRIPTIONS
PIN
NAME NO. DESCRIPTION
A bootstrap capacitor is required between the BOOT and PH pins. The voltage on this capacitor carries the gate
BOOT 18
drive voltage for the high-side MOSFET of the dc-dc converter.
DC-DC error amplifier output, and input to the output switch current comparator. Connect frequency compensation to
COMP 13
this pin.
Active-high enable pin for dc-dc converter. Float this pin to enable. Adjust the input undervoltage lockout with two
EN 15
resistors.
FB 3 This pin is the input to the control-loop error amplifier of the LDO and is used to set its output voltage.
GND 4 LDO ground
Driving this pin high turns on the LDO regulator. Driving this pin low puts the LDO regulator into shutdown mode.
LDOEN 21
The EN pin must not be left floating and can be connected to LDOIN if not used.
LDOIN 23, 24 LDO input
NC 5, 20 No internal connection
LDO noise reduction pin. Connect an external capacitor between this pin and ground to reduce output noise to very
NR 22
low levels, and slow down the VOUT ramp (RC soft-start) of the LDO.
OUT 1, 2 LDO output. A 4.7-µF or larger capacitor is required for stability.
PGND 7, 8 Return for the dc-dc control circuitry and low-side power MOSFET of the dc-dc converter.
PH 16, 17 DC-DC converter switch node
PVIN 9, 10 DC-DC converter power input. Supplies the power switches of the dc-dc converter.
Open-drain power good fault pin for the dc-dc converter output. Asserts low as a result of thermal shutdown,
PWRGD 19
undervoltage, overvoltage, EN pin shutdown, or during soft-start of the dc-dc converter.
Automatically selects between RT mode and CLK mode. An external timing resistor adjusts the switching frequency
RT/CLK 6
of the device. In CLK mode, the device synchronizes to an external clock.
DC-DC converter soft-start pin. Connect an external capacitor to this pin to set the internal reference voltage rise
SS 14
time on the dc-dc converter. The voltage on this pin overrides the internal reference on the dc-dc converter.
VIN 11 Supplies the control circuitry of the dc-dc converter.
VSENSE 12 Inverting input of the g
M
error amplifier of the dc-dc converter.
GND; for best noise performance, the thermal pad should be connected to the LDO GND and to a large ground pad
Thermal pad
for thermal dissipation.
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