Datasheet

FB
PGOOD
COMP
NC
PVIN
PVIN
SW
SS/TRK
AVIN
VCC
EN
PGND
PGND
SW
AGND
NC
EP
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
LM20125
SNVS525E –OCTOBER 2007–REVISED MARCH 2013 www.ti.com
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
Connection Diagram
Top View
See Package Number PWP0016A
PIN DESCRIPTIONS
Pin # Name Description
1 SS/TRK Soft-Start or Tracking control input. An internal 5 µA current source charges an external capacitor to set the
soft-start ramp rate. If driven by a external source less than 800 mV, this pin overrides the internal reference
that sets the output voltage. If left open, an internal 1ms soft-start ramp is activated.
2 FB Feedback input to the error amplifier from the regulated output. This pin is connected to the inverting input of
the internal transconductance error amplifier. An 800 mV reference connected to the non-inverting input of the
error amplifier sets the closed loop regulation voltage at the FB pin.
3 PGOOD Power good output signal. Open drain output indicating the output voltage is regulating within tolerance. A
pull-up resistor of 10 kΩ to 100 kΩ is recommend for most applications.
4 COMP External compensation pin. Connect a resistor and capacitor to this pin to compensate the device.
5,16 NC These pins must be connected to GND to ensure proper operation.
6,7 PVIN Input voltage to the power switches inside the device. These pins should be connected together at the device.
A low ESR capacitor should be placed near these pins to stabilize the input voltage.
8,9 SW Switch pin. The PWM output of the internal power switches.
10,11 PGND Power ground pin for the internal power switches.
12 EN Precision enable input for the device. An external voltage divider can be used to set the device turn-on
threshold. If not used the EN pin should be connected to PVIN.
13 VCC Internal 2.7V sub-regulator. This pin should be bypassed with a 1 µF ceramic capacitor.
14 AVIN Analog input supply that generates the internal bias. Must be connected to VIN through a low pass RC filter.
15 AGND Quiet analog ground for the internal bias circuitry.
EP Exposed Pad Exposed metal pad on the underside of the package with a weak electrical connection to ground. It is
recommended to connect this pad to the PC board ground plane in order to improve heat dissipation.
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Product Folder Links: LM20125