Connection Diagram

TOP VIEW

20117202

28-Lead Plastic (TSSOP Exposed Pad)

See NS Package Number MXA28A

Pin Descriptions

SW1 (Pins 1, 28): The switch node pins for Channel 1.

Connect the Channel 1 output inductor to these pins.

PVIN1 (Pins 2, 3): Input voltage supply for the Channel 1

switch. In a split-rail system, this supply should not exceed

the voltage at the AVIN pin.

PG1 (Pin 4): Open drain Power Good flag for Channel 1.

When this pin voltage is high, the output voltage is ready to

deliver power to the load. Connect to AVIN through a 10k

Ω

pull-up resistor.

EN1 (Pin 5): Channel 1 logic enable. Input to a CMOS

Schmitt trigger. Set this input high for normal operation.

When low, Channel 1 is in shutdown mode. Connect to

ground through a 100k

Ω pull-down resistor.

AVIN (Pin 6): Power supply for the system. Bypass this pin

with a small (0-10

Ω, 1 µF) filter if it is connected to the same

rail as PVIN.

SYNC (Pin 7): PWM frequency adjust. Connect a PWM

clock to this pin. If unused, connect this pin to ground.

NC (Pin 8): No internal connection. This pin should be

connected to ground.

AGND (Pin 9): Ground pin for the signal level circuitry. Must

be connected to the system ground.

EN2 (Pin 10): Channel 2 logic enable. Input to a CMOS

Schmitt trigger. Set this input high for normal operation.

When low, Channel 2 is in shutdown mode. Connect to

ground through a 100k

Ω pull-down resistor

PG2 (Pin 11): Open drain Power Good flag for Channel 2.

When this pin level is high, the Output voltage is ready to

deliver power to the load. Connect to AVIN through a 10k

Ω

pull-up resistor.

PVIN2 (Pin 12,13): Input voltage supply for the Channel 2

switch. In a split-rail system, this supply should not exceed

the voltage at the AVIN pin.

SW2 (Pin 14, 15): The switch node pins for Channel 2.

Connect the Channel 2 output inductor to these pins.

PGND2 (Pin 26, 27): Ground pins for the high current cir-

cuitry. Must be connected to the system ground.

SNS2 (Pin 18): The output voltage (V

nel 2. Connect this pin directly to the load.

FB2 (Pin 19): The input to the error amplifier of Channel 2.

COMP2 (Pin 20): The output of the Channel 2 error ampli-

fier.

SS2 (Pin 21): Soft start pin for Channel 2. Connect a small

capacitor to this pin to control the slew rate of V

start-up.

SS1 (Pin 22): Soft start pin for Channel 1. Connect a small

capacitor to this pin to control the slew rate of V

start-up.

COMP1 (Pin 23): The output of the Channel 1 error ampli-

fier.

FB1 (Pin 24): The input to the error amplifier of Channel 1.

SNS1 (Pin 25): The output voltage (V

nel 1. Connect this pin directly to the load.

PGND2 (Pins 16, 17): Ground pins for the high current

circuitry. Must be connected to the system ground.

EXPOSED PAD: Connect to power ground.

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