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
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
pull-down resistor.
AVIN (Pin 6):
Power supply for the system. Bypass this pin
with a small (0-10
, 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
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
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
) sense pin for Chan-
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
O2
during
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
O1
during
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
) sense pin for Chan-
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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