XR79203 Datasheet, PDF (5/19 Pages) Exar Corporation – 40V, 3A Synchronous Step-Down

Pin Configuration
XR79203
SS 1
PGOOD 2
FB 3
AGND 4
AGND 5
VIN 6
VCC 7
PGND 8
SW 9
SW 10
SW 11
SW 12
PGND 13
BST
PAD
AGND
PAD
SW
PAD
PGND PAD
41 PGND
PVIN
PAD
40 PGND
39 PGND
38 VOUT
37 VOUT
36 VOUT
35 VOUT
VOUT
PAD
34 VOUT
33 VOUT
32 VOUT
31 VOUT
30 VOUT
29 VOUT
Pin Functions
Pin Number
1
2
3
4, 5, 53, 54,
AGND Pad
6
7
8
13-19, 39-43,
PGND Pad
9-12, 20-23,
SW Pad
24-38,
VOUT Pad
45-49,
PVIN Pad
50, 51,
BST Pad
52
55
56
Pin Name
SS
PGOOD
FB
AGND
VIN
VCC
PGND
PGND
SW
VOUT
PVIN
BST
ILIM
EN/MODE
TON
Type Description
A
Soft-start pin. Connect an external capacitor between SS and AGND to program the soft-start rate based
on the 10μA internal source current.
OD, O
A
Power-good output. This open-drain output is pulled low when V_OUT is outside the regulation.
Feedback input to feedback comparator. Connect with a set of resistors to VOUT and AGND in order to
program V_OUT.
A Analog ground. Control circuitry of the IC is referenced to this pin. Connect to PGND.
PWR IC supply input. Provides power to internal LDO. Connect to PVIN pins.
PWR The output of LDO. Bypass with a 4.7μF capacitor to AGND.
PWR Controller low-side driver ground. Connect with a short trace to closest PGND pins or PGND pad.
PWR Ground of the power stage. Should be connected to the system’s power ground plane.
PWR
Switching node. It internally connects the source of the high-side FET, the drain of the low-side FET,
the inductor and bootstrap capacitor. Use thermal vias and/or sufficient PCB land area in order to heatsink
the low-side FET and the inductor.
PWR Output of the power stage. Place the output filter capacitors as close as possible to these pins.
PWR Power stage input voltage. Place the input filter capacitors as close as possible to these pins.
A
Controller high-side driver supply pin. It is internally connected to SW via a 0.1μF bootstrap capacitor.
Leave these pins floating.
A Overcurrent protection programming. Connect with a short trace to SW pins.
I
Precision enable pin. Pulling this pin above 1.9V will turn the IC on and it will operate in forced CCM. If the
voltage is raised above 3.0V, then the IC will operate in DCM or CCM depending on load.
A Constant on-time programming pin. Connect with a resistor to AGND.
NOTE:
A = Analog, I = Input, O = Output, OD = Open Drain, PWR = Power.
REV1B
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