XR76121ELMTR-F Datasheet, PDF (5/19 Pages) Exar Corporation – PowerBlox 20A Synchronous Step-Down COT Regulators

Pin Configuration
TOP VIEW
SW
12
PVIN 13
XR76121
BOTTOM VIEW
11 PGND
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BST 14
EN 15
SS 16
17
AGND
8 VS
9 VIN
10 VC
BST 14
EN 15
SS 16
17
AGND
10 VCC
9 VIN
8 VSNS
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PVIN 13
11 PG
12
SW
Pin Functions
Pin Number
Pin Name
Type
Description
1
FB
A
Feedback input to feedback comparator.
2
FCCM
I
Forcing this pin logic level high forces CCM operation.
3
AGND
A
Signal ground for control circuitry. Connect to AGND pad with a short trace.
4
5
TON
A
Constant on-time programming pin. Connect with a resistor to AGND.
6
ILIM
A
Overcurrent protection programming. Connect with a resistor to SW.
7
PGOOD
OD
Power-good output. Open drain to AGND. Low Z when IC unpowered.
8
VSNS
A
Sense pin for output OVP and open FB.
9
VIN
10
VCC
A
Supply input for the regulator’s LDO. Normally connected to PV_IN.
A
The output of regulators LDO. It requires a 4.7µF V_CC bypass capacitor. For operation
using a 5V rail, VCC should be tied to VIN.
11
PGND
PWR
Ground of the power stage. Internally connected to source of the low-side MOSFET.
12
SW
PWR
Switch node. Internally it connects source of the high-side MOSFET to drain of the
low-side MOSFET.
13
PVIN
PWR
Input voltage for power stage. Internally connected to drain of the high-side MOSFET.
14
BST
A
High-side driver supply pin. Connect a 0.1µF bootstrap capacitor between BST and SW.
15
EN
16
SS
17
AGND PAD
I
Precision enable pin. Pulling this pin above 2V will enable the regulator.
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.
A
Signal ground for control circuitry.
NOTE:
A = Analog, I = Input, O = Output, OD = Open Drain, PWR = Power.
REV1A
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