REV2.0

Page2

BL8521

5.5V, 1.4MHz, 3A Synchronous Buck Converter

BLOCK DIAGRAM

PIN CONFIGURATION

DFN3x3-10

PIN NO. PIN NAME

PIN FUNCTION

1

SHDN/RT

Oscillator Resistor Input. Connecting a resistor to ground from this pin sets the switching

frequency. Forcing this pin to VDD causes the device to be shut down.

2

GND

Signal Ground. All small-signal components and compensation components should connect to

this ground, which in turn connects to PGND at one point.

3,4

LX

Internal Power MOSFET Switches Output. Connect this pin to the inductor.

5

PGND

Power Ground. Connect this pin close to the negative terminal of CIN and COUT.

6,7

PVDD

Power Input Supply. Decouple this pin to PGND with a capacitor.

8

VDD

Signal Input Supply. Decouple this pin to GND with a capacitor. Normally VDD is equal to

PVDD.

9

FB

Feedback Pin. This pin Receives the feedback voltage from a resistive divider connected

across the output.

10

COMP

Error Amplifier Compensation Point. The current comparator threshold increases with this

control voltage. Connect external compensation elements to this pin to stabilize the control

loop.