Ap6507 – Diodes AP6507 User Manual
Page 2
AP6507
500 kHz 18V 3A SYNCHRONOUS DC/DC BUCK CONVERTER
AP6507
Document number: DS33435 Rev. 3 - 2
2 of 13
October 2011
© Diodes Incorporated
NEW PROD
UC
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Pin Descriptions
Pin #
Name
Description
1 IN
Supply Voltage. The AP6507 operates from a 4.5V to 18V input rail. C1 is needed to
decouple the input rail. Use wide PCB trace to make the connection.
2, 3
SW
Switch Output. Use wide PCB trace to make the connection.
4 BST
Bootstrap. A capacitor connected between SW and BS pins is required to form a floating
supply across the high-side switch driver.
5 EN
EN=1 to enable the chip. For automatic start-up, connect EN pin to VIN by proper EN resistor
divider as Figure 1 shows.
6 FB
Feedback. An external resistor divider from the output to GND, tapped to the FB pin, sets the
output voltage. To prevent current limit run away during a short circuit fault condition the
frequency fold-back comparator lowers the oscillator frequency when the FB voltage is below
500mV.
7
V
CC
BIAS Supply. Decouple with 0.1
μF – 0.22μF cap. The capacitance should be no more than
0.22
μF
8
GND
Exposed PAD
System Ground. This pin is the reference ground for the regulated output voltage. For this
reason care must be taken in its PCB layout. Suggested to be connected to GND with copper
and vias.
Functional Block Diagram