MIC26903 Datasheet, PDF (2/31 Pages) Micrel Semiconductor – 28V, 9A Hyper Light Load Synchronous DC/DC Buck Regulator

Micrel, Inc.
MIC26903
Ordering Information
Part Number
MIC26903YJL
Voltage
Adjustable
Switching Frequency
600kHz
Junction Temperature
Range
–40°C to +125°C
Package
28-Pin 5mm × 6mm MLF^®
Lead Finish
Pb-Free
Pin Configuration
28-Pin 5mm x 6mm MLF^® (YJL)
Pin Description
Pin Number Pin Name
1
PVDD
3
NC
4, 9, 10, 11, 12
SW
2, 5, 6, 7, 8, 21
PGND
13,14,15,
16,17,18,19
20
PVIN
BST
Pin Function
5V Internal Linear Regulator (Output): PVDD supply is the power MOSFET gate drive supply
voltage and created by internal LDO from V_IN. When V_IN < +5.5V, PVDD should be tied to PVIN
pins.
A 2.2µF ceramic capacitor from the PVDD pin to PGND (pin 2) must be place next to the IC.
No Connect.
Switch Node (Output): Internal connection for the high-side MOSFET source and low-side
MOSFET drain. Due to the high speed switching on this pin, the SW pin should be routed away
from sensitive nodes.
Power Ground. PGND is the ground path for the MIC26903 buck converter power stage. The
PGND pins connect to the low-side N-Channel internal MOSFET gate drive supply ground, the
sources of the MOSFETs, the negative terminals of input capacitors, and the negative terminals of
output capacitors. The loop for the power ground should be as small as possible and separate
from the Signal ground (SGND) loop.
High-Side N-internal MOSFET Drain Connection (Input): The PV_IN operating voltage range is from
4.5V to 26V. Input capacitors between the PVIN pins and the power ground (PGND) are required
and keep the connection short.
Boost (output): Bootstrapped voltage to the high-side N-channel MOSFET driver. A Schottky diode
is connected between the PVDD pin and the BST pin. A boost capacitor of 0.1μF is connected
between the BST pin and the SW pin. Adding a small resistor at the BST pin can slow down the
turn-on time of high-side N-Channel MOSFETs.
July 2011
2
M9999-071311-A