MIC24055 Datasheet, PDF (3/29 Pages) Micrel Semiconductor – 12V, 12A High-Efficiency Buck Regulator

Micrel, Inc.
MIC24055
Pin Description (Continued)
Pin Number
22
23
24
25
26
27
28
Pin Name
CS
SGND
FB
PG
EN
VIN
VDD
Pin Function
Current-Sense Input. The CS pin senses current by monitoring the voltage across the low-side
MOSFET during the OFF-time. The current sensing is necessary for short circuit protection. In order
to sense the current accurately, connect the low-side MOSFET drain to SW using a Kelvin
connection. The CS pin is also the high-side MOSFET’s output driver return.
Signal Ground. SGND must be connected directly to the ground planes. Do not route the SGND pin
to the PGND Pad on the top layer (see PCB Layout Guidelines for details).
Feedback Input. Input to the transconductance amplifier of the control loop. The FB pin is regulated
to 0.8V. A resistor divider connecting the feedback to the output is used to adjust the desired output
voltage.
Power Good Output. Open Drain output. The PG pin is externally tied with a resistor to VDD. A high
output is asserted when VOUT > 92% of nominal.
Enable Input. A logic level control of the output. The EN pin is CMOS-compatible. Logic high =
enable, logic low = shutdown. In the off state, supply current of the device is greatly reduced
(typically 5µA). The EN pin should not be left floating.
Power Supply Voltage Input. Requires bypass capacitor to SGND.
5V Internal Linear Regulator Output. VDD supply is the power MOSFET gate drive supply voltage
and the supply bus for the IC. VDD is created by internal LDO from VIN. When VIN < +5.5V, VDD
should be tied to PVIN pins. A 1µF ceramic capacitor from the VDD pin to SGND pins must be place
next to the IC.
December 2012
3
M9999-120712-A