MIC2174_10 Datasheet, PDF (2/27 Pages) Micrel Semiconductor – Synchronous Buck Controller Featuring Adaptive On-Time Control 40V Input, 300kHz

Micrel, Inc.
MIC2174/MIC2174C
Ordering Information
Part Number
MIC2174-1YMM
MIC2174C-1YMM
Voltage
Adj.
Adj.
Accuracy
±1%
±3%
Switching Frequency
300kHz
270kHz
Junction Temperature
Range
–40° to +125°C
–40° to +125°C
Package Lead Finish
10-Pin MSOP
10-Pin MSOP
Pb-Free
Pb-Free
Pin Configuration
10-Pin MSOP (MM)
Pin Description
Pin Number
1
2
3
4
5
6
7
8
Pin Name
HSD
EN
FB
GND
IN
DL
PGND
DH
Pin Function
High-Side N-MOSFET Drain Connection (input): Power to the drain of the external high-side N-
channel MOSFET. The HSD operating voltage range is from 3V to 40V. Input capacitors between
HSD and the power ground (PGND) are required.
Enable (input): A logic level control of the output. The EN pin is CMOS-compatible. Logic high or
floating = enable, logic low = shutdown. In the off state, supply current of the device is greatly reduced
(typically 0.8mA).
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.
Signal ground. GND is the ground path for the device input voltage V_IN and the control circuitry. The
loop for the signal ground should be separate from the power ground (PGND) loop.
Input Voltage (input): Power to the internal reference and control sections of the MIC2174/MIC2174C.
The IN operating voltage range is from 3V to 5.5V. A 2.2µF ceramic capacitors from IN to GND are
recommended for clean operation. V_IN must be powered up no earlier than V_HSD to make the soft-start
function behavior correctly.
Low-Side Drive (output): High-current driver output for external low-side MOSFET. The DL driving
voltage swings from ground to IN.
Power Ground. PGND is the ground path for the MIC2174/MIC2174C buck converter power stage.
The PGND pin connects to the sources of low-side N-Channel 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 (GND) loop.
High-Side Drive (output): High-current driver output for external high-side MOSFET. The DH driving
voltage is floating on the switch node voltage (LX). It swings from ground to V_IN minus the diode drop.
Adding a small resistor between DH pin and the gate of the high-side N-channel MOSFETs can slow
down the turn-on and turn-off time of the MOSFETs.
September 2010
2
M9999-091310-C