MIC2169A_09 Datasheet, PDF (1/15 Pages) Micrel Semiconductor – 500kHz PWM Synchronous Buck Control IC

MIC2169A
Micrel
MIC2169A
500kHz PWM Synchronous Buck Control IC
General Description
The MIC2169A is a high-efficiency, simple to use 500kHz
PWM synchronous buck control IC housed in a small MSOP-
10 package. The MIC2169A allows compact DC/DC solutions
with a minimal external component count and cost.
The MIC2169A operates from a 3V to 14.5V input, without
the need of any additional bias voltage. The output voltage
can be precisely regulated down to 0.8V. The adaptive all
N‑Channel MOSFET drive scheme allows efficiencies over
95% across a wide load range.
The MIC2169A senses current across the high-side N-
Channel MOSFET, eliminating the need for an expensive
and lossy current-sense resistor. Current limit accuracy is
maintained by a positive temperature coefficient that tracks
the increasing R_DS(ON) of the external MOSFET. Further cost
and space are saved by the internal in-rush-current limiting
digital soft-start.
The MIC2169A is available in a 10-pin MSOP package, with
a wide junction operating range of –40°C to +125°C.
All support documentation can be found on Micrel’s web site
at www.micrel.com.
Features
• 3V to 14.5V input voltage range
• Adjustable output voltage down to 0.8V
• Up to 95% efficiency
• 500kHz PWM operation
• Adjustable current limit senses high-side N-Channel
MOSFET current
• No external current-sense resistor
• Adaptive gate drive increases efficiency
• Overvoltage protection protects the load in fault
conditions
• Dual mode current limit speeds up recovery time
• Hiccup mode short-circuit protection
• Internal soft-start
• Dual function COMP and EN pin allows low-power shut-
down
• Small size MSOP 10-lead package
Applications
• Point-of-load DC/DC conversion
• Set-top boxes
• Graphic cards
• LCD power supplies
• Telecom power supplies
• Networking power supplies
• Cable modems and routers
Typical Application
V_IN = 5V
100F
5
150pF
100nF
4k
0.1µF
SD103BWS
4.7F
0.1F
0.1F
VDD
BST
CS
VIN
HSD
MIC2169A
VSW
2
COMP/EN
LSD
GND ^FB
1k
IRF7821
2.5H
IRF7821
1.4
1000pF
3.3V
10k
3.24k
150F x 2
MIC2169A Adjustable Output 500kHz Converter
100
95
90
85
80
75
70
65
60
55
50
0
MIC2169A Efficiency
V_IN = 5V
V_OUT = 3.3V
2 4 6 8 10 12 14 16
I_LOAD (A)
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com
April 2009
1
M9999-040609