MIC2169_09 Datasheet, PDF (1/15 Pages) Micrel Semiconductor – 500kHz PWM Synchronous Buck Control IC

MIC2169
Micrel
MIC2169
500kHz PWM Synchronous Buck Control IC
General Description
The MIC2169 is a high-efficiency, simple to use 500kHz PWM
synchronous buck control IC housed in a small MSOP-10
package. The MIC2169 allows compact DC/DC solutions
with a minimal external component count and cost.
The MIC2169 operates using a 3V to 14.5V input, without
the need for 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 MIC2169 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
via a positive temperature coefficient that tracks the increas-
ing R_DS(ON) of the external MOSFET. Additional cost and
space are saved by the internal in-rush-current limiting and
digital soft-start.
The MIC2169 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
• Fast transient response
– Externally compensated
• Overvoltage protection protects the load in fault
conditions
• Dual mode current limit speeds up recovery time
• Hiccup mode short-circuit protection
• 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
100μF
SD103BWS
4.7μF
0.1μF
VDD
BST
1kΩ
CS
150pF
100nF
VIN
HSD
MIC2169
VSW
COMP/EN
LSD
4kΩ
GND ^FB
IRF7821
2.5μH
IRF7821
3.3V
10kΩ
3.24kΩ
150μF x 2
MIC2169 Adjustable Output 500kHz Converter
100
95
90
85
80
75
70
65
60
55
50
0
MIC2169 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
March 2009
1
M9999-032409