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BUCK CONTROLLER. MIC2169 Datasheet |
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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 RDS(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
VIN = 5V
100μF
SD103BWS
4.7μF
0.1μF
VDD
BST
CS
1kΩ
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
VIN = 5V
VOUT = 3.3V
2 4 6 8 10 12 14 16
ILOAD (A)
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
March 2009 1 M9999-032409
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MIC2169
Ordering Information
Part Number
Pb-Free Part Number
MIC2169BMM
MIC2169YMM
Frequency
500kHz
Micrel
Junction Temp. Range
–40°C to +125°C
Package
10-lead MSOP
Pin Configuration
VIN 1
VDD 2
CS 3
COMP 4
FB 5
10 BST
9 HSD
8 VSW
7 LSD
6 GND
10-Pin MSOP (MM)
Pin Description
Pin Number
1
2
3
4
5
6
7
8
9
10
Pin Name
VIN
VDD
CS
COMP
FB
GND
LSD
VSW
HSD
BST
Pin Function
Supply Voltage (Input): 3V to 14.5V.
5V Internal Linear Regulator (Output): VDD is the external MOSFET gate
drive supply voltage and an internal supply bus for the IC. When VIN is <5V,
this regulator operates in dropout mode.
Current Sense (Input): Current-limit comparator noninverting input. The cur-
rent limit is sensed across the MOSFET during the ON time. The current can
be set by the resistor in series with the CS pin.
Compensation (Input): Pin for external compensation. .
Feedback (Input): Input to error amplifier. Regulates error amplifier to 0.8V.
Ground (Return).
Low-Side Drive (Output): High-current driver output for external synchro-
nous MOSFET.
Switch (Return): High-side MOSFET driver return.
High-Side Drive (Output): High-current output-driver for the high-side MOS-
FET. When VIN is between 3.0V to 5V, 2.5V threshold MOSFETs should be
used. At VIN > 5V, 5V threshold MOSFETs should be used.
Boost (Input): Provides the drive voltage for the high-side MOSFET driver.
The gate-drive voltage is higher than the source voltage by VIN minus a
diode drop.
M9999-032409 2 March 2009
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