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CONTROL IC. MIC2168 Datasheet |
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MIC2168
Micrel, Inc.
MIC2168
1MHz PWM Synchronous Buck Control IC
General Description
The MIC2168 is a high-efficiency, simple to use 1MHz PWM
synchronous buck control IC housed in a small MSOP-10
package. The MIC2168 allows compact DC/DC solutions
with a minimal external component count and cost.
The MIC2168 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 MIC2168 senses current across the high-side N-Chan-
nel MOSFET, eliminating the need for an expensive and
lossy current-sense resistor. Current limit accuracy is main-
tained by a positive temperature coefficient that tracks the
increasing RDS(ON) of the external MOSFET. Further cost
and space are saved by the internal in-rush-current limiting
digital soft-start.
The MIC2168 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
• 1MHz PWM operation
• Adjustable current-limit senses high-side N-Channel
MOSFET current
• No external current sense resistor
• Adaptive gate drive increases efficiency
• Ultra-fast response with hysteretic transient recovery
mode
• 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
VIN = 5V
100µF
SD103BWS
4.7µF
0.1µF
VDD
BST
CS
1kΩ
100pF
100nF
VIN HSD
MIC2168
VSW
COMP/EN
LSD
4kΩ GND FB
IRF7821
1.2µH
IRF7821
3.3V
10kΩ
3.24kΩ
150µF x 2
MIC2168 Adjustable Output 1MHz Converter
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
April 2005
1 M9999-040805
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MIC2168
Ordering Information
Part Number
Standard
Pb-Free
MIC2168BMM MIC2168YMM
Frequency Junction Temp. Range
Package
1MHz
-40°C to +125°C
10-Lead MSOP
Pin Configuration
VIN 1
VDD 2
CS 3
COMP/EN 4
FB 5
10 BST
9 HSD
8 VSW
7 LSD
6 GND
10-Pin MSOP (MM)
Micrel, Inc.
Pin Description
Pin Number
1
2
3
4
5
6
7
8
9
10
Pin Name
VIN
VDD
CS
COMP/EN
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 / Enable (Input): Current-limit comparator noninverting input.
The current limit is sensed across the MOSFET during the ON time. The cur-
rent can be set by the resistor in series with the CS pin.
Compensation (Input): Dual function pin. Pin for external compensation.
If this pin is pulled below 0.2V, with the reference fully up the device shuts
down (50µA typical current draw).
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
MOSFET. When VIN is between 3.0V to 5V, 2.5V threshold-rated 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.
M9999-040805
2
April 2005
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