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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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MIC2168
Absolute Maximum Ratings(1)
Supply Voltage (VIN)................................................... 15.5V
Booststrapped Voltage (VBST) .................................VIN +5V
Junction Temperature (TJ) ...................–40°C ≤ TJ ≤+125°C
Storage Temperature (TS) ........................ –65°C to +150°C
Micrel, Inc.
Operating Ratings(2)
Supply Voltage (VIN)..................................... +3V to +14.5V
Output Voltage Range .......................... 0.8V to VIN × DMAX
Package Thermal Resistance
θJA 10-lead MSOP ............................................. 180°C/W
Electrical Characteristics(3)
TJ = 25°C, VIN = 5V, unless otherwise specified. Bold values indicate –40°C < TJ < +125°C
Parameter
Condition
Feedback Voltage Reference
(± 1%)
Feedback Voltage Reference
(± 2% over temp)
Feedback Bias Current
Output Voltage Line Regulation
Output Voltage Load Regulation
Output Voltage Total Regulation
Oscillator Section
3V ≤ VIN ≤ 14.5V; 1A ≤ IOUT ≤ 10A; (VOUT = 2.5V)(4)
Oscillator Frequency
Maximum Duty Cycle
Minimum On-Time(4)
Input and VDD Supply
PWM Mode Supply Current
VCS = VIN –0.25V; VFB = 0.7V (output switching but excluding
external MOSFET gate current.)
Shutdown Quiescent Current
VCOMP Shutdown Threshold
VCOMP Shutdown Blanking
Period
VCOMP/EN = 0V
CCOMP = 100nF
Digital Supply Voltage (VDD)
VIN ≥ 6V
Min Typ Max Units
0.792 0.8 0.808 V
0.784 0.8 0.816 V
30 100 nA
0.03 % / V
0.5 %
0.6 %
900 1000 1100 kHz
90 %
30 60 ns
1.6 3 mA
50 150 µA
0.1 0.25 0.4
V
4 ms
4.7 5 5.3 V
Notes:
1. Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating
the device outside of its operating ratings. The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(max),
the junction-to-ambient thermal resistance, θJA, and the ambient temperature, TA. The maximum allowable power dissipation will result in excessive
die temperature, and the regulator will go into thermal shutdown.
2. Devices are ESD sensitive, handling precautions required.
3. Specification for packaged product only.
4. Guaranteed by design.
April 2005
3 M9999-040805
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