MIC2169B
500kHz PWM Synchronous Buck
Control IC
General Description
The MIC2169B is a high-efficiency, simple to use 500kHz
PWM synchronous buck control IC housed in small
MSOP-10 and MSOP-10 ePad packages. The MIC2169B
allows compact DC/DC solutions with a minimal external
component count and cost. The device features high-
output driver capability to drive loads up to 30A.
The MIC2169B 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 within the smallest possible
printed circuit board space area.
The MIC2169B 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 MIC2169B is identical to the
MIC2169A with the exception that the MIC2169B supports
pre-bias loads and has a lower impedance gate-drive
circuit. Internal pre-bias circuit prevents output voltage
drooping and excessive reverse inductor current when
powering up with a pre-bias voltage at the output.
The MIC2169B is available in a 10-pin MSOP and a
thermally-capable 10-pin ePad 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
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3V to 14.5V input voltage range
Adjustable output voltage down to 0.8V
500kHz PWM operation
Up to 95% efficiency
Output Pre-biased Protection
Build-in 2.2Ω drivers to drive two n-channel MOSFETs
Adaptive gate drive increases efficiency
Simple, externally-compensated voltage-mode PWM
control
Short minimum ON time of 30ns allowing very-low duty
cycle
Fast transient response
Adjustable current limit senses high-side N-Channel
MOSFET current
Hiccup mode short-circuit protection
No external current-sense resistor
Internal soft-start current source
Dual function COMP and EN pin allows low-power
shutdown
Available in small-size 10-pin MSOP and 10-pin MSOP
ePad packages
Point-of-load DC/DC conversion
High-Current Power Supplies
Telecom/Datacom and Networking Power Supplies
Servers and Workstations
Graphic cards and other PC Peripherals
Set-top boxes
LCD power supplies
Applications
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___________________________________________________________________________________________________________
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 2010
M9999-041210-B
Micrel, Inc.
MIC2169B
Typical Application
V
IN
= 5V to 12V
100µF
10µF
SD103BWS
10µF
0.1µF
0.1µF
EFFICIENCY (%)
100
95
90
85
80
75
70
65
60
55
50
MIC2169B Efficienc
VDD
BST
CS
HSD
IRF7821
1.0µH
IRF7821
1000pF
330µF x 2
3.3V
VIN
MIC2169B
VSW
COMP/EN
150pF
100nF
1µF
GND
EP
LSD
FB
V
IN
= 5V
V
OUT
= 3.3V
0
2
4
6 8 10 12 14 16
I
LOAD
(A)
MIC2169B Adjustable Output 500kHz Converter
April 2010
2
M9999-041210-B
Micrel, Inc.
MIC2169B
Ordering Information
Part Number
MIC2169BYMME
MIC2169BYMM
Frequency
500kHz
500kHz
Junction Temperature Range
(1)
-40° to +125°C
-40° to +125°C
Package
10-Lead ePad MSOP
10-Lead MSOP
Lead Finish
Pb-Free
Pb-Free
Pin Configuration
10-Pin ePad MSOP (MME)
10-Pin MSOP
Pin Description
Pin Number
1
2
Pin Name
VIN
VDD
Pin Function
Supply Voltage (Input): +3V to +14.5V.
5V Internal Linear Regulator (Output): V
DD
is the external MOSFET gate-drive
supply voltage and an internal supply bus for the IC. When V
IN
is <5V, short
VDD to the input supply through a 10Ω resistor.
Current Sense (Input): Current-limit comparator noninverting input. The current
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 / Enable (Input): Dual function pin. Pin for external compensation.
If this pin is pulled below 0.25V, 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 synchronous
MOSFET.
Switch (Return): High-side MOSFET driver return.
High-Side Drive (Output): High-current output-driver for the high-side MOSFET.
When V
IN
is between 3.0V to 5V, 2.5V threshold MOSFETs should be used. At
V
IN
> 5V, 4.5V 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 V
DD
minus a diode drop.
Connect to Ground.
3
CS
4
COMP/EN
5
6
7
8
9
FB
GND
LSD
VSW
HSD
10
ePad
BST
EP
April 2010
3
M9999-041210-B
Micrel, Inc.
MIC2169B
Absolute Maximum Ratings
(1)
Supply Voltage (V
IN
) ...................................... -0.3V to 15.5V
Booststrapped Voltage (V
BST
) .................... -0.3V to V
IN
+6V
VSW .............................................................. -0.3V to 15.5V
CS ............................................................................15.25V
LSD,FB............................................................... -0.3V to 6V
Storage Temperature (T
S
)..........................-65°C to +150°C
Peak Reflow Temperature (10 to 20 sec) ................ +260°C
ESD (HBM)
(3)
................................................................. 2kV
ESD (MM).....................................................................200V
Operating Ratings
(2)
Supply Voltage (V
IN
)...................................... +3V to +14.5V
Ambient Temperature (T
A
) ...........................-40°C to +85°C
Junction Temperature (T
J
) ..........................-40°C to+125°C
Junction Thermal Resistance
ePad MSOP (θ
JA
)............................................76.7°C/W
ePad MSOP (θ
JC
) .............................................9.6°C/W
MSOP (θ
JA
) ......................................................130°C/W
MSOP (θ
JC
).....................................................42.6°C/W
Output Voltage Range............................. 0.8V to V
IN
× D
MAX
Electrical Characteristics
(4)
T
J
= 25°C, V
IN
= 5V;
Bold
values indicate –40°C
≤
T
J
≤
+125°C; unless otherwise specified.
Parameter
Feedback Voltage Reference
Feedback Voltage Reference
Feedback Bias Current
Output Voltage Line
Regulation
Output Voltage Load
Regulation
Output Voltage Total
Regulation
Oscillator Section
Oscillator Frequency
Maximum Duty Cycle
Minimum On-Time
(5)
Input and V
DD
Supply
PWM Mode Supply Current
Shutdown Quiescent Current
V
COMP
Shutdown Threshold
V
COMP
Shutdown Blanking
Period
Digital Supply Voltage (V
DD
)
C
COMP
= 100nF
V
IN
≥
6V
4.7
V
CS
= V
IN
–0.25V; V
FB
= 0.7V (output switching but
excluding external MOSFET gate current.)
V
COMP
/EN = 0V
0.1
1.5
50
0.25
675
5
5.3
3
150
0.35
mA
µA
V
μs
V
450
92
30
60
500
550
kHz
%
ns
3V
≤
V
IN
≤
14.5V; 1A
≤
I
OUT
≤
10A; (V
OUT
= 2.5V)
(4)
Condition
(±1%)
(±2% over temp)
Min
0.792
0.784
Typ
0.8
0.8
150
0.03
0.5
0.6
1.5
Max
0.808
0.816
350
Units
V
V
nA
%/V
%
%
April 2010
4
M9999-041210-B
Micrel, Inc.
MIC2169B
Electrical Characteristics
(4)
(continued)
T
J
= 25°C, V
IN
= 5V;
Bold
values indicate –40°C
≤
T
J
≤
+125°C; unless otherwise specified.
Parameter
Error Amplifier
DC Gain
(5)
Transconductance
Soft-Start
Soft-Start Current
Current Sense
CS Over Current Trip Point
Temperature Coefficient
Gate Drivers
Rise/Fall Time
Output Driver Impedance
Into 3000pF at V
IN
> 5V
Source, V
IN
= 4.5V
Sink, V
IN
= 4.5V
Source, V
IN
= 3V
Sink, V
IN
= 3V
Driver Non-Overlap Time
(5)
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, T
J
(max),
the junction-to-ambient thermal resistance,
θ
JA
, and the ambient temperature, T
A
. The maximum allowable power dissipation will result in excessive
die temperature.
2. The device is not guaranteed to function outside its operating rating.
3. Devices are ESD sensitive, handling precautions required.
4. Specification for packaged product only.
5.
Guaranteed by design.
Condition
Min
Typ
70
1.1
Max
Units
dB
mΩ
–1
After time out of internal timer. V
COMP
= 0.8V
V
CS
= V
IN
–0.25V
4
160
8.5
200
1800
15
2.2
1.3
2.7
1.7
13
240
µA
µA
ppm/°C
ns
3
3
4
4
Ω
Ω
Ω
Ω
ns
50
April 2010
5
M9999-041210-B
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