MIC2169A
Micrel
MIC2169A
500kHz PWM Synchronous Buck Control IC
General Description
The MIC2169A is a high-efficiency, simple to use 500kHz
PWM synchronous buck control IC housed in a small MSOP-
10 package. The MIC2169A allows compact DC/DC solutions
with a minimal external component count and cost.
The MIC2169A 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 MIC2169A 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 MIC2169A 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
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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
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
Point-of-load DC/DC conversion
Set-top boxes
Graphic cards
LCD power supplies
Telecom power supplies
Networking power supplies
Cable modems and routers
Applications
Typical Application
V
IN
= 5V
100F
4.7F
5
VDD
VIN
BST
CS
1k
IRF7821
2
IRF7821
2.5H
1.4
1000pF
10k
150F x 2
3.24k
3.3V
SD103BWS
0.1F
EFFICIENCY (%)
0.1F
100
95
90
85
80
75
70
65
60
55
50
MIC2169A Efficiency
HSD
MIC2169A
VSW
LSD
FB
150pF
100nF
4k
COMP/EN
0.1µF
GND
V
IN
= 5V
V
OUT
= 3.3V
0
2
4
6 8 10 12 14 16
I
LOAD
(A)
MIC2169A Adjustable Output 500kHz 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 2009
1
M9999-040609
MIC2169A
Micrel
Pb-Free Part Number
MIC2169AYMM
Frequency
500kHz
Junction Temp. Range
–40°C to +125°C
Package
10-lead MSOP
Ordering Information
Part Number
MIC2169ABMM
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)
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,
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 MOS-
FET. When V
IN
is between 3.0V to 5V, 2.5V threshold MOSFETs should be
used. At V
IN
> 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 V
IN
minus a
diode drop.
3
CS
4
COMP/EN
5
6
7
8
9
FB
GND
LSD
VSW
HSD
10
BST
M9999-040609
2
April 2009
MIC2169A
Micrel
Absolute Maximum Ratings
(1)
Supply Voltage (V
IN
) ................................................... 15.5V
Booststrapped Voltage (V
BST
) .................................V
IN
+5V
Junction Temperature (T
J
) ..................–40°C ≤ T
J
≤ +125°C
Storage Temperature (T
S
) ........................ –65°C to +150°C
Operating Ratings
(2)
Supply Voltage (V
IN
) ..................................... +3V to +14.5V
Output Voltage Range .......................... 0.8V to V
IN
×
D
MAX
Package Thermal Resistance
θ
JA
10-lead MSOP ............................................. 180°C/W
Electrical Characteristics
(3)
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
(4)
Input and V
DD
Supply
PWM Mode Supply Current
Shutdown Quiescent Current
V
COMP
Shutdown Blanking
Period
V
COMP
Shutdown Threshold
V
CS
= V
IN
–0.25V; V
FB
= 0.7V (output switching but excluding
external MOSFET gate current.)
V
COMP/EN
= 0V
C
COMP
= 100nF
V
IN
≥ 6V
4.7
0.1
1.5
50
0.25
4
5
5.3
3
150
0.4
mA
µA
V
ms
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
30
0.03
0.5
0.6
Max
0.808
0.816
100
Units
V
V
nA
%/V
%
%
Digital Supply Voltage (V
DD
)
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, 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 2009
3
M9999-040609
MIC2169A
Micrel
Electrical Characteristics
(5)
Parameter
Error Amplifier
DC Gain
Transconductance
Soft-Start
Soft-Start Current
Current Sense
CS Over Current Trip Point
Temperature Coefficient
ppm/°C
Output Fault Correction Thresholds
Lower Threshold, V
FB_UVT
Gate Drivers
Rise/Fall Time
Output Driver Impedance
Into 3000pF at V
IN
> 5V
Source, V
IN
= 5V
Sink, V
IN
= 5V
Source, V
IN
= 3V
Sink, V
IN
= 3V
Driver Non-Overlap Time
Notes:
5. Specification for packaged product only.
6. Guaranteed by design.
Condition
Min
Typ
70
1
Max
Units
dB
ms
µA
After timeout of internal timer. See
“Soft-Start”
section.
V
CS
= V
IN
–0.25V
160
8.5
200
+1800
240
µA
Upper Threshold, V
FB_OVT
(relative to V
FB
)
(relative to V
FB
)
+3
–3
30
6
6
10
10
10
20
%
%
ns
Ω
Ω
Ω
Ω
ns
Note 6
M9999-040609
4
April 2009
MIC2169A
Micrel
Typical Characteristics
V
IN
= 5V
2.9
2.7
2.5
2.3
2.1
1.9
1.7
1.5
1.3
1.1
0.9
0.7
0.5
-40 -20 0 20 40 60 80 100120140
TEMPERATURE (C)
PWM Mode Supply Current
vs. Temperature
2.0
QUIESCENT CURRENT (mA)
PWM Mode Supply Current
vs. Supply Voltage
0.8010
0.8005
V
FB
Line Regulation
I
DD
(mA)
V
FB
(V)
1.5
0.8000
0.7995
0.7990
0.7985
1.0
0.5
0.7980
0
5
10
SUPPLY VOLTAGE (V)
15
0
5
V
IN
(V)
10
15
0.804
0.802
V
DD
(V)
V
DD
REGULATOR VOLTAGE (V)
0.806
V
FB
vs. Temperature
6
5
4
3
2
1
0
0
V
DD
Line Regulation
5.02
5.00
4.98
4.96
4.94
4.92
4.90
0
V
DD
Load Regulation
V
FB
(V)
0.800
0.798
0.796
0.794
0.792
-60 -30 0 30 60 90 120 150
TEMPERATURE (C)
5
V
IN
(V)
10
15
5
10 15 20 25
LOAD CURRENT (mA)
30
V
DD
LINE REGULATION (%)
FREQUENCY (kHz)
540
530
520
510
500
490
480
470
460
450
-60 -30 0 30 60 90 120 150
TEMPERATURE (C)
FREQUENCY VARIATION (%)
5.0
4.5
4.0
3.5
V
DD
Line Regulation
vs. Temperature
550
Oscillator Frequency
vs. Temperature
1.5
1.0
0.5
0
-0.5
-1.0
-1.5
0
Oscillator Frequency
vs. Supply Voltage
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-60 -30 0 30 60 90 120 150
TEMPERATURE (C)
5
V
IN
(V)
10
15
4
3
V
OUT
(V)
Current Limit Foldback
260
240
220
I
CS
(
A)
200
180
160
140
120
Overcurrent Trip Point
vs. Temperature
2
1
0
Top MOSFET = Si4800
R
CS
= 1k
0
2
4
6
I
LOAD
(A)
8
10
100
-60 -30 0 30 60 90 120 150
TEMPERATURE (C)
April 2009
5
M9999-040609
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