MIC2168A
1MHz PWM Synchronous Buck-Control IC
General Description
The MIC2168A is a high-efficiency, simple to use 1MHz
PWM synchronous buck-control IC housed in a small
MSOP-10 package. The MIC2168A allows compact
DC/DC solutions with a minimal external component
count and cost.
The MIC2168A 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 MIC2168A 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 and digital soft-
start.
The MIC2168A is identical to the MIC2168 with the
exception that the MIC2168A increases the overcurrent
blanking time from 80ns (typ.) to 120ns (typ.)
The MIC2168A 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
Small-size MSOP 10-pin 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
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 •
http://www.micrel.com
January 2010
M9999-011510
Micrel
MIC2168A
Ordering Information
Part Number
Standard
MIC2168ABMM
Pb-Free
MIC2168AYMM
Frequency
1MHz
Junction Temperature Range
(1)
–40° to +125°C
Package
10-Pin MSOP
Pin Configuration
VIN 1
VDD 2
CS 3
COMP/EN 4
FB 5
10 BST
9 HSD
8 VSW
7 LSD
6 GND
MIC2168A 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 current 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 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-rated 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
5
6
7
8
9
COMP
FB
GND
LSD
VSW
HSD
10
BST
January 2010
2
M9999-011510
Micrel
MIC2168A
Absolute Maximum Ratings
(1)
Supply Voltage (V
IN
) ........................................... 15.5V
Bootstrapped 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
10-Pin MSOP (θ
JA
) .................................. 180°C/W
Electrical Characteristics
(3)
T
J
= 25°C, V
IN
= 5V, unless otherwise specified.
Bold
values indicate –40°C < T
J
< +125°C
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)
Condition
(± 1%)
(± 2% over temp)
Min.
0.792
0.784
Typ.
0.8
0.8
30
0.03
0.5
Max.
0.808
0.816
100
Units
V
V
nA
%/V
%
%
3V
≤
V
IN
≤
14.5V; 1A
≤
I
OUT
≤
10A; (V
OUT
= 2.5V)
(4)
0.6
900
90
30
60
3
1000
1100
kHz
ns
mA
Input and V
DD
Supply
PWM Mode Supply Current
V
CS
= V
IN
–0.25V; V
FB
= 0.7V
(output switching but excluding external MOSFET
gate current.)
V
COMP/EN
=0V
0.1
C
COMP
= 100nF
V
IN
≥
6V
4.7
1.6
Shutdown Quiescent Current
VCOMP Shutdown Threshold
VCOMP Shutdown Blanking
Period
Digital Supply Voltage (V
DD
)
Error Amplifier
DC Gain
Transconductance
Soft Start
Soft-Start Current
Current Sense
CS Overcurrent Trip Point
Temperature Coefficient
Notes:
1.
50
0.25
4
5
70
1
150
0.4
µA
V
ms
5.3
V
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
ppm/°C
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.
Devices are ESD sensitive, handling precautions required.
Specification for packaged product only.
Guaranteed by design.
2.
3.
4.
January 2010
3
M9999-011510
Micrel
MIC2168A
Electrical Characteristics
(5)
(continued)
T
J
= 25°C, V
IN
= 5V, unless otherwise specified.
Bold
values indicate –40°C < T
J
< +125°C
Parameter
Upper Threshold, V
FB_OVT
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
(relative to V
FB
)
(relative to V
FB
)
Min.
Typ.
+3
-3
30
Max.
Units
%
%
ns
Output Fault Correction Thresholds
6
6
10
10
10
20
Ω
Ω
Ω
Ω
ns
Note 6
January 2010
4
M9999-011510
Micrel
MIC2168A
Typical Characteristics
January 2010
5
M9999-011510
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