MCP1612
Single 1A 1.4 MHz Synchronous Buck Regulator
Features
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Fixed Switching Frequency: 1.4 MHz
Input Operating Voltage Range: 2.7V to 5.5V
Integrated Buck and Synchronous Switches
Adjustable Output Voltage Range: 0.8V to 5.0V
100% Duty Cycle Capable for Low Input Voltage
Continuous Output Current Capability: 1A
Shutdown Control with I
Q
< 0.01
µ
A (Typical)
Integrated Soft Start
Integrated Undervoltage Lockout (UVLO)
Protection
Integrated Overtemperature Protection
Fast Dynamic Response to Line and Load Steps
Small, 8-Pin DFN and MSOP Packages
Operating Temperature Range: -40°C to +85°C
Description
The MCP1612 is a 1A, 1.4 MHz fully integrated current
mode-controlled synchronous Buck regulator. The
MCP1612 is packed in the 8-pin MSOP and the space-
saving 3 x 3 DFN package. The DFN package also
provides a lower thermal resistance package option for
high-power, high ambient temperature applications.
With an input operating range of 2.7V to 5.5V, the
MCP1612 is ideal for applications that are powered by
one single-cell Li-Ion, 2 to 3 cell NiMH, NiCd or alkaline
sources.
The output voltage of the MCP1612 is easily set over
the range of 0.8V to 5.0V by using an external resistor
divider. The external inductor and output capacitor size
are minimized since an internally-fixed 1.4 MHz clock is
used to set the switching frequency. The fixed clock
allows for continuous, fixed-frequency PWM operation
over the full load range.
The MCP1612 is designed to provide fast dynamic
response to sudden changes in input voltage and load
current to minimize the necessary amount of external
output capacitance.
The MCP1612 can be used with ceramic, tantalum or
aluminum electrolytic output capacitors. Ceramic
capacitors with values as low as 4.7 µF can be used to
keep the output ripple voltage low. For applications that
require better load step performance, the value of the
output capacitor can be increased to 47 µF.
Additional features integrated into the MCP1612
include shutdown capability, soft start, Undervoltage
Lockout, overcurrent and overtemperature protection.
Applications
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Network Interface Cards
Portable Computers
Set Top Boxes
DSL Modems and Routers
USB-Powered Devices
GBIC Modules
High-Speed Data System BUS Termination
Medical Instruments
Cellular/GSM/PHS Phones
+5V or +3.3V Distributed Voltages
Package Types
8-Lead DFN
V
IN
1
V
CC
2
SHDN 3
COMP 4
8 L
X
7 P
GND
6 V
GND
5 FB
8-Lead MSOP
V
IN
1
V
CC
2
SHDN 3
COMP 4
8 L
X
7 P
GND
6 V
GND
5 FB
2004 Microchip Technology Inc.
DS21921A-page 1
MCP1612
Functional Block Diagram
V
CC
Undervoltage
Lockout
(UVLO)
Slope Comp.
+
+
UVLO
V
IN
I
SENSE
P-Channel
Peak Current
Limit
Disable
INSET
CKT.
IN
PDRV
L
X
NDRV
Comp
V
REF
FB
-
gm
+
Soft
Start
Disable
Disable
1.4 MHz Clock
Leading-
Edge
Blank
V
REF
Peak Current
Limit
P
GND
P
GND
V
CC
V
CC
A
1.2V
V
BG
UVLO
Disable
SHDN
A
GND
0.8V
A
GND
A
GND
Thermal
Shutdown
DS21921A-page 2
2004 Microchip Technology Inc.
MCP1612
Typical Application Circuit
MCP1612 3.3V to 1.2V Synchronous Buck Converter
3.3V
IN
±10%
C
IN
10 µF
Ceramic
10Ω
1
V
IN
L
x
8 L = 3.3 µH
1.2V V
OUT
@ 1A
C
OUT
10 µF
Ceramic
100 kΩ
MCP1612
P
GND
A
GND
7
6
2
C
byp
0.1 µF
Ceramic
V
CC
3
ON
OFF
SHDN
200 kΩ
4
Comp
FB
5
25 kΩ
1000 pF
2004 Microchip Technology Inc.
DS21921A-page 3
MCP1612
1.0
ELECTRICAL
CHARACTERISTICS
† Notice:
Stresses above those listed under “Maximum
Ratings” may cause permanent damage to the device. This is
a stress rating only and functional operation of the device at
those or any other conditions above those indicated in the
operational listings of this specification is not implied.
Exposure to maximum rating conditions for extended periods
may affect device reliability.
Absolute Maximum Ratings †
V
IN
– A
GND
.....................................................................6.0V
(SHDN, FB, V
CC
, Comp ........... (A
GND
– 0.3V) to (V
IN
+ 0.3V)
L
X
to P
GND
.............................................. -0.3V to (V
IN
+ 0.3V)
P
GND
to A
GND
................................................... -0.3V to +0.3V
Output Short Circuit Current ................................. Continuous
Storage temperature .....................................-65°C to +150°C
Ambient Temp. with Power Applied.................-40°C to +85°C
Operating Junction Temperature...................-40°C to +125°C
ESD protection on all pins (HBM)
.......................................
4 kV
ESD protection on all pins (MM)........................................ 300 V
DC CHARACTERISTICS
Electrical Specifications:
Unless otherwise noted, V
IN
= V
cc
= V
SHDN
= 3.3V, V
OUT
= 1.8V, C
IN
= C
OUT
= 10 µF, L = 3.3 µH,
I
LOAD
= 100 mA, T
A
= +25°C.
Boldface
specifications apply over the T
A
range of -40°C to +85°C.
Parameters
Input Voltage
Input Operating Voltage
Input Shutdown Current
Input Quiescent Current
Oscillator Characteristics
Internal Oscillator Frequency
Internal Power Swicthes
R
DSon
P-Channel
R
DSon
N-Channel
L
X
Pin Leakage Current
Positive Current Limit Threshold
Negative Current Limit Threshold
Feedback Characteristics
Transconductance from FB to
COMP
Output Voltage
Output Voltage Range
Reference Feedback Voltage
Feedback Input Bias Current
Line Regulation
Load Regulation
Note 1:
V
OUT
V
FB
I
VFB
V
LINE-REG
V
LOAD-REG
0.8
0.78
—
—
—
—
0.8
1
0.15
0.25
V
IN
0.82
—
0.5
—
V
V
nA
%/V
%
V
IN
= 2.7V to 5.5V, I
LOAD
= 100 mA
V
IN
= 4.2V, I
LOAD
= 100 mA to 1A
g
m
35
62
90
µA/V
R
DSon-P
R
DSon-N
I
LX
+I
LX(MAX)
-I
LX(MAX)
—
—
-1
—
—
300
300
—
2.3
-1.4
—
—
1
—
—
mΩ
mΩ
µA
A
A
I
P
= 250 mA
I
N
= 250 mA
SHDN = 0V, V
IN
= 5.5V, L
X
= 0V,
L
X
= 5.5V
F
OSC
1.2
1.4
1.6
MHz
V
IN
I(V
IN
)
I(V
IN
)
2.7
—
—
—
0.01
5
5.5
1
7
V
µA
mA
Shutdown mode (SHDN = GND)
I
LOAD
= 0 mA
Sym
Min
Typ
Max
Units
Conditions
2:
The integrated MOSFET switches have an integral diode from the L
X
pin to V
IN
and from L
X
to P
GND
. In cases where
these diodes are forward-biased, the package power dissipation limits must be adhered to. Thermal protection is not
able to limit the junction temperature for these cases.
UVLO is specified for a falling V
IN
. Once the UVLO is activated, the UVLO-
HYS
must be overcome before the device will
return to operation.
DS21921A-page 4
2004 Microchip Technology Inc.
MCP1612
DC CHARACTERISTICS (CONTINUED)
Electrical Specifications:
Unless otherwise noted, V
IN
= V
cc
= V
SHDN
= 3.3V, V
OUT
= 1.8V, C
IN
= C
OUT
= 10 µF, L = 3.3 µH,
I
LOAD
= 100 mA, T
A
= +25°C.
Boldface
specifications apply over the T
A
range of -40°C to +85°C.
Parameters
Protection Features
Undervoltage Lockout
Undervoltage Lockout Hysteresis
Thermal Shutdown
Thermal Shutdown Hysteresis
Interface Signal (SHDN)
Logic-High Input
Logic-Low Input
Note 1:
V
IN-HIGH
V
IN-LOW
45
—
—
—
—
15
% of V
IN
% of V
IN
UVLO
UVLO-
HYS
T
SHD
T
SHD-HYS
2.4
—
—
—
2.55
200
160
9
2.7
—
—
—
V
mV
°C
°C
Note 1
Note 2
Sym
Min
Typ
Max
Units
Conditions
2:
The integrated MOSFET switches have an integral diode from the L
X
pin to V
IN
and from L
X
to P
GND
. In cases where
these diodes are forward-biased, the package power dissipation limits must be adhered to. Thermal protection is not
able to limit the junction temperature for these cases.
UVLO is specified for a falling V
IN
. Once the UVLO is activated, the UVLO-
HYS
must be overcome before the device will
return to operation.
TEMPERATURE SPECIFICATIONS
Electrical Specifications:
V
IN
= 3.0V to 5.5V, F
OSC
= 1 MHz with 10% Duty Cycle, C
IN
= 0.1 µF. T
A
= -40°C to +125°C.
Parameters
Temperature Ranges
Storage Temperature Range
Maximum Junction Temperature
Operating Junction Temperature Range
Thermal Package Resistances
Thermal Resistance, 8L-MSOP
θ
JA
θ
JA
—
—
208
41
—
—
°C/W
°C/W
Typical 4-layer board interconnecting
vias
Typical 4-layer board interconnecting
vias
T
A
T
J
T
A
-65
—
- 40
—
—
—
+150
+150
+ 125
°C
°C
°C
Continuous
Transient Only
Continuous Operation
Sym
Min
Typ
Max
Units
Conditions
Thermal Resistance, 8L-DFN
2004 Microchip Technology Inc.
DS21921A-page 5
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