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Features
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MCP1601
Description
The MCP1601 is a fully integrated synchronous BUCK
(step down) DC/DC converter for battery powered sys-
tems. With an input operating range of 2.7V to 5.5V, the
MCP1601 is ideal for applications being powered by
one single cell Li-Ion, 2 to 3 cell NiMH, NiCd or alkaline
sources. Output voltages can range from 0.9V to V
IN
to
accommodate a wide range of applications. Efficiency
can exceed 92% while operating at 750 kHz with load
current capability up to 500 mA. The MCP1601 is used
to minimize space, cost and wasted energy.
The PWM mode switching frequency is internally set to
a fixed 750 kHz allowing the use of low profile, surface
mount inductors and ceramic capacitors while
maintaining a typical efficiency of 92%.
The MCP1601 is capable of three distinct operating
modes: PWM, PFM and Low Drop Out.
When operating in PWM (pulse width modulation)
mode, the DC/DC converter switches at a single high
frequency determined by either the internal 750 kHz
oscillator or external synchronization frequency.
For applications that operate at very light to no load for
extended periods of time, the MCP1601 is capable of
operating in PFM (pulse frequency modulation mode)
to reduce the number of switching cycles/sec and
consume less energy.
The third mode of operation (LDO mode) occurs when
the input voltage approaches the output voltage and the
BUCK duty cycle approaches 100%. The MCP1601 will
enter a low drop out mode and the high-side P-Channel
BUCK switch will saturate, providing the output with the
maximum voltage possible.
The MCP1601 has integrated over-current protection,
over-temperature protection and UVLO (Under Voltage
Lockout) to provide for a fail safe solution with no
external components.
The MCP1601 is available in the 8-pin MSOP package,
with an operating temperature range of -40°C to +85°C.
500 mA Synchronous BUCK Regulator
Input Range of 2.7V to 5.5V
3 Operating Modes: PWM, PFM and LDO
Integrated BUCK and Synchronous Switches
Ceramic or Electrolytic Input/Output Filtering
Capacitors
750 kHz Fixed Switching Frequency
Oscillator Synchronization to 1 MHz PWM Mode
Auto-Switching from PWM/PFM Operation
100% Duty Cycle Capable for Low Input Voltage
500 mA Continuous Output Current Capability
Integrated Under-Voltage Lock-Out Protection
Integrated Over-Temperature Protection
Integrated Soft Start Circuitry
Low Output Voltage Capability to 0.9V
Temperature Range: -40°C to +85ºC
Small 8-Pin MSOP Package
Applications
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Low Power Handheld CPUs and DSPs
Cellular Phones
Organizers and PDAs
Digital Cameras
+5V or +3.3V Distributed Voltages
USB Powered Devices
Package Type
8-Pin MSOP
V
IN
SHDN
FB
A
GND
1
2
3
4
8
L
X
P
GND
V
OUT
SYNC/PWM
MCP1601
7
6
5
2003 Microchip Technology Inc.
DS21762A-page 1
MCP1601
Typical Application
Typical Application (2.7V to 4.2V)
L Range
10 µH to 22 µH
10 µH
V
OUT
Range
1.2V to 3.3V
I
OUT
= 0 mA to 400 mA
C
OUT
10 µF
C
OUT
Range
10 µF to 47 µF
C
1
47 pF
R
1
250 k
Ω
(for 1.8V)
MCP1601
1 V
IN
2 SHDN
Input
Voltage
2.7V-4.2V
C
IN
10 µF
3 FB
4 A
GND
L
X
8
P
GND
7
V
OUT
6
SYNC/ 5
PWM
R
2
200 k
Ω
Functional Block Diagram
V
IN
UVLO
SHDN
Internal
Circuit
Enable
Duty
Clamp
Cycle
Enable Out
Internal
Band Gap
Reference
Buffered 0.8V Output
V
OUT
10 pF
FB
3 M
Ω
0.8V
800 k
Ω
12 pF
R
COMP
C
COMP
-
EA
+
A
GND
+
V
REF
Soft Start
Duty
Cycle
Clamp
10% - 90%
PWM Latch
R
-
I
SENSE
P
+
-
Feedforward Oscillator
K*V
IN
SQW
S
OUT
Inset
Timing
L
X
I
SENSE
P
V
REF
-
I
SENSE
N
PFM Mode
Timing
P
GND
P
GND
PFM Comparator
+
V
REF
I
SENSE
N
A
GND
A
GND
V
REF
-
-
SYNC/PWM
DS21762A-page 2
2003 Microchip Technology Inc.
MCP1601
1.0
ELECTRICAL
CHARACTERISTICS
PIN FUNCTION TABLE
NAME
V
IN
SHDN
FB
A
GND
V
OUT
SYNC/PWM
P
GND
L
X
FUNCTION
Input Source Voltage
Device Shutdown Pin
Output Voltage Feedback Input
Analog Ground
Sensed Output Voltage
Synchronous Clock input or PWM/
PFM select
Power Ground
Output Inductor Node
Absolute Maximum Ratings †
V
IN
- A
GND
......................................................................6.0V
SHDN, FB, SYNC/PWM, V
OUT
..... (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
..................................................≥
4 kV
† Notice:
Stresses above those listed under “Maximum rat-
ings” 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. Expo-
sure to maximum rating conditions for extended periods may
affect device reliability.
ELECTRICAL SPECIFICATIONS
Electrical Specifications:
Unless otherwise indicated, V
IN
=4.2V, V
OUT
=1.8V, I
LOAD
= 10 mA, T
A
=-40°C to +85°C.
Parameters
Power Input Requirements
Voltage
Shutdown Current
PFM Mode Current
Oscillator Section
Internal Oscillator Frequency
External Oscillator Capture Range
External Oscillator Duty Cycle
Internal Power Switches
R
DSon
P-CHANNEL
R
DSon
N-CHANNEL
Dropout Voltage
Pin Leakage Current
Output PWM Mode
Peak Current Limit
Output Voltage
Output Voltage Range
Reference Feedback Voltage
Feedback Input Bias Current
Line Regulation
Load Regulation
Start-Up Time
V
OUT
V
FB
I
VFB
V
LINE-REG
V
LOAD-REG
T
START
0.9
0.78
—
—
—
—
—
0.8
0.1
0.1
1.5
0.5
V
IN
0.82
—
—
—
—
V
V
nA
%/V
%
ms
V
IN
=2.7V to 5.5V, I
LOAD
=10 mA
V
IN
= 3.6V,
I
LOAD
= 0 mA to 300 mA
PWM Mode, SYNC/PWM=V
IN
I
PEAK-PWM
—
1.0
—
A
PWM Mode, SYNC/PWM = V
IN,
T
A
=
+25°C
R
DSon-P
R
DSon-N
V
DROPOUT
I
LX
—
—
—
-1.0
500
500
250
—
—
—
—
1.0
m
Ω
m
Ω
mV
µA
I
P
=100 mA, T
A
=+25°C, V
IN
=4.2V
I
N
=100 mA, T
A
=+25°C, V
IN
=4.2V
V
OUT
= 2.7V, I
LOAD
= 300 mA,
T
A
=+25°C, V
DROPOUT
=97%V
OUT
SHDN = 0V, V
IN
= 5.5V, L
X
= 0V, L
X
=
5.5V
F
OSC
F
SYNC
F
SYN-FALL
650
850
10
750
—
—
850
1000
90
kHz
kHz
%
SYNC/PWM = V
IN
F
SYNC
> F
OSC
F
SYNC
= 1 MHz
V
IN
I(V
IN
)
I(V
IN
)
2.7
—
—
—
0.05
119
5.5
1.0
180
V
µA
µA
I
LOAD
= 0 mA to 500 mA
Shutdown Mode (SHDN = GND)
SYNC/PWM = GND, PFM Mode
(I
LOAD
= 0 mA)
Sym
Min
Typ
Max
Units
Conditions
2003 Microchip Technology Inc.
DS21762A-page 3
MCP1601
ELECTRICAL SPECIFICATIONS
(CONTINUED)
Electrical Specifications:
Unless otherwise indicated, V
IN
=4.2V, V
OUT
=1.8V, I
LOAD
= 10 mA, T
A
=-40°C to +85°C.
Parameters
Protection Features
Average Short Circuit Current
Under-Voltage Lockout
Under-Voltage Lockout Hysteresis
Thermal Shutdown
Thermal Shutdown Hysteresis
Interface Signals (SHDN, SYNC/PWM)
Logic Low Input
Logic High Input
Input Leakage Current
V
IN-HIGH
V
IN-HIGH
I
IN-LK
—
45
—
—
—
—
15
—
0.1
% of
V
IN
% of
V
IN
µA
UVLO
UVLO-
HYS
T
SHD
T
SHD-HYS
—
2.4
—
—
—
890
—
190
160
10
—
2.7
—
—
—
mA
V
mV
°C
°C
R
LOAD
< 1 ohm
For V
IN
decreasing
Sym
Min
Typ
Max
Units
Conditions
TEMPERATURE SPECIFICATIONS
Electrical Specifications:
Unless otherwise noted, all parameters apply at V
DD
= 2.7V to 5.5V
Parameters
Temperature Ranges
Specified Temperature Range
Operating Junction Temperature Range
Storage Temperature Range
Thermal Package Resistances
Thermal Resistance, 8 Pin MSOP
θ
JA
Symbol
Min
Typ
Max
Units
Conditions
T
A
T
J
T
A
-40
-40
-65
—
—
—
—
208
+85
+125
+150
—
°C
°C
°C
°C/W
Single-Layer SEMI G42-88
Board, Natural Convection
DS21762A-page 4
2003 Microchip Technology Inc.
MCP1601
2.0
Note:
TYPICAL PERFORMANCE CURVES
The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.
Note:
Unless otherwise indicated, V
IN
= 4.2V, V
OUT
= 1.8V, L = 10 µH, C
OUT
= 10 µF (X5R Ceramic), C
IN
= 10 µF (X5R
Ceramic), SYNC/PWM=V
IN
.
PFM Mode Quiescent Current
(µA)
100
90
Efficiency (%)
80
70
60
50
40
0
100
200
300
400
500
Load Current (mA)
V
IN
= 4.2V
V
IN
= 3.6V
V
IN
= 2.7V
V
OUT
= 1.2V
Auto PWM/PFM
130
V
OUT
= 1.8V
PFM Mode
I
LOAD
= 0
T
A
= + 25°C
T
A
= + 85°C
120
110
T
A
= + 0°C
T
A
= - 40°C
100
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
FIGURE 2-1:
(V
OUT
= 1.2V).
110
100
Efficiency (%)
90
80
V
IN
= 4.2V
Efficiency vs. Load Current
FIGURE 2-4:
PFM Mode Quiescent
Current vs. Input Voltage.
Internal Oscillator Frequency
(kHz)
780.0
760.0
T
A
= - 40°C
V
OUT
= 1.8V
Auto PWM/PFM
I
LOAD
= 10 mA
Forced PWM Mode
T
A
= 0°C
740.0
720.0
700.0
680.0
2.7
3.1
3.5
3.9
4.3
T
A
= + 125°C
V
IN
= 3.6V
V
IN
= 2.7V
70
60
50
0
100
200
T
A
= + 25°C
300
400
500
4.7
5.1
5.5
Load Current (mA)
Input Voltage (V)
FIGURE 2-2:
(V
OUT
= 1.8V).
110
100
Efficiency (%)
90
V
IN
= 4.5V
Efficiency vs. Load Current
FIGURE 2-5:
Input Voltage.
1.300
1.275
Output Voltage (V)
1.250
1.225
1.200
1.175
1.150
1.125
1.100
Oscillator Frequency vs.
V
OUT
= 3.3V
Auto PWM/PFM
V
OUT
= 1.2V
Auto PWM/PFM
V
IN
= 5.0V
V
IN
= 3.6V
V
IN
= 2.7V
80
70
60
50
0
V
IN
= 5.5V
V
IN
= 4.2V
100
200
300
400
500
0
100
200
300
400
500
Load Current (mA)
Load Current (mA)
FIGURE 2-3:
(V
OUT
= 3.3V).
Efficiency vs. Load Current
FIGURE 2-6:
Current.
Output Voltage vs. Load
2003 Microchip Technology Inc.
DS21762A-page 5
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