MCP1612
Single 1A, 1.4 MHz Synchronous Buck Regulator
Features
Description
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The MCP1612 is a 1A, 1.4 MHz, fully-integrated,
current mode-controlled, synchronous buck regulator.
The MCP1612 is packaged in the 8-pin MSOP and
space-saving, 3x3 DFN packages. The DFN package
also provides a lower thermal resistance package
option for high-power, high ambient temperature
applications. With an input operating range from 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.
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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 IQ < 0.01 µA (Typ.)
Integrated Soft-Start Feature
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
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
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 due to an internally-fixed, 1.4 MHz clock
being 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, UVLO,
overcurrent and overtemperature protection.
Package Types
8-Lead DFN
VIN 1
VCC 2
2004-2013 Microchip Technology Inc.
8 LX
8-Lead MSOP
VIN 1
8 LX
7 PGND
VCC 2
SHDN 3
6 AGND
SHDN 3
6 AGND
COMP 4
5 FB
COMP 4
5 FB
7 PGND
DS21921C-page 1
MCP1612
Functional Block Diagram
VCC
Undervoltage
Lockout
(UVLO)
UVLO
VIN
ISENSE P-Channel
Slope Comp.
+
+
Peak Current
Limit
Comp
VREF
FB
–
gm
+
Disable
PDRV
Disable
INSET
Circuit
LX
NDRV
IN
SoftStart
Disable
VREF
Peak Current
Limit
1.4 MHz Clock
PGND
LeadingEdge
Blank
PGND
VCC
VCC
UVLO
1.2V
A
VBG
SHDN
Disable
AGND
0.8V
Thermal
Shutdown
AGND
AGND
DS21921C-page 2
2004-2013 Microchip Technology Inc.
MCP1612
Typical Application Circuit
MCP1612 3.3V to 1.2V Synchronous Buck Converter
3.3 VIN ±10%
CIN
10 µF
Ceramic
ON
1
VIN
Lx
8 L = 3.3 µH
MCP1612
10
2
CBYP
0.1 µF
Ceramic
3
VCC
PGND
SHDN
AGND
7
1.2V VOUT @ 1A
COUT
10 µF
Ceramic
100 k
6
200 k
OFF
4
Comp
FB
5
25 k
1000 pF
2004-2013 Microchip Technology Inc.
DS21921C-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 †
VIN – AGND .......................................................................6.0V
(SHDN, FB, VCC, Comp ........... (AGND – 0.3V) to (VIN + 0.3V)
LX to PGND .............................................. -0.3V to (VIN + 0.3V)
PGND to AGND................................................... -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)300V
DC CHARACTERISTICS
Electrical Specifications: Unless otherwise noted, VIN = VCC = VSHDN = 3.3V, VOUT = 1.8V, CIN = COUT = 10 µF, L = 3.3 µH,
ILOAD = 100 mA, TA = +25°C. Boldface specifications apply over the TA range of -40°C to +85°C.
Parameters
Sym
Min
Typ
Max
Units
Conditions
Input Voltage
Input Operating Voltage
VIN
2.7
—
5.5
V
Input Shutdown Current
I(VIN)
—
0.01
1
µA
Shutdown mode (SHDN = GND)
Input Quiescent Current
I(VIN)
—
5
7
mA
ILOAD = 0 mA
FOSC
1.2
1.4
1.6
MHz
RDSon P-Channel
RDSon-P
—
300
—
m
IP = 250 mA
RDSon N-Channel
RDSon-N
—
300
—
m
IN = 250 mA
ILX
-1
—
1
µA
SHDN = 0V, VIN = 5.5V, LX = 0V,
LX = 5.5V
Positive Current Limit Threshold
+ILX(MAX)
—
2.3
—
A
Negative Current Limit Threshold
-ILX(MAX)
—
-1.4
—
A
gm
35
62
90
µA/V
Oscillator Characteristics
Internal Oscillator Frequency
Internal Power Swicthes
LX Pin Leakage Current
Feedback Characteristics
Transconductance from FB to
COMP
Output Voltage
Output Voltage Range
Reference Feedback Voltage
Feedback Input Bias Current
VOUT
0.8
—
VIN
V
VFB
0.78
0.8
0.82
V
IVFB
—
1
—
nA
Line Regulation
VLINE-REG
—
0.15
0.5
%/V
Load Regulation
VLOAD-REG
—
0.25
—
%
Note 1:
2:
VIN = 2.7V to 5.5V, ILOAD = 100 mA
VIN = 4.2V, ILOAD = 100 mA to 1A
The integrated MOSFET switches have an integral diode from the LX pin to VIN and from LX to PGND. In cases where
these diodes are forward-biased, the package power dissipation limits must be adhered to. Thermal protection is not
able to regulate the junction temperature for these cases.
UVLO is specified for a falling VIN. Once the UVLO is activated, the UVLO-HYS must be overcome before the device will
return to operation.
DS21921C-page 4
2004-2013 Microchip Technology Inc.
MCP1612
DC CHARACTERISTICS (CONTINUED)
Electrical Specifications: Unless otherwise noted, VIN = VCC = VSHDN = 3.3V, VOUT = 1.8V, CIN = COUT = 10 µF, L = 3.3 µH,
ILOAD = 100 mA, TA = +25°C. Boldface specifications apply over the TA range of -40°C to +85°C.
Parameters
Sym
Min
Typ
Max
Units
UVLO
2.4
2.55
2.7
V
UVLO-HYS
—
200
—
mV
TSHD
—
160
—
°C
TSHD-HYS
—
9
—
°C
Logic-High Input
VIN-HIGH
45
—
—
% of VIN
Logic-Low Input
VIN-LOW
—
—
15
% of VIN
Conditions
Protection Features
Undervoltage Lockout
Undervoltage Lockout Hysteresis
Thermal Shutdown
Thermal Shutdown Hysteresis
Note 2
Note 1
Interface Signal (SHDN)
Note 1:
2:
The integrated MOSFET switches have an integral diode from the LX pin to VIN and from LX to PGND. In cases where
these diodes are forward-biased, the package power dissipation limits must be adhered to. Thermal protection is not
able to regulate the junction temperature for these cases.
UVLO is specified for a falling VIN. Once the UVLO is activated, the UVLO-HYS must be overcome before the device will
return to operation.
TEMPERATURE SPECIFICATIONS
Electrical Specifications: VIN = 3.0V to 5.5V, FOSC = 1 MHz with 10% Duty Cycle, CIN = 0.1 µF. TA = -40°C to +125°C.
Parameters
Sym
Min
Typ
Max
Units
Conditions
TA
-65
—
+150
°C
Continuous
Temperature Ranges
Storage Temperature Range
Maximum Junction Temperature
TJ
—
—
+150
°C
Transient Only
Operating Junction Temperature Range
TA
- 40
—
+ 125
°C
Continuous Operation
Thermal Resistance, 8L-MSOP
JA
—
208
—
°C/W
Typical 4-layer board interconnecting
vias
Thermal Resistance, 8L-DFN
JA
—
41
—
°C/W
Typical 4-layer board interconnecting
vias
Thermal Package Resistances
2004-2013 Microchip Technology Inc.
DS21921C-page 5
MCP1612
2.0
TYPICAL PERFORMANCE CURVES
Note:
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.
100
90
80
70
60
50
40
30
20
10
0
0.50
VOUT = 2.5V
Dropout Voltage (V)
Efficiency (%)
Note: Unless otherwise indicated, VIN = VCC = VSHDN = 3.3V, COUT = CIN = 10 µF, L = 3.3 µH, ILOAD = 100 mA,
TA = +25°C. Boldface specifications apply over the TA range of -40°C to +85°C.
VOUT = 1.2V
VOUT = 1.8V
VOUT = 2.7V
0.40
0.30
VOUT = 3.3V
0.20
0.10
VIN = 3.3V
0.00
10
100
1000
0
200
Load Current (mA)
100
90
80
70
60
50
40
30
20
10
0
Efficiency vs. Load Current,
Efficiency (%)
VOUT = 3.3V
VOUT = 2.5V
VIN = 5.0V
10
100
FIGURE 2-4:
Load Current.
Input Quiescent Current (mA)
FIGURE 2-1:
VIN = 3.3V.
6.0
5.5
TA = +85oC
5.0
o
4.5
TA = +25 C
4.0
o
TA = -40 C
VOUT = 1.8V
3.5
3
3.5
VOUT = 1.2V VIN = 3.3V
-0.4
VOUT = 1.8V, VIN = 3.3V
-0.8
-1
-1.2
VOUT = 3.3V, VIN = 5.0V
-1.4
FIGURE 2-5:
Input Voltage.
Oscillator Frequency (MHz)
Change In Output Voltage (mV)
1000
4
4.5
5
5.5
Input Voltage (V)
0
-0.6
800
6.5
2.5
1000
Efficiency vs. Load Current,
-0.2
600
Dropout Voltage vs.
Load Current (mA)
FIGURE 2-2:
VIN = 5.0V.
400
Load Current (mA)
Input Quiescent Current vs.
1.42
TA = -40oC
1.41
1.40
TA = +25oC
1.39
1.38
1.37
TA = +85oC
1.36
0
200
400
600
800
1000
2.5
Load Current (mA)
FIGURE 2-3:
Load Current.
DS21921C-page 6
Output Voltage vs.
3
3.5
4
4.5
5
5.5
Input Voltage (V)
FIGURE 2-6:
Input Voltage.
Oscillator Frequency vs.
2004-2013 Microchip Technology Inc.
MCP1612
TYPICAL PERFORMANCE CURVES (Continued)
Note: Unless otherwise indicated, VIN = VCC = VSHDN = 3.3V, COUT = CIN = 10 µF, L = 3.3 µH, ILOAD = 100 mA,
TA = +25°C. Boldface specifications apply over the TA range of -40°C to +85°C.
Start-up from VIN = 0V to 3.3V
IOUT = 100 mA to 800 mA
VIN = 5.0V
VOUT = 3.3V
VOUT
100 mV/DIV
VIN
2.0V/DIV
IOUT
500 mA/DIV
VOUT
1.0V/DIV
VOUT = 1.8V
1.0 ms/DIV
FIGURE 2-7:
500 µs/DIV
Power-Up from VIN.
FIGURE 2-10:
Load Transient Response.
Line Step Response, VIN = 3.0V to 4.0V
Start-up from SHDN
VIN
2.0V/DIV
SHDN
2.0V/DIV
VOUT
50 mV/DIV
VOUT
1.0V/DIV
VOUT = 1.8V
IOUT = 800 mA
VOUT = 1.8V
1.0 ms/DIV
FIGURE 2-8:
200 µs/DIV
Power-Up from Shutdown.
FIGURE 2-11:
Line Step Response, VIN = 4.5V to 5.5V
IOUT = 100 mA to 800 mA
VIN
2.0V/DIV
VOUT
200 mV/DIV
VOUT
50 mV/DIV
IOUT
500 mA/DIV
VOUT = 3.3V
IOUT = 800 mA
VOUT = 1.8V
50 µs/DIV
FIGURE 2-9:
Line Transient Response.
Load Transient Response.
2004-2013 Microchip Technology Inc.
200 µs/DIV
FIGURE 2-12:
Line Transient Response.
DS21921C-page 7
MCP1612
TYPICAL PERFORMANCE CURVES (Continued)
Note: Unless otherwise indicated, VIN = VCC = VSHDN = 3.3V, COUT = CIN = 10 µF, L = 3.3 µH, ILOAD = 100 mA,
TA = +25°C. Boldface specifications apply over the TA range of -40°C to +85°C.
IOUT = 10 mA, VOUT = 1.8V
IOUT = 1A, VOUT = 1.8V
LX
5.0V/DIV
LX
2.0V/DIV
VOUT
10 mV/DIV
VOUT
10 mV/DIV
IIND
500 mA/DIV
IIND
100 mA/DIV
VIN = 3.3V
VIN = 3.3V
500 ns/DIV
FIGURE 2-13:
Waveform.
DS21921C-page 8
Low Load Current Switching
500 ns/DIV
FIGURE 2-14:
Waveform.
High Load Current Switching
2004-2013 Microchip Technology Inc.
MCP1612
3.0
MCP1612 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
Pin No.
3.1
PIN FUNCTION TABLE
Name
Function
1
VIN
Input Voltage Pin
2
VCC
Analog Input Voltage Pin
3
SHDN
Shutdown Control Input Pin
4
COMP
Transconductance Amplifier Output Pin
5
FB
Feedback Input Pin
6
AGND
Analog Ground Pin
7
PGND
Power Ground Pin
8
LX
Buck Inductor Output Pin
Input Voltage Pin (VIN)
3.5
Feedback Pin (FB)
Connect the input voltage source to VIN. For normal
operation, the voltage on VIN should be between +2.7V
and +5.5V. A 10 µF bypass capacitor should be
connected between VIN and PGND.
Connect the output voltage of the buck converter
through an external resistor divider to FB to regulate
the output voltage. The nominal voltage compared to
this input for pulse termination is 0.8V.
3.2
3.6
Analog Input Voltage Pin (VCC)
VCC provides bias for internal analog functions. This
voltage is derived by filtering the VIN supply.
3.3
Tie all small-signal ground returns to AGND. Noise on
AGND can effect the sensitive internal analog
measurements.
Shutdown Input Pin (SHDN)
Connect SHDN to a logic-level input in order to turn the
regulator on or off. A logic-high (>45% of VIN) will
enable the regulator. A logic-low (
