Information

13
Portable Power Conversion Design Guide
DC/DC Conversion
Step-Up (Boost) Switch Mode Power Converters
MCP1640 High Performance PFM/PWM Synchronous Boost Converter with True Output
Disconnect or Input/Output Bypass Options
The MCP1640 is a compact, high-efficiency, fixed-frequency, synchronous step-up DC-DC converter. It provides an easy-to-use
power supply solution for applications powered by one-, two-, or three-cell alkaline, NiCd, NiMH; one-cell Li-ion; or one-cell
Li-polymer batteries. It provides very high efficiency through integration of the low-resistance n-channel boost switch and
synchronous p-channel switch, and is available with PFM/PWM, PWM only, true load disconnect or bypass options.
■ Typical efficiency up to 96%
■ High current output:
• I
out > 100 mA at Vout = 3.3V and Vin = 1.2V
• Iout > 350 mA at Vout = 3.3V and Vin = 2.4V
• Iout > 350 mA at Vout = 5.0V and Vin =3.3V
■ Low 0.65V typical start-up input voltage
(3.3V Vout at 1 mA)
■ Low 0.35V typical operating input voltage
(3.3V Vout at 1 mA)
■ Wide 2.0V to 5.5V adjustable output voltage range
■ Maximum input voltage ≤ Vout < 5.5V
■ High frequency 500 kHz PWM operation, with PFM and
PWM device options:
• Automatic PFM/PWM operation (MCP1640/C)
• PWM only, PFM operation disabled (MCP1640B/D)
■ Selectable, logic-controlled, shutdown states:
• True load disconnect option (MCP1640/B)
• Input to output bypass option (MCP1640C/D)
■ Low < 1 μA shutdown current (all states)
■ Low 19 μA typical device quiescent current
■ Internal synchronous rectifier
■ Internal compensation
■ Inrush current limiting
■ Internal soft-start
■ Low noise, anti-ringing control
■ Over-temperature protection
■ Available in 6-lead SOT-23 and 8-lead 2 × 3
DFN packages
MCP1640 Application Circuit Using a Single Cell
Alkaline Battery
GND
V
IN
EN
SW
V
FB
VOUT
VOUT
3.3V @ 100 mA
VIN
0.9V TO 1.7V
COUT
10 μF
C
IN
4.7 μF
976 kΩ
562 kΩ
L
1
4.7 μH
MCP1640 Typical Efficiency for a 3.3V Output
0
10
20
30
40
50
60
70
80
90
100
0.01 0.1 1 10 100 1000
Efficiency (%)
I
OUT
(mA)
V
OUT
= 3.3V
V
IN
= 0.8V
V
IN
= 1.2V
V
IN
= 2.5V
MCP1640 Application Circuit Using a Single Cell
Li-ion Battery
PGND SGND
VIN
EN
SW
V
FB
VOUTS
VOUTP
VOUT
5.0V @ 300 mA
V
IN
3.0V
TO 4.2V
COUT
10 μF
C
IN
4.7 μF
976 kΩ
309 kΩ
L
1
4.7 μH