Datasheet

 2004-2013 Microchip Technology Inc. DS21876B-page 15
MCP1650/51/52/53
5.0 APPLICATION CIRCUITS/
ISSUES
5.1 Typical Applications
The MCP1650/51/52/53 boost controller can be used in
several different configurations and in many different
applications. For applications that require minimum
space, low cost and high efficiency, the MCP1650/51/
52/53 product family is a good choice. It can be used in
boost, buck-boost, Single-Ended Primary Inductive
Converters (SEPIC), as well as in flyback converter
topologies.
5.1.1 NON-BOOTSTRAP BOOST
APPLICATIONS
Non-bootstrap applications are typically used when the
output voltage is boosted to a voltage that is higher
than the rated voltage of the MCP1650/51/52/53. For
non-bootstrap applications, the input voltage is
connected to the boost inductor through the optional
current sense resistor and the V
IN
pin of the MCP1650/
51/52/53. For this type of application, the S-option
devices (UVLO at 2.55V, typical) should be used. The
gated oscillator duty cycle will be dependant on the
value of the voltage on V
IN
. If V
IN
> 3.8V, the duty cycle
will be 56%. If V
IN
< 3.8V, the duty cycle will be 80%.
In non-bootstrap applications, output voltages of over
100V can be generated. Even though the MCP1650/
51/52/53 device is not connected to the high boost
output voltage, the drain of the external MOSFET and
reverse voltage of the external Schottky diode are
connected. The output voltage capacitor must also be
rated for the output voltage.
FIGURE 5-1: Typical Non-Bootstrap Application Circuit (MCP1650/51/52/53).
FB
CS
SHDN
V
IN
8
2
5
6
4
7
MCP1650
GND
Input
Voltage
3.3V ±10%
C
IN
10 µF
off
on
EXT
Boost
Inductor
3.3 µH
C
OUT
10 µF
Ceramic
90.9 k
V
OUT
= 12V
I
OUT
= 0 to 100 mA
10 k
MOSFET/Schottky
Combination Device
R
SENSE
0.05 
3.3V to 12V 100 mA Boost Converter
1
3
NC
NC