MCP1612-250I/MS Microchip Technology, MCP1612-250I/MS Datasheet - Page 11

• Manufacturer Part Number: MCP1612-250I/MS
• Description: Switching Converters, Regulators & Controllers 1.4MHz 1A Synch-Buck
• Manufacturer: Microchip Technology

Specifications of MCP1612-250I/MS

• Output Current: 1.0 A
• Mounting Style: SMD/SMT
• Package / Case: MSOP-8
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

5.0
FIGURE 5-1:
5.1
The MCP1612 Buck controller can be used in several
different applications where a voltage that is lower than
the supply voltage is required. The small size, low-cost,
and high efficiency make the MCP1612 a good choice
for densely packaged applications. The input voltage
range, low dropout voltage and low shutdown current
make this part perfectly suited for battery-powered
applications.
5.2
The step-by-step design of a Buck converter with the
following parameters is designed to show how easy the
MCP1612 is to use.
5.2.1
The output voltage of the MCP1612 is set by using an
external resistor divider network. The voltage present
at the feedback input pin (FB) is internally compared to
a 0.8V reference voltage. A 200 k
mended for R
 2004 Microchip Technology Inc.
Switching frequency = 1.4 MHz
OFF
3.3V
Output voltage = 1.2V
Output current = 0A to 1A
APPLICATION CIRCUITS/INFORMATION
Typical Applications
Design Example
Input voltage = 3.3V
Ceramic
SETTING OUTPUT VOLTAGE
IN
10 µF
ON
2
±10%
, the lower end of the voltage divider.
C
IN
Typical Application Circuit.
Ceramic
0.1 µF
C
MCP1612 3.3V to 1.2V Synchronous Buck Converter
1000 pF
byp
25 k
10
resistor is recom-
1
2
3
4
V
V
SHDN
Comp
IN
CC
MCP1612
Using higher value resistors will make the circuit more
susceptible to noise on the FB pin. Lower value
resistors can be used, if necessary.
Equation 5-1 used to calculate the output voltage is
shown below.
EQUATION 5-1:
For this example:
The MCP1612 is capable of a 15% duty cycle. Instabil-
ity may result when the duty cycle is below 15%. If less
than 15% duty cycle operation is needed, care must be
taken to ensure stable operation.
P
A
Where:
GND
GND
FB
L
x
V
V
OUT
8
7
6
5
FB
R
R
1
2
L = 3.3 µH
= top resistor value
= desired output voltage
= MCP1612 internal reference voltage
= bottom resistor value
R
1
V
=
OUT
V
R
R
FB
R
2
1
2
= 1.2V
= 0.8V
= 200 k
= 100 k


C
10 µF
Ceramic
V
------------- 1
V
OUT
OUT
FB
MCP1612
1.2V V
–


DS21921A-page 11
OUT
100 k
200 k
@ 1A