Microchip Technology ADM00352 Data Sheet
2011-2013 Microchip Technology Inc.
DS20005004C-page 19
MCP16301/H
5.7
Freewheeling Diode
The freewheeling diode creates a path for inductor
current flow after the internal switch is turned off. The
average diode current is dependent upon output load
current at duty cycle (D). The efficiency of the converter
is a function of the forward drop and speed of the
freewheeling diode. A low forward drop Schottky diode
is recommended. The current rating and voltage rating
of the diode is application dependent. The diode
voltage rating should be a minimum of V
current flow after the internal switch is turned off. The
average diode current is dependent upon output load
current at duty cycle (D). The efficiency of the converter
is a function of the forward drop and speed of the
freewheeling diode. A low forward drop Schottky diode
is recommended. The current rating and voltage rating
of the diode is application dependent. The diode
voltage rating should be a minimum of V
IN
, plus margin.
For example, a diode rating of 40V should be used for
an application with a maximum input of 30V. The
average diode current can be calculated using
an application with a maximum input of 30V. The
average diode current can be calculated using
.
EQUATION 5-6:
DIODE AVERAGE
CURRENT
CURRENT
EXAMPLE 5-4:
A 0.5A to 1A diode is recommended.
5.8
Boost Diode
The boost diode is used to provide a charging path from
the low voltage gate drive source, while the switch
node is low. The boost diode blocks the high voltage of
the switch node from feeding back into the output
voltage when the switch is turned on, forcing the switch
node high.
the low voltage gate drive source, while the switch
node is low. The boost diode blocks the high voltage of
the switch node from feeding back into the output
voltage when the switch is turned on, forcing the switch
node high.
A standard 1N4148 ultra-fast diode is recommended
for its recovery speed, high voltage blocking capability,
availability and cost. The voltage rating required for the
boost diode is V
for its recovery speed, high voltage blocking capability,
availability and cost. The voltage rating required for the
boost diode is V
IN
.
TABLE 5-3:
MCP16301/H RECOMMENDED
3.3V INDUCTORS
3.3V INDUCTORS
Part Number
Va
lu
e
(µH)
DCR (
)
I
SA
T
(A)
Size
WxLxH
(mm)
Coilcraft
ME3220
15
0.52
0.90
3.2x2.5x2.0
LPS4414
15
0.440
0.92
4.3x4.3x1.4
LPS6235
15
0.125
2.00
6.0x6.0x3.5
MSS6132
15
0.135
1.56
6.1x6.1x3.2
MSS7341
15
0.057
1.78
7.3x7.3x4.1
ME3220
15
0.520
0.8
2.8x3.2x2.0
LPS3015
15
0.700
0.61
3.0x3.0x1.4
Wurth Elektronik Group
744025
15
0.400 0.900
2.8x2.8x2.8
744031
15
0.255 0.450 3.8x3.8x1.65
744042
15
0.175
0.75
4.8x4.8x1.8
Coiltronics
SD12
15
0.48
0.692
5.2x5.2x1.2
SD18
15
0.266 0.831
5.2x5.2x1.8
SD20
15
0.193 0.718
5.2x5.2x2.0
SD3118
15
0.51
0.75
3.2x3.2x1.8
SD52
15
0.189
0.88
5.2x5.5.2.0
Sumida Corporation
CDPH4D19F
15
0.075
0.66
5.2x5.2x2.0
CDRH3D161H
15
0.328
0.65
4.0x4.0x1.8
TDK - EPC
VLF30251
15
0.5
0.47
2.5x3.0x1.2
VLF4012A
15
0.46
0.63
3.5x3.7x1.2
VLF5014A
15
0.28
0.97
4.5x4.7x1.4
B82462G4332M
15
0.097
1.05
6x6x2.2
TABLE 5-4:
FREEWHEELING DIODES
App
Manufacturer
Part
Number
Rating
12 V
IN
600 mA
Diodes
®
Incorporated
DFLS120L-7
20V, 1A
24 V
IN
100 mA
Diodes
Incorporated
Incorporated
B0540Ws-7
40V, 0.5A
18 V
IN
600 mA
Diodes
Incorporated
Incorporated
B130L-13-F
30V, 1A
I
D1AVG
1
D
–
I
OUT
=
I
OUT
= 0.5A
V
IN
= 15V
V
OUT
= 5V
D
= 5/15
I
D1AVG
= 333 mA