Datasheet

 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
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
Equation 5-6.
EQUATION 5-6: DIODE AVERAGE
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.
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
IN
.
TABLE 5-3: MCP16301/H RECOMMENDED
3.3V INDUCTORS
Part Number
Value
(µH)
DCR ()
I
SAT
(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
B0540Ws-7 40V, 0.5A
18 V
IN
600 mA
Diodes
Incorporated
B130L-13-F 30V, 1A
I
D1AVG
1D–I
OUT
 =
I
OUT
=0.5A
V
IN
=15V
V
OUT
=5V
D=5/15
I
D1AVG
=333mA