MIC38C45-1BM Micrel Inc, MIC38C45-1BM Datasheet - Page 8
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MIC38C45-1BM
Manufacturer Part Number
MIC38C45-1BM
Description
IC CTRLR PWM CURRENT MODE 14SOIC
Manufacturer
Micrel Inc
Datasheet
1.MIC38C42YN.pdf
(11 pages)
Specifications of MIC38C45-1BM
Pwm Type
Current Mode
Number Of Outputs
1
Frequency - Max
500kHz
Duty Cycle
50%
Voltage - Supply
7.6 V ~ 20 V
Buck
Yes
Boost
Yes
Flyback
Yes
Inverting
No
Doubler
No
Divider
No
Cuk
No
Isolated
Yes
Operating Temperature
-40°C ~ 85°C
Package / Case
14-SOIC (3.9mm Width), 14-SOL
Frequency-max
500kHz
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
MIC38C42/3/4/5
Synchronous Buck Converter
Refer to figure 2. This MIC38C43 synchronous buck converter
uses an MIC5022 half-bridge driver to alternately drive the
PWM switch MOSFET (driven by GATEH, or high-side output)
and a MOSFET which functions as a synchronous rectifier
(driven by the GATEL, or low-side output).
The low-side MOSFET turns on when the high-side MOS-
FET is off, allowing current to return from ground. Current
flows through the low-side MOSFET in the source to drain
direction.
M9999-091107
Test
Line Regulation
Load Regulation V
Efficiency
Output Ripple
2200
6.8k
pF
Conditions
V
V
V
47k
3.3k
10k
IN
IN
IN
IN
= 26V to 80V, I
= 48V, I
= 48V, I
= 48V, I
10k
300k
4.3k
4.7nF
0.15µF
O
O
O
= 0.2A to 2A
= 2A
= 2A (20MHz BW)
COM P
F B
I S N S
RT/CT
MIC38C43
*Locate near the MIC38C43 supply pins.
O
Figure 2. 100kHz, Synchronous Buck Converter
= 2A
VOUT
V R E F
GND
VDD
0.1µF*
MKS2
0.1µF
470µF
25V
Results
100mV
0.5%
0.6%
90%
+12V
NC
NC
NC
8
1. Custom Coils, Alcester, SD tel: (605) 934-2460
2. Energy Transformation Systems, Inc. tel: (415) 324-4949.
The on-state voltage drop of the low-side MOSFET is lower
than the forward voltage drop of an equivalent Schottky recti-
fier. This lower voltage drop results in higher efficiency.
A sense resistor (5mΩ) is connected to the driver’s high-
side current sense inputs to provide overcurrent protection.
Refer to the MIC5020, MIC5021, and MIC5022 data sheets
for more information.
Symbol
CT1
T1
L1
VDD
FL T
E N
IN
C T
GND
MIC5022
G A T E H
G A T E L
SH+
SH–
SL+
S L–
V B
Custom Coil
4923
4924
4925
0.1µF
SMP60N06-14
5mΩ
1
35µH
ETS
ETS 92420
ETS 92419
ETS 92421
1000µF
Low ESR
2
5V, 8A
September 2007
V
OUT
Micrel, Inc.