MIC38C42BM Micrel Inc, MIC38C42BM Datasheet - Page 8

• Manufacturer Part Number: MIC38C42BM
• Description: IC CTRLR PWM CURRENT MODE 8-SOIC
• Manufacturer: Micrel Inc

Specifications of MIC38C42BM

• Duty Cycle: 96%
• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 500kHz
• Voltage - Supply: 9 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: 8-SOIC (3.9mm Width)
• Frequency-max: 500kHz
• Number Of Pwm Outputs: 1
• On/off Pin: No
• Adjustable Output: No
• Switching Freq: 500KHz
• Operating Supply Voltage (max): 20V
• Output Current: 500A
• Synchronous Pin: No
• Rise Time: 40ns
• Fall Time: 30ns
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 8
• Package Type: SOIC
• 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: [phone]
2. Energy Transformation Systems, Inc. tel: [phone].
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.