MIC5021BM Micrel Inc, MIC5021BM Datasheet - Page 8
![IC DRIVER MOSFET HISIDE HS 8SOIC](/photos/6/50/65078/576-8-soic_sml.jpg)
MIC5021BM
Manufacturer Part Number
MIC5021BM
Description
IC DRIVER MOSFET HISIDE HS 8SOIC
Manufacturer
Micrel Inc
Datasheet
1.MIC5021YM_TR.pdf
(10 pages)
Specifications of MIC5021BM
Configuration
High-Side
Input Type
Non-Inverting
Delay Time
500ns
Number Of Configurations
1
Number Of Outputs
1
Voltage - Supply
12 V ~ 36 V
Operating Temperature
-40°C ~ 85°C
Mounting Type
Surface Mount
Package / Case
8-SOIC (3.9mm Width)
Number Of Drivers
1
Driver Configuration
Non-Inverting
Driver Type
High Side
Input Logic Level
TTL
Rise Time
500ns
Fall Time
500ns
Frequency (max)
150MHz
Operating Supply Voltage (max)
36V
Operating Supply Voltage (min)
12V
Operating Supply Voltage (typ)
15V
Turn Off Delay Time
1.5ps
Turn On Delay Time (max)
1ns
Operating Temp Range
-40C to 85C
Operating Temperature Classification
Industrial
Mounting
Surface Mount
Pin Count
8
Package Type
SOIC
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Current - Peak
-
High Side Voltage - Max (bootstrap)
-
Lead Free Status / RoHS Status
Not Compliant, Contains lead / RoHS non-compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
MIC5021BM
Manufacturer:
MICREL
Quantity:
115
MIC5021
External Protection
Resistors placed in series with each
the current drawn from the internal Schottky diodes during a
negative transient. This minimizes the forward drop across
the diodes.
During normal operation, sensing current from the sense pins
is unequal (5µA and 15µA). The internal Schottky diodes are
reverse biased and have no effect. To avoid skewing the trip
voltage, the current limiting resistors must drop equal volt-
ages at the trip point currents. See Figure 7. To minimize
resistor tolerance error, use a voltage drop lower than the
trip voltage of 50mV. 5mV is suggested.
External Schottky diodes are also recommended. See D2
and D3 in Figure 8. The external diodes clamp negative
transients better than the internal diodes because their larger
size minimizes the forward voltage drop at higher currents.
MIC5021
10µF
TTL Input
Figure 8. Protection from Inductive Kick
V
to avoid skewing
the 50mV trip point.
R 1 ≅ 3 × R 2
(5mV suggested)
1
2
3
4
R 1
V
Input
C
Gnd
= V
Figure 7. Resistor Voltage Drop
DD
T
1
2
3
4
MIC5021
R 2
V
Input
C
Gnd
DD
T
MIC5021
Sense-
Sense+
V
B O O S T
Gate
Sense-
Sense+
V
11DQ03
B O O S T
Gate
11DQ03
8
7
6
5
D2
8
7
6
5
D3
15µA
5µA
R 1
V
V
R 1
R 2
2.7
nF
1.0k
330Ω
R 1
R 2
D1
SENSE
+12V to +36V
R
N-Channel
Power MOSFET
Load
S
50mV nominal
(at trip)
N-Channel
Power MOSFET
R
S E N S E
connection limit
Inductive
Load
8
High-Side Sensing
Sensing the current on the high side of the MOSFET isolates
the
Lamp Driver Application
Incandescent lamps have a high inrush current (low resis-
tance) when turned on. The MIC5021 can perform a “soft
start” by pulsing the MOSFET (overcurrent condition) until
the filament is warm and its current decreases (resistance
increases). The sense resistor value is selected so the voltage
drop across the sense resistor decreases below the sense
threshold (50mV) as the filament becomes warm. The FET
is no longer pulsed and the lamp turns completely on.
A lamp may not fully turn on if the filament does not heat up
adequately. Changing the duty cycle, sense resistor, or both to
match the filament characteristics can correct the problem.
Soft start can be demonstrated using a #1157 dual filament
automotive lamp. The value of R
for soft start of the higher-resistance filament (measures ap-
prox. 2.1Ω cold or 21Ω hot).
TTL Input
TTL Input
SENSE
10µF
10µF
pins from the inductive spike.
"( )" values apply to demo circuit.
Figure 10. Lamp Driver with
Figure 9. High Side Sensing
1
2
3
4
1
2
3
4
V
Input
C
Gnd
See text.
Current Sensing
DD
T
Input
C
Gnd
V
MIC5021
DD
T
MIC5021
Sense-
Sense+
V
Sense+
Sense-
B O O S T
V
Gate
B O O S T
Gate
8
7
6
5
S
8
7
6
5
shown in Figure 10 allows
0.01
µF
+12V to +20V
0.01
µF
V+
(+12V)
N-Channel
Power MOSFET
(IRF540)
R
(0.041Ω)
(+12V)
R
(< 0.01Ω)
N-Channel
Power MOSFET
(IRFZ44)
S E N S E
S E N S E
Incandescent
Lamp (#1157)
Wirewound
Resistor
(3Ω)
Micrel, Inc.
July 2005