MIC5021BN Micrel Inc, MIC5021BN Datasheet - Page 6

• Manufacturer Part Number: MIC5021BN
• Description: IC DRIVER MOSFET HI SIDE HS 8DIP
• Manufacturer: Micrel Inc

Specifications of MIC5021BN

• 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: Through Hole
• Package / Case: 8-DIP (0.300", 7.62mm)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Peak: -
• High Side Voltage - Max (bootstrap): -

MIC5021
Logic-Level MOSFET Precautions
Logic-level MOSFETs have lower maximum gate-to-source
voltage ratings (typically ±10V) than standard MOSFETs
(typically ±20V). When an external MOSFET is turned on,
the doubling effect of the boost capacitor can cause the
gate-to-source voltage to momentarily exceed 10V. Internal
zener diodes clamp this voltage to 16V maximum which
is too high for logic-level MOSFETs. To protect logic-level
MOSFETs, connect a zener diode (5V≤V
gate to source.
Overcurrent Limiting
A 50mV comparator is provided for current sensing. The low
level trip point minimizes I
is used for current sensing.
The adjustable retry feature can be used to handle loads with
high initial currents, such as lamps or heating elements, and
can be adjusted from the C
C
overcurrent condition.
C
The default duty cycle (C
to the electrical characteristics when selecting a capacitor for
reduced duty cycle.
C
Increasing the duty cycle increases the power dissipation
in the load and MOSFET under a “fault” condition. Circuits
may become unstable at a duty cycle of about 75% or higher,
depending on conditions. Caution: The MIC5021 may be
damaged if the voltage applied to C
maximum voltage rating.
Boost Capacitor Selection
The boost capacitor value will vary depending on the supply
voltage range.
MIC5021
T
T
T
through a pull-up resistor to V
open, or a capacitor to ground, causes automatic retry.
to ground maintains gate drive shutdown following an
10µF
TTL Input
Figure 1. 12V to 20V Configuration
1
2
3
4
V
Input
C
Gnd
DD
T
MIC5021
T
open) is approximately 20%. Refer
2
V
Sense-
Sense+
T
R losses when a power resistor
B O O S T
Gate
connection.
DD
8
7
6
5
increases the duty cycle.
T
exceeds the absolute
+12V to +20V
0.01
µF
Zener
Load
<10V) from
6
A 0.01µF boost capacitor is recommended for best perfor-
mance in the 12V to 20V range. Refer to figure 1. Larger
capacitors may damage the MIC5021.
If the full 12V to 36V voltage range is required, the boost
capacitor value must be reduced to 2.7nF. Refer to Figure
2. The recommended configuration for the 20V to 36V range
is to place the capacitor is placed between V
as shown in Figure 3.
Do not use both boost capacitor between V
MOSFET source and V
Current Sense Resistors
Lead length can be significant when using low value (< 1Ω)
resistors for current sensing. Errors caused by lead length
can be avoided by using four-teminal current sensing re-
sistors. Four-terminal resistors are available from several
manufacturers.
Figure 3. Preferred 20V to 36V Configuration
10µF
TTL Input
10µF
TTL Input
Figure 2. 12V to 36V Configuration
1
2
3
4
1
2
3
4
V
Input
C
Gnd
V
Input
C
Gnd
DD
T
DD
T
MIC5021
MIC5021
BOOST
V
Sense-
Sense+
V
Sense-
Sense+
B O O S T
Gate
BOOST
Gate
and V
8
7
6
5
8
7
6
5
DD
+12V to +36V
+12V to +36V
2.7
nF
0.01
µF
at the same time.
DD
BOOST
Load
Load
and V
Micrel, Inc.
July 2005
and the
BOOST