MIC5021_05 Datasheet, PDF (2/10 Pages) Micrel Semiconductor – High-Speed High-Side MOSFET Driver

MIC5021
Pin Configuration
Block Diagram
1 V_DD
2 Input
V_BOOST 8
Gate ₇
3 ^C_T
4 Gnd
Sense- ₆
Sense+ 5
DIP Package
(N)
1 V_DD V_BOOST 8
2 Input ^Gate 7
3 ^C_T ^Sense- 6
4 Gnd Sense+ 5
SOIC Package
(M)
6V Internal Regulator
I₁
C_INT
2I₁
Fault
Normal
Q1
C_T
V_DD
CHARGE
PUMP
V_{B OOS T}
Micrel, Inc.
Sense+
Sense-
50mV
Input
Transistor: 106
Pin Description
Pin Number
1
2
3
Pin Name
V_DD
Input
C_T
4
Gnd
5
Sense +
6
Sense –
7
Gate
8
V_BOOST
↑ _ONE-
↓ ^SHOT
10I₂
ON
OFF _6V
I₂
15V
Gate
Pin Function
Supply: +12V to +36V. Decouple with ≥ 10µF capacitor.
TTL Compatible Input: Logic high turns the external MOSFET on. An inter-
nal pull-down returns an open pin to logic low.
Retry Timing Capacitor: Controls the off time (t_G(OFF)) of the overcurrent
retry cycle. (Duty cycle adjustment.)
• Open = approx. 20% duty cycle.
• Capacitor to Ground = approx. 20% to < 1% duty cycle.
• Pull-up resistor = approx. 20% to approx. 75% duty cycle.
• Ground = maintained shutdown upon overcurrent condition.
Circuit Ground
Current Sense Comparator (+) Input: Connect to high side of sense resistor
or current sensing MOSFET sense lead. A built-in offset in conjunction with
R_SENSE sets the load overcurrent trip point.
Current Sense Comparator (–) Input: Connect to the low side of the sense
resistor (usually the high side of the load).
Gate Drive: Drives the gate of an external power MOSFET. Also limits V_GS
to 15V max. to prevent Gate-to-Source damage. Will sink and source cur-
rent.
Charge Pump Boost Capacitor: A bootstrap capacitor from V_BOOST to the
FET source pin supplies charge to quickly enhance the Gate output during
turn-on.
MIC5021
2
July 2005