MIC5012

Micrel

5-118

April 1998

03

69

12

15

SUPPLY VOLTAGE (V)

GATE

C

=10 nF

GATE

C

=1 nF

0

10

20

30

40

50

Turn-off Time

0.5

0.75

1.0

1.25

1.5

1.75

2.0

–25

0

25

50

75

100 125

DIE TEMPERATURE (

°C)

Turn-on Time

0

50

100

150

200

250

0

5

10

15

20

25

30

SUPPLY VOLTAGE (V)

Charge Pump

Output Current

V

=V

GATE

+

V

=V +5V

GATE

+

VS=V –5V

+

Block Diagram

CHARGE

PUMP

LOGIC

MIC5012

Ground

500

Ω

V+

Gate

Source

Input

12.5V

CHARGE

PUMP

LOGIC

500

Ω

V+

Gate

Source

Input

12.5V

312

4

2

14

10

6

5

11

Applications Information

Functional Description (Refer to Block Diagram)

The MIC5012 consists of two independent drivers sharing

a common ground. The functions are controlled via a logic

block connected to the logic input. When the input is low, all

functions are turned off for low standby current and the gate

of the power MOSFET is also held low through 500

Ω to an

N-channel switch. When the input is taken above the turn-

on threshold (3.5V typical), the N-channel switch turns off

and the charge pump is turned on to charge the gate of the

power FET.

The charge pump incorporates a 100kHz oscillator and on-

chip pump capacitors capable of charging 1nF to 5V above

supply in 60

µs typical. The charge pump is capable of

pumping the gate up to over twice the supply voltage. For

this reason, a zener clamp (12.5V typical) is provided

between the gate pin and source pin to prevent exceeding

the V

Since the supply pins are independent, the two drivers

contained in the MIC5012 can be operated from separate

supplies of different values (see Figure 6).

Construction Hints

High current pulse circuits demand equipment and assem-

bly techniques that are more stringent than normal, low

current lab practices. The following are the sources of