MIC5012
Micrel
Typical Characteristics
(Continued)
Turn-off Time
NORMALIZED TURN-ON TIME
50
Turn-on Time
2.0
1.75
1.5
1.25
1.0
0.75
0.5
–25
0
25
50
75
100 125
TURN-OFF TIME (µS)
40
30
20
10
0
0
CGATE =10 nF
CGATE =1 nF
3
6
9
12
15
SUPPLY VOLTAGE (V)
DIE TEMPERATURE (°C)
CHARGE-PUMP CURRENT (µA)
Charge Pump
Output Current
250
VGATE =V+
200
150
VGATE =V++5V
100
50
VS=V +–5V
0
0
5
10
15
20
25
30
Block Diagram
MIC5012
Ground
3
V+
12
CHARGE
PUMP
500Ω
4 Gate
12.5V
Input 14
LOGIC
2 Source
SUPPLY VOLTAGE (V)
V+
10
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 500Ω 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 60µs 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
CHARGE
PUMP
500Ω
6 Gate
12.5V
Input 11
LOGIC
5 Source
the V
GS
rating of the MOSFET at high supplies.
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
April 1998
5-118
MICREL [ MICREL SEMICONDUCTOR ]
