Document
MIC5022
Micrel
MIC5022
Half-Bridge MOSFET Driver
General Description
The MIC5022 half-bridge MOSFET driver is designed to operate at frequencies up to 100kHz (5kHz PWM for 2% to 100% duty cycle) and is an ideal choice for high speed applications such as motor control and SMPS (switch mode power supplies). A rising or falling edge on the input results in a current source pulse or sink pulse on the gate outputs. This output current pulse can turn on a 2000pF MOSFET in approximately 1µs. The MIC5022 then supplies a limited current (< 2mA), if necessary, to maintain the output states. Two overcurrent comparators with nominal trip voltages of 50mV make the MIC5022 ideal for use with current sensing MOSFETs. External low value resistors may be used instead of sensing MOSFETs for more precise overcurrent control. Optional external capacitors placed on the CTH and CTL pins may be used to individually control the current shutdown duty cycles from approximately 20% to <1%. Duty cycles from 20% to about 75% are possible with individual pull-up resistors from CTL and CTH to VDD. An open collector output provides a fault indication when either sense input is tripped. The MIC5022 is available in 16-pin wide SOIC and 14-pin plastic DIP packages. Other members of the MIC502x family include the MIC5020 low-side driver and the MIC5021 high-side driver.
Features
• • • • • • • • • • 12V to 36V operation 600ns rise time into 1000pF (high side) TTL compatible input with internal pull-down resistor Outputs interlocked to prevent cross conduction TTL compatible enable Fault output indication Individual overcurrent limits Gate protection Internal charge pump (high-side) Current source drive scheme reduces EMI
Applications
• Motor control • Switch-mode power supplies
Ordering Information
Part Number MIC5022BWM MIC5022BN Temperature Range –40°C to +85°C –40°C to +85°C Package 16-pin Wide SOIC 14-pin Plastic DIP
Typical Application
+12V to +36V
1 10µF TTL Input (PWM signal) 2 3 4 CTH 5 6 CTL 7
MIC5022 VDD Input VBOOST Gate H
14 13 12 11 10 9 8 RS2 RS1 M 2.7nF
Fault Sense H– CTH Enable CTL Gnd Sense H+ Gate L Sense L– Sense L+
DC Motor Control Application
MIC5022
178
September 1999
MIC5022
Micrel
Pin Configuration
1 VDD 2 Input 3 Fault 4 CTH 5 Enable 6 CTL 7 Gnd VBOOST 14 Gate H 13 Sense H– 12 Sense H+ 11 Gate L 10 Sense L– 9 Sense L+ 8 1 2 3 4 5 6 7 8 VDD NC Input NC 16 VBOOST 15 Gate H 14
Fault Sense H– 13 CTH Sense H+ 12 Gate L 11
Enable CTL Gnd
Sense L– 10 Sense L+ 9
DIP Package (N)
SOIC Package (WM)
Pin Description
DIP Pin No. 1 2 SOIC Pin No. 1 3 Pin Name VDD Input Pin Function Supply: +12V to +36V. Decouple with ≥ 10µF capacitor. TTL Compatible Input: Logic high turns the high-side external MOSFET on and the low-side external MOSFET off. Logic low turns the high-side external MOSFET off and the low-side external MOSFET on. An internal pull-down returns an open pin to logic low. When either sense voltage exceeds threshold, open collector output is open circuit for 5µs (tG(ON)), then pulled low for tG(OFF). tG(OFF) is adjustable from CT. Retry Trimming Capacitor, High Side: Controls the off time (tG(OFF)) of the overcurrent retry cycle. (Duty cycle adjustment.) • Open = approx. 20% duty cycle. • Capacitor to Ground = approx. 20% to < 1% duty cycle. • Pullup resistor = approx. 20% to approx. 75% duty cycle. • Ground = maintained shutdown upon overcurrent condition. Output Enable: Disables operation of the output drivers; active high. An internal pull-down returns an open pin to logic low. Retry Trimming Capacitor, Low Side: Same function as CTH. Circuit Ground Current Sense Comparator (+) Input, Low Side: Connect to source of lowside MOSFET. A built-in offset (nominal 50mV) in conjunction with RSENSE sets the load overcurrent trip point. Current Sense Comparator (–) Input, Low Side: Connect to the negative side of the low-side sense resistor. Gate Drive, Low Side: Drives the gate of an external power MOSFET. Also limits VGS to 15V max. to prevent Gate to Source damage. Will sink and source current. Current Sense Comparator (+) Input, High Side: Connect to source of highside MOSFET. A built-in offset (nominal 50mV) in conjunction with RSENSE sets the load overcurrent trip point. Current Sense Comparator (–) Input, High Side: Connect to the negative side of the high-side sense resistor. Gate Drive, High Side: Drives the gate of an external power MOSFET. Also limits VGS to 15V max. to prevent Gate to Source damage. Will sink and source current. Charge Pump Boost Capacitor: A bootstrap capacitor from VBOOST to the MOSFET source pin supplies charge to quickly enhance the external MOSFET’s gate .
3
4
Fault
4
5
CTH
5 6 7 8
6 7 8 8
Enable CTL Gnd Sense L +
9 10
10 11
Sense L – Gate L
11
12
Sense H +
12 13
13 14
Source H – Gate H
14
15
VBOOST
September 1999
179
MIC5022
MIC5022
Micrel
Block Diagram
6V Internal Regulator I1 CINT 2I1 Sense H+ Sense H– 50mV 15V 1.4V
Fault
Normal
CTH VDD CHA.