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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 1s. 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 -40C to +85C -40C to +85C Package 16-pin Wide SOIC 14-pin Plastic DIP
Typical Application
+12V to +36V
1 10F 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
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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 10F 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 5s (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
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MIC5022
MIC5022
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Block Diagram
6V Internal Regulator I1 CINT 2I1 Sense H+ Sense H- 50mV 15V 1.4V
Fault
Normal
CTH VDD CHARGE PUMP
VBOOST
Q1
ON
Input ONE SHOT 10I2 I2
OFF
6V Gate H
6V I1 CINT 2I1 Sense L+ Sense L- 50mV VDD 15V 1.4V ONE SHOT Enable 10I2 I2
ON OFF
Fault
CTL
Normal
Fault
Q1
6V Gate L
Transistor Count: 188
Absolute Maximum Ratings
Supply Voltage (VDD) .................................................. +40V Input Voltage .................................................. -0.5V to 15V Sense Differential Voltage .......................................... 6.5V Sense + or Sense - to Gnd .......................... -0.5V to +36V Fault Voltage ............................................................... +36V Current into Fault ....................................................... 50mA Timer Voltage (CT) ..................................................... +5.5V VBOOST Capacitor .................................................... 0.01F MIC5022 180
Operating Ratings
Supply Voltage (VDD) .................................... +12V to +36V Temperature Range SOIC ...................................................... -40C to +85C PDIP ....................................................... -40C to +85C
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MIC5022
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Electrical Characteristics
TA = 25C, Gnd = 0V, VDD = 12V, Gate CL = 1500pF (IRF540 MOSFET) unless otherwise specificed Symbol Parameter Condition Min D.C. Supply Current VDD = 12V, Input = 0V VDD = 36V, Input = 0V VDD = 12V, Input = 5V VDD = 36V, Input = 5V Input Threshold Input Hysteresis Input Pull-Down Current Enable Threshold Enable Hysteresis Fault Output Saturation Voltage Fault Output Leakage Current Limit Thresh., Low-Side Current Limit Thresh., High-Side Gate On Voltage, High-Side Fault Current = 1.6mA Note 1 Fault = 36V Note 2 Note 2 VDD = 12V, Note 3 VDD = 36V, Note 3 Gate On Voltage, Low-Side VDD = 12V, Note 3 VDD = 36V, Note 3 tG(ON) tG(OFF) tDLH tR tDHL tF tDLH tR tDHL tF
Note 1 Note 2 Note 3 Note 4 Note 5 Note 6 Note 7 Note 8 Note 9
Typ 2.5 6.0 2.4 3.0
Max 5 10 5 25 2.0
Units mA mA mA mA V V A V V
0.8
1.4 0.1
Input = 5V
10 0.8
20 1.4 0.1 0.15
40 2.0
0.4 +1 70 70 21 52
V A mV mV V V V
-1 30 30 16 46 10 14 2 10
0.01 50 50 18 49 11 15 5 20 1.4 0.8 1.2 0.6 1.7 0.7 0.5 1.0
18 10 50 2.0 1.5 2.0 1.5 2.5 1.5 1.0 1.5
V s s s s s s s s s s
Gate On Time, Fixed Gate Off Time, Adjustable Gate Turn-On Delay, High-Side Gate Rise Time, High-Side Gate Turn-Off Delay, High-Side Gate Fall Time, High-Side Gate Turn-On Delay, Low-Side Gate Rise Time, Low-Side Gate Turn-Off Delay, Low-Side Gate Fall Time, Low-Side
Voltage remains low for time affected by CT.
Sense Differential > 70mV Sense Differential > 70mV, CT = 0pF Note 4 Note 5 Note 6 Note 7 Note 4 Note 8 Note 9 Note 10
When using sense MOSFETs, it is recommended that RSENSE < 50. Higher values may affect the sense MOSFET's current transfer ratio. DC measurement. Input switched from 0.8V (TTL low) to 2.0V (TTL high), time for Gate transition from 0V to 2V. Input switched from 0.8V (TTL low) to 2.0V (TTL high), time for Gate transition from 2V to 17V. Input switched from 2.0V (TTL high) to 0.8V (TTL low), time for Gate transition from 20V (Gate on voltage) to 17V. Input switched from 2.0V (TTL high) to 0.8V (TTL low), time for Gate transition from 17V to 2V. Input switched from 0.8V (TTL low) to 2.0V (TTL high), time for Gate transition from 2V to 10V. Input switched from 2.0V (TTL high) to 0.8V (TTL low), time for Gate transition from 15V (Gate on voltage) to 10V.
Note 10 Input switched from 2.0V (TTL high) to 0.8V (TTL low), time for Gate transition from 10V to 2V.
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Typical Characteristics
Supply Current vs. Supply Voltage
VIN = 0V 20 VGATE H (V) 15 10 5 0 tON 4V (S) 2.0 1.5 1.0 0.5 0.0
Gate to Source Voltage vs. Supply Voltage
25 2.5
Gate Turn-On Delay vs. Supply Voltage
6.0 5.5 5.0 ISUPPLY (mA) 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0
VGATE = VSUPPLY + 4V CL = CH = 1500pF CBOOST = 0.01F
NOTE: INCLUDES PROPAGATION DELAY & CROSS CONDUCTION LOCKOUT
VIN = 5V
5
10
15
20 25 30 VSUPPLY (V)
35
40
5
10
15
20 25 30 VSUPPLY (V)
35
40
5
10
15
20 25 30 VSUPPLY (V)
35
40
Gate Turn-On Delay vs. Supply Voltage
2.5 2 tON 10V (S) tON (S) 1.5 1 0.5 0 VGATE H = VSUPPLY + 10V CL = CH = 1500pF CBOOST = 0.01F
NOTE: INCLUDES PROPAGATION DELAY & CROSS CONDUCTION LOCKOUT
Gate Turn-On/Off Delay vs. Gate Capacitance
5.0 4.5 VGATE H = VSUPPLY + 4V 4.0 CL = CH VSUPPLY = 12V 3.5 3.0 HIGH-SIDE 2.5 2.0 1.5 1.0 0.5 PROP. DELAY
NOTE: INCLUDES PROPAGATION DELAY & CROSS CONDUCTION LOCKOUT
Gate Turn-On/Off Delay vs. Gate Capacitance
3.5 VGATE L = 4V 3.0 CL = CH VSUPPLY = 12V
tON (S)
2.5 LOW-SIDE 2.0 1.5
NOTE: INCLUDES PROPAGATION DELAY & CROSS CONDUCTION LOCKOUT
PROP. DELAY
5
10
15
20 25 30 VSUPPLY (V)
35
40
0.0 1x100 1x101 1x102 1x103 1x104 1x105 CGATE (pF)
1.0 1x100 1x101 1x102 1x103 1x104 1x105 CGATE (pF)
Overcurrent Retry Duty Cycle vs. Timing Capacitance
25 RETRY DUTY CYCLE (%) 20 15 10 5 0 0.1 NOTE: tON, tOFF TIME INDEPENDENT OF VSUPPLY 1 10 100 CTH (pF) 1000 10000 RETRY DUTY CYCLE (%) tON = 5S VSUPPLY = 12V HIGH SIDE
25.0 20.0 15.0 10.0
Overcurrent Retry Duty Cycle vs. Timing Capacitance
tON = 5S VSUPPLY = 12V
100 80
Input Current vs. Input Voltage
VSUPPLY = 12V
IIN (A)
LOW SIDE
60 40 20 0
5.0 0.0 0.1
1
10 100 CTL (pF)
1000 10000
0
5
10 15 VIN (V)
20
25
Sense Threshold vs. Temperature
80 70 VOLTAGE (mV) 60 50 40 30 20 -60 -30 0 30 60 90 120 150 TEMPERATURE (C)
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Input Enable Gate H Gate L Sense H+, H- Differential Sense L+, L- Differential Fault
TTL (H) 0V TTL (H) 0V 15V (max.) Source 15V (max.) 0V 50mV 0V 50mV 0V Off On
Timing Diagram 1. Normal Operation
5s
20s
Input Enable Gate H Gate L Sense H+, H- Differential Sense L+, L- Differential Fault
TTL (H) 0V TTL (H) 0V 15V (max.) 0V 15V (max.) 0V 50mV 0V 50mV 0V Off On
Timing Diagram 2. Overcurrent Fault with Retry
5s
Input Enable Gate H Gate L Sense H+, H- Differential Sense L+, L- Differential Fault
TTL (H) 0V TTL (H) 0V 15V (max.) Source 15V (max.) 0V 50mV 0V 50mV 0V Off On
Timing Diagram 3. Overcurrent Fault with Maintained Off September 1999 183 MIC5022
MIC5022
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Functional Description
Refer to the MIC5022 block diagram. Input A signal greater than 1.4V (nominal) applied to the MIC5022 INPUT causes gate enhancement on an external MOSFET connected to GATE H turning the high-side MOSFET on. At the same time internal logic removes gate enhancement from an external MOSFET connected to GATE L, turning the low-side MOSFET off. An internal pull-down resistor insures that an open INPUT remains low, keeping the external high-side MOSFET turned off and the low-side MOSFET turned on. Enable (Active Low) A signal greater than 1.4V (nominal) applied to the MIC5022 ENABLE keeps both GATE outputs off. An internal pull-down resistor insures that the MIC5022 is enabled if the pin is open. Gate Outputs Rapid rise and fall times on the GATE output are possible because each input state change triggers a one-shot which activates a high-value current sink (10I2) for a short time. This draws a high current though a current mirror circuit causing the output transistors to quickly charge or discharge the external FET's gate. A second current sink continuously draws the lower value of current used to maintain the gate voltage for the selected state. Internal 15V Zener diodes protect the external high-side and low-side MOSFETs by limiting the gate to source voltage. Charge Pump (High-Side) An internal charge pump utilizes an external "boost" capacitor connected between VBOOST and the source of the external FET (refer to Typical Application). The boost capacitor stores charge when the FET is off. As the FET begins to turn on the voltage on the source side of the capacitor increases (because it is on the high side of the load) raising the VBOOST pin voltage. The boost capacitor charge is directed through the gate pin to quickly charge the FET's gate to 15V maximum above VDD. The internal charge pump maintains the gate voltage by supplying a small current as needed. Overcurrent Limiting (High or Low-Side) Current source I1 charges CINT upon power up. An optional external capacitor connected to CT is kept discharged through a FET Q1. A fault condition (> 50mV from SENSE + to SENSE -) causes the overcurrent comparator to enable current sink 2I1 which overcomes current source I1 to discharge CINT in about 5s time. When CINT is discharged, the INPUT is disabled, the FAULT output is enabled, and CINT and CT are ready to be charged. Since the INPUT is disabled the GATE output turns off. When the GATE output turns off the FET, the overcurrent signal is removed from the sense inputs which deactivates current sink 2I1. This allows CINT and the optional capacitor connected to CT to recharge. A Schmitt trigger delays the retry while the capacitor(s) recharge. Retry delay is increased by connecting a capacitor connected to CT (optional). The MIC5022's low-side driver may be used without current sensing by grounding both SENSE + and SENSE - pins. The high-side driver may be used without current sensing by connecting SENSE + and SENSE - to the source of the external high-side MOSFET. Fault Output The FAULT output is an open collector transistor. FAULT is active at approximately the same time the output is disabled by a fault condition (5s after an overcurrent condition is sensed). The FAULT output is open circuit (off) during each successive retry (5s).
Typical Full-Bridge Application
+12V to +20V MIC5022 10F TTL Input (PWM signal) 1 2 3 4 5 6 7 VDD Input VBOOST Gate H 14 13 12 11 10 9 8 0.01F 0.01F Load 14 13 12 11 10 9 8 MIC5022 VBOOST Gate H VDD Input 1 2 3 4 5 6 7 10F TTL Input (PWM signal)
Fault Sense H- CTH Enable CTL Gnd Sense H+ Gate L Sense L- Sense L+
Sense H- Fault Sense H+ Gate L Sense L- Sense L+ CTH
Enable CTL Gnd
Figure 1. Basic Full-Bridge Circuit MIC5022 184 September 1999
MIC5022
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Applications Information
The MIC5022 MOSFET driver is designed for half-bridge switching applications where overcurrent limiting and high speed are required. The MIC5022 can control MOSFETs that switch voltages up to 36V. The MIC5022 functionally includes the MIC5020 and MIC5021 with additional circuitry to coordinate the operation of the high and low-side drivers. Since most output considerations are similar, refer to the MIC5020 and MIC5021 data sheets for additional applications information. Supply Voltage The MIC5022's supply input (VDD) is rated up to 36V. The supply voltage must be equal to or greater than the voltage applied to the drain of the external N-channel MOSFET. A 16V minimum supply is recommended to produce continuous on-state, gate drive voltage for standard MOSFETs (10V nominal gate enhancement). When the driver is powered from a 12V to 16V supply, a logiclevel MOSFET is recommended (5V nominal gate enhancement). PWM operation may produce satisfactory gate enhancement at lower supply voltages. This occurs when fast switching repetition makes the boost capacitor a more significant voltage supply than the internal charge pump. Overcurrent Limiting Separate high and low-side 50mV comparators are provided for current sensing. The low level trip point minimizes I2R losses when a power resistor 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 CT connection. CT to ground causes maintained gate drive shutdown following an overcurrent condition. CT open, or a capacitor to ground, causes automatic retry. The default duty cycle (CT open) is approximately 20% (the high side is slightly greater than the low side). Refer to the typical characteristics when selecting a capacitor for a reduced duty cycle. CT through a pull-up resistor to VDD increases the duty cycle. 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 MIC5022 may be damaged if the voltage applied to CT exceeds the absolute maximum voltage rating. Boost Capacitor Selection For 12V to 20V operation, the boost capacitor should be 0.01F; and for 12V to 36V operation, the boost capacitor should be 2.7nF; both connected between VBOOST and the MOSFET source. The preferred configuration for 20V to 36V operation is a 0.1F capacitor connected between VBOOST and VDD . Refer to the MIC5021 data sheet for examples. Do not connect capacitors between VBOOST and the MOSFET source and between VBOOST and VDD at the same time. Larger capacitors than specified may damage the MIC5022. September 1999 185 Circuits Without Current Sensing Current sensing may be omitted by connecting the high-side SENSE + and SENSE - pins to the source of the MOSFET or the supply and the low-side SENSE + and SENSE - pins to ground. Do not connect the high-side sense pins to ground. Inductive Load Precautions Circuits controlling inductive loads require precautions when controlled by the MIC5022. Wire wound resistors, which are sometimes used to simulate other loads, can also show significant inductive properties. Sense Pin Considerations The sense pins of the MIC5022 are sensitive to negative voltages. If a voltage spike is too negative (below approximately -0.5V), current will be drawn from functional sections of the IC resulting in unpredictable circuit behavior or damage. Resistors and Schottky diodes may be used to protect the sense pins from the negative spikes. Refer to the MIC5021 data sheet for details.
High-Side Sensing For the high-side driver, sensing the current on the supply side of the high-side MOSFET locates the SENSE pins away from the inductive spike. Refer to the MIC5021 data sheet for details. Low-Temperature Operation As the temperature of the MIC5022AJB (extended temperature range version--no longer available) approaches -55C, the driver's off-state, gate-output offset from ground increases. If the operating environment of the MIC5022AJB includes low temperatures (-40C to -55C), add an external 2.2M resistor from gate-to-source or from gate-to-ground. This assures that the driver's gate-to-source voltage is far below the external MOSFET's gate threshold voltage, forcing the MOSFET fully off. Refer to the MIC5020 and MIC5021 data sheets for examples. The gate-to-source configuration is appropriate for resistive and inductive loads. This also causes the smallest decrease in gate output voltage. The gate-to-ground configuration is appropriate for resistive, inductive, or capacitive loads. This configuration will decrease the gate output voltage slightly more than the gate-tosource configuration. Full-Bridge Motor Control An application for two MIC5022s is the full-bridge motor control circuit. Two high or two low-side sense inputs may be used for overcurrent detection. (Low-side sensing is shown in Figure 2). Sensing at four locations is usually unnecessary. When switching inductive loads, such as motors, it is desirable to place the high-side sense inputs on the supply side of the MOSFETs. The helps prevent the inductive spikes that occur upon load shutoff from affecting the sense inputs.
MIC5022
MIC5022
+12V to +20V MIC5022 10F TTL Input (PWM signal) 1 2 3 4 5 6 7 VDD Input VBOOST Gate H 14 13 12 11 10 9 8 RS1 RS2 0.01F M 0.01F 14 13 12 11 10 9 8 MIC5022 VBOOST Gate H VDD Input 1 2 3 4 5 6 7 10F TTL Input (PWM signal)
Micrel
Fault Sense H- CTH Enable CTL Gnd Sense H+ Gate L Sense L- Sense L+
Sense H- Fault Sense H+ Gate L Sense L- Sense L+ CTH
Enable CTL Gnd
Figure 2. Full-Bridge Motor Control Application
Synchronous Rectifier Converter The MIC5022 can be part of a synchronous rectifier in SMPS (switch mode power supply) applications. This circuit uses the MIC38C43 SMPS controller IC to switch a pass transistor (Q1) and a "synchronous rectifier" transistor (Q2) using the MIC5022. The MIC38C43 controller switches the transistors at 50kHz. Output regulation is maintained using PWM. When the pass transistor is on, the synchronous rectifier is off and current is
+12V
forced through the inductor to the output capacitor and load. When the pass transistor is switched off, the synchronous rectifier is switched on allowing current to continue to flow as the inductor returns stored energy. The synchronous rectifier MOSFET has a lower voltage drop than the forward voltage drop across a Schottky diode. This increases converter efficiency which extends battery life in portable equipment.
10k 13k 0.1F 47k 0.15F 300k MIC38C43 4.7nF 1 4.3k 2 3 3.3k 2200pF 10k 4 Comp FB IS RT/CT VREF VDD VOUT Gnd 8 8 7 9 6 7 5 470F 25V MIC5022 1 5 2 V+ Enable Input S L+ S L- Gnd Gate H 14 VPP Gate L 11 S H+ 12 S H- 3 Fault 10 Q2 1000F Low ESR 0.1F 13 Q1 5m 70H SMP06N06-14 VOUT 5V, 8A
Figure 3. 50kHz Synchronous Rectifier Converter
MIC5022
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September 1999

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