MIC5021 MICREL | Alldatasheet

Document overview

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Technical content

Features

  • 12V to 36V operation
  • 550ns rise/fall time driving 2000pF
  • TTL compatible input with internal pull-down resistor
  • Overcurrent limit
  • Gate to source protection
  • Internal charge pump
  • 100kHz operation guaranteed over full temperature and operating voltage range
  • Compatible with current sensing MOSFETs
  • Current source drive reduces EMI

Applications

  • Lamp control
  • Heater control
  • Motor control
  • Solenoid switching
  • Switch-mode power supplies
  • Circuit breaker General Description The MIC5021 high-side MOSFET driver is designed to oper- ate 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, SMPS (switch mode power supplies), and applications using IGBTs. The MIC5021 can also operate as a circuit breaker with or without automatic retry. A rising or falling edge on the input results in a current source pulse or sink pulse on the gate output. This output current pulse can turn on a 2000pF MOSFET in approximately 550ns. The MIC5021 then supplies a limited current (< 2mA), if necessary, to maintain the output state. An overcurrent comparator with a trip voltage of 50mV makes the MIC5021 ideal for use with a current sensing MOSFET. An external low value resistor may be used instead of a sensing MOSFET for more precise overcurrent control. An optional external capacitor placed from the C T pin to ground may be used to control the current shutdown duty cycle (dead time) from 20% to < 1%. A duty cycle from 20% to about 75% is possible with an optional pull-up resistor from C T to VDD . The MIC5021 is available in 8-pin SOIC and plastic DIP packages. Other members of the MIC502x family include the MIC5020 low-side driver and the MIC5022 half-bridge driver with a cross-conduction interlock. Typical Application VDD Input C T Gnd VBOOST Gate Sense Sense TTL Input R SENSE N-Channel Power MOSFET +12V to +36V MIC5021 10µF 2.7 nF Load R SENSE = 50mV ITRIP * increases time before retry optional* High-Side Driver with Overcurrent Trip and Retry

Pin Number Pin Name Pin Function 1V DD Supply: +12V to +36V. Decouple with ≥ 10µF capacitor. 2 Input TTL Compatible Input: Logic high turns the external MOSFET on. An internal pull-down returns an open pin to logic low. 3C T Retry Timing Capacitor: 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.
  • Pull-up resistor = approx. 20% to approx. 75% duty cycle.
  • Ground = maintained shutdown upon overcurrent condition.

4 Gnd Circuit Ground

5 Sense + 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.

6 Sense – Current Sense Comparator (–) Input: Connect to the low side of the sense

resistor (usually the high side of the load). 7 Gate 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 current. 8V BOOST Charge Pump Boost Capacitor: A bootstrap capacitor from VBOOST to the FET source pin supplies charge to quickly enhance the Gate output during turn-on. Pin Configuration VDD Input CT Gnd VBOOST Gate Sense− Sense+ VBOOST Gate Sense− Sense+ VDD Input CT Gnd Block Diagram Sense – Sense + 6V Internal Regulator C INT 2I1 50mV Input ONE- SHOT Gate C T OFF ON Fault Normal I210I2 15V CHARGE PUMP VDD VBOOST Transistor: 106 (N) (M)

Electrical Characteristics

TA = 25°C, Gnd = 0V, VDD = 12V, CT = Open, Gate CL = 1500pF (IRF540 MOSFET) unless otherwise specified Symbol Parameter Condition Min Typ Max Units D.C. Supply Current V DD = 12V, Input = 0V 1.8 4 mA VDD = 36V, Input = 0V 2.5 6 mA VDD = 12V, Input = 5V 1.7 4 mA VDD = 36V, Input = 5V 2.5 6 mA Input Threshold 0.8 1.4 2.0 V Input Hysteresis 0.1 V Input Pull-Down Current Input = 5V 10 20 40 µA Current Limit Threshold Note 1 30 50 70 mV Gate On Voltage V DD = 12V Note 2 16 18 21 V VDD = 36V Note 2 46 50 52 V tG(ON) Gate On Time, Fixed Sense Differential > 70mV 2 6 10 µs tG(OFF) Gate Off Time, Adjustable Sense Differential > 70mV, CT = 0pF 10 20 50 µs tDLH Gate Turn-On Delay Note 3 500 1000 ns tR Gate Rise Time Note 4 400 500 ns tDLH Gate Turn-Off Delay Note 5 800 1500 ns tF Gate Fall Time Note 6 400 500 ns fmax Maximum Operating Frequency Note 7 100 150 kHz Note 1 When using sense MOSFETs, it is recommended that RSENSE < 50Ω . Higher values may affect the sense MOSFET’s current transfer ratio. Note 2 DC measurement. Note 3 Input switched from 0.8V (TTL low) to 2.0V (TTL high), time for Gate transition from 0V to 2V. Note 4 Input switched from 0.8V (TTL low) to 2.0V (TTL high), time for Gate transition from 2V to 17V. Note 5 Input switched from 2.0V (TTL high) to 0.8V (TTL low), time for Gate transition from 20V (Gate on voltage) to 17V. Note 6 Input switched from 2.0V (TTL high) to 0.8V (TTL low), time for Gate transition from 17V to 2V. Note 7 Frequency where gate on voltage reduces to 17V with 50% input duty cycle. Absolute Maximum Ratings Operating Ratings Temperature Range

0.0 0.5 1.0 1.5 2.0 2.5 5 1 01 52 02 53 03 54 0 ISUPPLY (mA) VSUPPLY (V) Supply Current vs. Supply Voltage VIN = 0V VIN = 5V 650 700 750 800 850 900 5 1 01 52 02 53 03 54 0 tON 4V (ns) VSUPPLY (V) Gate Turn-On Delay vs. Supply Voltage VGATE =VSUPPLY + 4V C L = 1500pF (IRCZ34) C BOOST = 0.01µF INCLUDES PROPAGATION DELAY 750 800 850 900 950 1000 5 1 01 52 02 53 03 54 0 tON 10V (ns) VSUPPLY (V) Gate Turn-On Delay vs. Supply Voltage VGATE = VSUPPLY + 10V C L = 1500pF (IRCZ34) C BOOST = 0.01µF INCLUDES PROPAGATION DELAY 0.0 0.5 1.0 1.5 2.0 2.5 1x10 0 1x101 1x102 1x103 1x104 1x105 tON (µs) C GATE (pF) Gate Turn-On Delay vs. Gate Capacitance VGATE = VSUPPLY + 4V VSUPPLY = 12V INCLUDES PROPAGATION DELAY 750 1000 1250 1500 1750 2000 5 1 01 52 02 53 03 54 0 tOFF 4V (ns) VSUPPLY (V) Gate Turn-Off Delay vs. Supply Voltage VGATE =VSUPPLY + 4V R L = 400 INCLUDES PROPAGATION DELAY C GATE = 1500pF (IRCZ34) 0.1 1 10 100 1000 10000 RETRY DUTY CYCLE (%) C T (pF) NOTE: tON , tOFF TIME INDEPENDENT OF VSUPPLY Overcurrent Retry Duty Cycle vs. Timing Capacitance tON = 5µs VSUPPLY = 12V 5 1 01 52 02 53 03 54 0 VGATE (V) VSUPPLY (V) Gate Voltage Change vs. Supply Voltage VGATE = VGATE –VSUPPLY 100 0 5 10 15 20 25 IIN (µA) VIN (V) Input Current vs. Input Voltage VSUPPLY = 12V Typical Characteristics Timing Diagram 2. Fault Condition, CT = Open Timing Diagram 3. Fault Condition, C T = Grounded Input 0V TTL (H) Source 50mVSense +, – Differential Gate 15V (max.) 6µs 20µs Input 0V TTL (H) Source 50mVSense +, – Differential Gate 15V (max.) 6µs Input 0V TTL (H) Source 50mVSense +, – Differential Gate 15V (max.) Timing Diagram 1. Normal Operation -60 -30 0 30 60 90 120 150 VOLTAGE (mV) TEMPERATURE ( °C) Sense Threshold vs. Temperature

Refer to the MIC5021 block diagram. Input A signal greater than 1.4V (nominal) applied to the MIC5021 INPUT causes gate enhancement on an external MOSFET turning the MOSFET on. An internal pull-down resistor insures that an open INPUT remains low, keeping the external MOSFET turned off. Gate Output 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 (10I 2) 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 MOSFET’s gate. A second current sink continuously draws the lower value of current used to maintain the gate voltage for the selected state. An internal charge pump utilizes an external “boost” capacitor connected between V BOOST and the source of the external MOSFET. (Refer to typical application.) The boost capacitor stores charge when the MOSFET is off. As the MOSFET turns on, its source to ground voltage increases and is added to the voltage across the capacitor, raising the V BOOST pin voltage. The boost capacitor charge is directed through the GATE pin to quickly charge the MOSFET’s gate to 16V maximum above VDD . The internal charge pump maintains the gate voltage. An internal zener diode protects the external MOSFET by limiting the gate to source voltage. Sense Inputs The MIC5021’s 50mV (nominal) trip voltage is created by internal current sources that force approximately 5µA out of SENSE + and approximately 15µA (at trip) out of SENSE –. When SENSE – is 50mV or more below SENSE +, SENSE – steals base current from an internal drive transistor shutting off the external MOSFET. Overcurrent Limiting Current source I 1 charges CINT upon power up. An optional external capacitor connected to CT is kept discharged through a MOSFET 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 a short time. When C INT is discharged, the INPUT is disabled, which turns off the gate output, and CINT and CT are ready to be charged. When the gate output turns the MOSFET off, the overcurrent signal is removed from the sense inputs which deactivates current sink 2I 1. 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 in- creased by connecting a capacitor to C T (optional). The retry cycle will continue until the fault is removed or the input is changed to TTL low. If CT is connected to ground, the circuit will not retry upon a fault condition. Supply Voltage The MIC5021’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 continu- ous on-state, gate drive voltage for standard MOSFETs (10V nominal gate enhancement). When the driver is powered from a 12V to 16V supply, a logic- level MOSFET is recommended (5V nominal gate enhance- ment). 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. Applications Information The MIC5021 MOSFET driver is intended for high-side switching applications where overcurrent limiting and high speed are required. The MIC5021 can control MOSFETs that switch voltages up to 36V. High-Side Switch Circuit Advantages High-side switching allows more of the load related compo- nents and wiring to remain near ground potential when compared to low-side switching. This reduces the chances of short-to-ground accidents or failures. Speed Advantage The MIC5021 is about two orders of magnitude faster than the low cost MIC5014 making it suitable for high-frequency high-efficiency circuit operation in PWM (pulse width modu- lation) designs used for motor control, SMPS (switch mode power supply) and heating element control. Switched loads (on/off) benefit from the MIC5021’s fast switching times by allowing use of MOSFETs with smaller safe operating areas. (Larger MOSFETs are often required when using slower drivers.)