MIC5021 Micrel

MIC5021
High-Speed High-Side MOSFET Driver

General Description Features

The MIC5021 high-side MOSFET driver is designed to oper- • 12V to 36V operation
ate at frequencies up to 100kHz (5kHz PWM for 2% to 100% • 550ns rise/fall time driving 2000pF
duty cycle) and is an ideal choice for high speed applications • TTL compatible input with internal pull-down resistor
such as motor control, SMPS (switch mode power supplies), • Overcurrent limit
and applications using IGBTs. The MIC5021 can also • Gate to source protection
operate as a circuit breaker with or without automatic retry. • Internal charge pump
A rising or falling edge on the input results in a current source • 100kHz operation guaranteed over full temperature and
pulse or sink pulse on the gate output. This output current operating voltage range
pulse can turn on a 2000pF MOSFET in approximately • Compatible with current sensing MOSFETs
550ns. The MIC5021 then supplies a limited current (< 2mA), • Current source drive reduces EMI
if necessary, to maintain the output state. Applications
An overcurrent comparator with a trip voltage of 50mV makes • Lamp control
the MIC5021 ideal for use with a current sensing MOSFET. • Heater control
An external low value resistor may be used instead of a • Motor control
sensing MOSFET for more precise overcurrent control. An • Solenoid switching
optional external capacitor placed from the CT pin to ground • Switch-mode power supplies
may be used to control the current shutdown duty cycle (dead • Circuit breaker
time) from 20% to < 1%. A duty cycle from 20% to about 75%
is possible with an optional pull-up resistor from CT to VDD. Ordering Information
The MIC5021 is available in 8-pin SOIC and plastic DIP 5
Part Number Temperature Range Package
packages.
MIC5021BM –40°C to +85°C 8-pin SOIC
Other members of the MIC502x family include the MIC5020
low-side driver and the MIC5022 half-bridge driver with a MIC5021BN –40°C to +85°C 8-pin Plastic DIP
cross-conduction interlock.

Typical Application
+12V to +36V

MIC5021
10µF 1 8
VDD VBOOST
2 7 N-Channel
TTL Input Input Gate
Power MOSFET
3 6
CT Sense
optional* 2.7
4 5 nF
Gnd Sense
RSENSE

RSENSE = 50mV
ITRIP
Load

* increases time before retry

High-Side Driver with Overcurrent Trip and Retry

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MIC5021 Micrel
Pin Configuration
1 VDD VBOOST 8 1 VDD VBOOST 8

2 Input Gate 7 2 Input Gate 7

3 CT Sense− 6 3 CT Sense− 6
4 Gnd Sense+ 5 4 Gnd Sense+ 5

DIP Package SOIC Package

(N) (M)

Block Diagram 6V Internal Regulator

I1
Fault
CT
CINT Normal VDD
2I1
CHARGE VBOOST
Q1 PUMP

Sense + 15V
Sense –
ON
50mV
OFF
6V
↑ ONE-
10I2 I2 Gate
Input ↓ SHOT

Transistor: 106

Pin Description
Pin Number Pin Name Pin Function
1 VDD 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.
3 CT 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
RSENSE 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 VGS
to 15V max. to prevent Gate-to-Source damage. Will sink and source
current.
8 VBOOST 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.

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MIC5021 Micrel
Absolute Maximum Ratings Operating Ratings
Supply Voltage (VDD) .................................................. +40V Supply Voltage (VDD) .................................... +12V to +36V
Input Voltage ................................................ –0.5V to +15V Temperature Range
Sense Differential Voltage .......................................... ±6.5V PDIP ....................................................... –40°C to +85°C
Sense + or Sense – to Gnd .......................... –0.5V to +36V SOIC ...................................................... –40°C to +85°C
Timer Voltage (CT) ..................................................... +5.5V
VBOOST Capacitor .................................................... 0.01µF

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 VDD = 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 VDD = 12V Note 2 16 18 21 V
VDD = 36V Note 2 46 50 52 V
5
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.

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MIC5021 Micrel
Typical Characteristics

Supply Current vs. Gate Voltage Change Gate Turn-On Delay vs.
Supply Voltage vs. Supply Voltage Supply Voltage
2.5 25 900
VGATE = VGATE – VSUPPLY VGATE = VSUPPLY + 4V
2.0 VIN = 0V 20 850 CL = 1500pF (IRCZ34)
CBOOST = 0.01µF
ISUPPLY (mA)

tON 4V (ns)
VGATE (V)
1.5 15 800
VIN = 5V

1.0 10 750
INCLUDES PROPAGATION DELAY
0.5 5 700

0.0 0 650
5 10 15 20 25 30 35 40 5 10 15 20 25 30 35 40 5 10 15 20 25 30 35 40
VSUPPLY (V) VSUPPLY (V) VSUPPLY (V)

Gate Turn-On Delay vs. Gate Turn-On Delay vs. Gate Turn-Off Delay vs.
Supply Voltage Gate Capacitance Supply Voltage
1000 2.5 2000
VGATE = VSUPPLY + 10V VGATE = VSUPPLY + 4V VGATE = VSUPPLY + 4V
CL = 1500pF (IRCZ34) VSUPPLY = 12V RL = 400
950 2.0 1750
CBOOST = 0.01µF
tON 10V (ns)

tOFF 4V (ns)
900 1.5 1500
tON (µs)

850 1.0 1250 CGATE = 1500pF

(IRCZ34)
800 0.5 1000
INCLUDES PROPAGATION DELAY INCLUDES PROPAGATION DELAY
INCLUDES PROPAGATION DELAY
750 0.0 750
5 10 15 20 25 30 35 40 1x100 1x101 1x102 1x103 1x104 1x105 5 10 15 20 25 30 35 40
VSUPPLY (V) CGATE (pF) VSUPPLY (V)

Overcurrent Retry Duty Input Current vs. Sense Threshold vs.

Cycle vs. Timing Capacitance Input Voltage Temperature
25 100 80
tON = 5µs VSUPPLY = 12V
RETRY DUTY CYCLE (%)

20 VSUPPLY = 12V 80 70
VOLTAGE (mV)

60
15 60
IIN (µA)

50
10 NOTE: 40
tON, tOFF TIME 40

5 INDEPENDENT 20
OF VSUPPLY 30

0 0 20
0.1 1 10 100 1000 10000 0 5 10 15 20 25 -60 -30 0 30 60 90 120 150
CT (pF) VIN (V) TEMPERATURE (°C)

TTL (H)
Input 0V

15V (max.)
Gate
Source
Sense +, – 50mV
Differential 0V

Timing Diagram 1. Normal Operation

6µs 20µs 6µs
TTL (H) TTL (H)
Input 0V
Input 0V
15V (max.) 15V (max.)
Gate Gate
Source Source
Sense +, – 50mV Sense +, – 50mV
Differential 0V Differential 0V

Timing Diagram 2. Fault Condition, CT = Open Timing Diagram 3. Fault Condition, CT = Grounded

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MIC5021 Micrel
Functional Description An internal zener diode protects the external MOSFET by
limiting the gate to source voltage.
Refer to the MIC5021 block diagram.
Sense Inputs
Input
The MIC5021’s 50mV (nominal) trip voltage is created by
A signal greater than 1.4V (nominal) applied to the MIC5021
internal current sources that force approximately 5µA out of
INPUT causes gate enhancement on an external MOSFET
SENSE + and approximately 15µA (at trip) out of SENSE –.
turning the MOSFET on.
When SENSE – is 50mV or more below SENSE +, SENSE –
An internal pull-down resistor insures that an open INPUT steals base current from an internal drive transistor shutting
remains low, keeping the external MOSFET turned off. off the external MOSFET.
Gate Output Overcurrent Limiting
Rapid rise and fall times on the GATE output are possible Current source I1 charges CINT upon power up. An optional
because each input state change triggers a one-shot which external capacitor connected to CT is kept discharged through
activates a high-value current sink (10I2) for a short time. This a MOSFET Q1.
draws a high current though a current mirror circuit causing
A fault condition (> 50mV from SENSE + to SENSE –) causes
the output transistors to quickly charge or discharge the
the overcurrent comparator to enable current sink 2I1 which
external MOSFET’s gate.
overcomes current source I1 to discharge CINT in a short time.
A second current sink continuously draws the lower value of When CINT is discharged, the INPUT is disabled, which turns
current used to maintain the gate voltage for the selected off the gate output, and CINT and CT are ready to be charged.
state.
When the gate output turns the MOSFET off, the overcurrent
An internal charge pump utilizes an external “boost” capacitor signal is removed from the sense inputs which deactivates
connected between VBOOST and the source of the external current sink 2I1. This allows CINT and the optional capacitor
MOSFET. (Refer to typical application.) The boost capacitor connected to CT to recharge. A Schmitt trigger delays the
stores charge when the MOSFET is off. As the MOSFET retry while the capacitor(s) recharge. Retry delay is in-
turns on, its source to ground voltage increases and is added creased by connecting a capacitor to CT (optional).
to the voltage across the capacitor, raising the VBOOST pin
The retry cycle will continue until the fault is removed or the
voltage. The boost capacitor charge is directed through the
input is changed to TTL low.
GATE pin to quickly charge the MOSFET’s gate to 16V
maximum above VDD. The internal charge pump maintains If CT is connected to ground, the circuit will not retry upon a 5
the gate voltage. fault condition.

Applications Information Supply Voltage

The MIC5021 MOSFET driver is intended for high-side The MIC5021’s supply input (VDD) is rated up to 36V. The
switching applications where overcurrent limiting and high supply voltage must be equal to or greater than the voltage
speed are required. The MIC5021 can control MOSFETs that applied to the drain of the external N-channel MOSFET.
switch voltages up to 36V. A 16V minimum supply is recommended to produce continu-
High-Side Switch Circuit Advantages ous on-state, gate drive voltage for standard MOSFETs (10V
nominal gate enhancement).
High-side switching allows more of the load related compo-
nents and wiring to remain near ground potential when When the driver is powered from a 12V to 16V supply, a logic-
compared to low-side switching. This reduces the chances level MOSFET is recommended (5V nominal gate enhance-
of short-to-ground accidents or failures. ment).
Speed Advantage PWM operation may produce satisfactory gate enhancement
at lower supply voltages. This occurs when fast switching
The MIC5021 is about two orders of magnitude faster than
repetition makes the boost capacitor a more significant
the low cost MIC5014 making it suitable for high-frequency
voltage supply than the internal charge pump.
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.)

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MIC5021 Micrel
Logic-Level MOSFET Precautions A 0.01µF boost capacitor is recommended for best perfor-
Logic-level MOSFETs have lower maximum gate-to-source mance in the 12V to 20V range. Refer to figure 1. Larger
voltage ratings (typically ±10V) than standard MOSFETs capacitors may damage the MIC5021.
(typically ±20V). When an external MOSFET is turned on, the +12V to +36V
doubling effect of the boost capacitor can cause the gate-to-
source voltage to momentarily exceed 10V. Internal zener MIC5021
diodes clamp this voltage to 16V maximum which is too high 10µF 1 8
VDD VBOOST
for logic-level MOSFETs. To protect logic-level MOSFETs, TTL Input
2 7
Input Gate
connect a zener diode (5V≤VZener<10V) from gate to source. 3 6
CT Sense 2.7
nF
Overcurrent Limiting 4 5
Gnd Sense
A 50mV comparator is provided for current sensing. The low
level trip point minimizes I2R losses when a power resistor is
used for current sensing.

Load
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 maintains gate drive shutdown following an Figure 2. 12V to 36V Configuration
overcurrent condition.
If the full 12V to 36V voltage range is required, the boost
CT open, or a capacitor to ground, causes automatic retry. capacitor value must be reduced to 2.7nF. Refer to Figure 2.
The default duty cycle (CT open) is approximately 20%. Refer The recommended configuration for the 20V to 36V range is
to the electrical characteristics when selecting a capacitor for to place the capacitor is placed between VDD and VBOOST as
reduced duty cycle. shown in Figure 3.
CT through a pull-up resistor to VDD increases the duty cycle. +12V to +36V
Increasing the duty cycle increases the power dissipation in
the load and MOSFET under a “fault” condition. Circuits may 0.1
MIC5021
become unstable at a duty cycle of about 75% or higher, 10µF 1 8 µF
VDD VBOOST
depending on conditions. Caution: The MIC5021 may be 2 7
damaged if the voltage applied to CT exceeds the absolute TTL Input Input Gate
3 6
maximum voltage rating. CT Sense
4 5
Boost Capacitor Selection Gnd Sense

The boost capacitor value will vary depending on the supply

voltage range.
+12V to +20V

Load
MIC5021
10µF 1 8
VDD VBOOST

TTL Input
2
Input Gate
7 Figure 3. Preferred 20V to 36V Configuration
3
CT
6
0.01 Do not use both boost capacitor between VBOOST and the
Sense
µF MOSFET source and VBOOST and VDD at the same time.
4 5
Gnd Sense
Current Sense Resistors
Lead length can be significant when using low value (< 1Ω)
resistors for current sensing. Errors caused by lead length
Load

can be avoided by using four-teminal current sensing resis-

tors. Four-terminal resistors are available from several
manufacturers.
Figure 1. 12V to 20V Configuration

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MIC5021 Micrel
Circuits Without Current Sensing The diode should have a peak forward current rating greater
V+ than the load current. This is because the current through the
diode is the same as the load current at the instant the
MOSFET is turned off.
MIC5021
10µF 1 8 +20V to +36V
VDD VBOOST
2 7 (+24V)
TTL Input Input Gate N-Channel
Power MOSFET 0.01
3 6 MIC5021
CT Sense− 1 8 µF
0.01 10µF VDD VBOOST
4 5 µF
Gnd Sense+ 2 7
TTL Input Input Gate N-Channel
Load Power MOSFET
3 6 (IRF540)
CT Sense
4 5
Gnd Sense
Figure 4a. Connecting Sense to Source RSENSE
(< 0.08Ω)
V+

Solenoid Schottky
MIC5021 (24V, 47Ω) Diode
10µF 1 8 (1N5822)
VDD VBOOST
2 7 N-Channel
TTL Input Input Gate
Power MOSFET
3 6
CT Sense− 0.01 Figure 5. Solenoid Driver
4 5 µF
Gnd Sense+ with Current Sensing
Load Sense Pin Considerations
The sense pins of the MIC5021 are sensitive to negative
Figure 4b. Connecting Sense to Supply voltages. Forcing the sense pins much below –0.5V effec-
Current sensing may be omitted by connecting the SENSE + tively reverses the supply voltage on portions of the driver
and SENSE – pins to the source of the MOSFET or to the resulting in unpredictable operation or damage.
supply. Connecting the SENSE pins to the supply is preferred MIC5021
1 8
for inductive loads. Do not connect the SENSE pins to ground.
2
VDD
7
5
Inductive Load Precautions Input Gate
MOSFET
3 6 Turnoff
Circuits controlling inductive loads, such as solenoids (Figure CT ~VDD
4 5
5) and motors, require precautions when controlled by the 0V

MIC5021. Wire wound resistors, which are sometimes used Negative

Spike

to simulate other loads, can also show significant inductive Forward drop across diodes
properties. allows leads to go negative. Inductive
Load
Current flows from ground (0V)
An inductive load releases stored energy when its current through the diodes to the load
flow is interrupted (when the MOSFET is switched off). The during negative transcients.
voltage across the inductor reverses and the inductor at- Figure 6. Inductive Load Turnoff
tempts to force current flow. Since the circuit appears open
Figure 6 shows current flowing out of the sense leads of an
(the MOSFET appears as a very high resistance) a very large
MIC5021 during a negative transient (inductive kick). Internal
negative voltage occurs across the inductor.
Schottky diodes attempt to limit the negative transient by
Limiting Inductive Spikes maintaining a low forward drop.
The voltage across the inductor can be limited by connecting Although the internal Schottky diodes can protect the driver
a Schottky diode across the load. The diode is forward biased in low-current resistive applications, they are inadequate for
only when the load is switched off. The Schottky diode inductive loads or the lead inductance in high-current resis-
clamps negative transients to a few volts. This protects the tive loads. Because of their small size, the diodes’ forward
MOSFET from drain-to-source breakdown and prevents the voltage drop quickly exceeds 0.5V as current increases.
transient from damaging the charge pump by way of the boost
capacitor. Also see Sense Pin Considerations below.

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MIC5021 Micrel
External Protection High-Side Sensing
Resistors placed in series with each SENSE connection limit Sensing the current on the high side of the MOSFET isolates
the current drawn from the internal Schottky diodes during a the SENSE pins from the inductive spike.
negative transient. This minimizes the forward drop across +12V to +20V
the diodes. (+12V)

MIC5021 MIC5021
1 8 1 8 RSENSE
VDD VBOOST 10µF VDD VBOOST (< 0.01Ω)
2 7 2 7
Input Gate N-Channel TTL Input N-Channel
Power MOSFET Input Gate
3 6 Power MOSFET
CT 3 6 (IRFZ44)
Sense− CT Sense
4 5 R1 4 5
Gnd Sense+ Gnd Sense
5µA 0.01
VR1 RS 50mV nominal
(at trip) µF
R2 Wirewound
VR1 = VR2 Resistor
to avoid skewing 15µA (3Ω)
the 50mV trip point.. VR2
Load

(5mV suggested)

R1 ≅ 3 × R2
Figure 9. High Side Sensing
Figure 7. Resistor Voltage Drop
Lamp Driver Application
During normal operation, sensing current from the sense pins
Incandescent lamps have a high inrush current (low resis-
is unequal (5µA and 15µA). The internal Schottky diodes are
tance) when turned on. The MIC5021 can perform a “soft
reverse biased and have no effect. To avoid skewing the trip
start” by pulsing the MOSFET (overcurrent condition) until
voltage, the current limiting resistors must drop equal volt-
the filament is warm and its current decreases (resistance
ages at the trip point currents. See Figure 7. To minimize
increases). The sense resistor value is selected so the
resistor tolerance error, use a voltage drop lower than the trip
voltage drop across the sense resistor decreases below the
voltage of 50mV. 5mV is suggested.
sense threshold (50mV) as the filament becomes warm. The
External Schottky diodes are also recommended. See D2 FET is no longer pulsed and the lamp turns completely on.
and D3 in Figure 8. The external diodes clamp negative
V+
transients better than the internal diodes because their larger
size minimizes the forward voltage drop at higher currents. (+12V)

+12V to +36V MIC5021

10µF 1 8
VDD VBOOST
2 7
TTL Input Input Gate N-Channel
MIC5021 Power MOSFET
1 8 3 6 (IRF540)
10µF VDD VBOOST CT Sense− 0.01
2 7 4 5 µF
TTL Input Input Gate N-Channel Gnd Sense+
2.7 Power MOSFET
3 6 RSENSE
CT Sense nF (0.041Ω)
4 5 R1
Gnd Sense
1.0k "( )" values apply to demo circuit. Incandescent
D2 RSENSE Lamp (#1157)
11DQ03 See text.
R2
D3 330Ω
11DQ03
Figure 10. Lamp Driver with
Inductive Current Sensing
D1 Load
A lamp may not fully turn on if the filament does not heat up
adequately. Changing the duty cycle, sense resistor, or both
to match the filament characteristics can correct the problem.
Figure 8. Protection from Inductive Kick Soft start can be demonstrated using a #1157 dual filament
automotive lamp. The value of RS shown in Figure 10 allows
for soft start of the higher-resistance filament (measures
approx. 2.1Ω cold or 21Ω hot).

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MIC5021 Micrel
Remote Overcurrent Limiting Reset +12V to +36V

In circuit breaker applications where the MIC5021 maintains

an off condition after an overcurrent condition is sensed, the MIC5021AJB
10µF 1 8
CT pin can be used to reset the MIC5021. VDD VBOOST
2 7
+12V to +20V TTL Input Input Gate
3 6
CT Sense 2.7
4 5 nF 2.2M
MIC5021 Gnd Sense
10µF 1 8
VDD VBOOST RSENSE
2 7
TTL Input Input Gate N-Channel
Power add resistor for
10k to 3 6 MOSFET –40°C to –55°C
100k CT Sense operation

Load
2N3904 0.01
Q1 4 5 µF
74HC04 Gnd Sense
(example) RSENSE

Retry (H)
Maintained (L)
Figure 12a. Gate-to-Source Pull Down

Load
The gate-to-source configuration (refer to Figure 12a) is
appropriate for resistive and inductive loads. This also
causes the smallest decrease in gate output voltage.
Figure 11. Remote Control Circuit +12V to +36V

Switching Q1 on pulls CT low which keeps the MIC5021 GATE

output off when an overcurrent is sensed. Switching Q1 off MIC5021AJB
10µF 1 8
causes CT to appear open. The MIC5021 retries in about VDD VBOOST
20µs and continues to retry until the overcurrent condition is 2 7
TTL Input Input Gate
removed. 3
CT
6
Sense 2.7
For demonstration purposes, a 680Ω load resistor and 3Ω 4
Gnd
5 nF
Sense
sense resistor will produce an overcurrent condition when the RSENSE
load’s supply (V+) is approximately 12V or greater.
5
Low-Temperature Operation
add resistor for

Load
As the temperature of the MIC5021AJB (extended tempera- –40°C to –55°C 2.2M
operation
ture range version—no longer available) approaches –55°C,
the driver’s off-state, gate-output offset from ground in-
creases. If the operating environment of the MIC5021AJB Figure 12b. Gate-to-Ground Pull Down
includes low temperatures (–40°C to –55°C), add an external
2.2MΩ resistor as shown in Figures 12a or 12b. This assures The gate-to-ground configuration (refer to Figure 12b) is
that the driver’s gate-to-source voltage is far below the appropriate for resistive, inductive, or capacitive loads. This
external MOSFET’s gate threshold voltage, forcing the configuration will decrease the gate output voltage slightly
MOSFET fully off. more than the circuit shown in Figure 12a.

October 1998 5-177