MIC5031
Micrel
MIC5031
High-Speed High-Side MOSFET Driver
Not Recommended for New Designs
General Description
The MIC5031 MOSFET driver is designed to switch an
N-channel enhancement-type MOSFET from a TTL control
signal in a high-side switch application. The MIC5031 pro-
vides overcurrent protection, can accommodate loads with
high-inrush current, and is designed to survive automotive
power disturbances. This driver is suitable for up to 30kHz
PWM operation with 0% to 100% duty cycle.
The MIC5031 is powered by the +4.5V to +30V load voltage.
An external bootstrap capacitor and internal charge pump
drive the gate output higher than the supply voltage. The
bootstrap capacitor provides speed, while the charge pump
can sustain the high gate output voltage continuously.
The MIC5031 features a resistor programmable overcurrent
shutdown (circuit breaker) function that monitors the voltage
drop across the external MOSFET. A capacitor program-
mable shutdown delay allows a high-inrush current load to be
energized without causing undesired shutdown. An open-
load detection feature is included and can be used by adding
an external high-value resistor.
The MIC5031 is protected against automotive load dump and
reverse battery conditions. The driver is also protected from
excessive power dissipation by an internal overtemperature
shutdown circuit.
An open-collector fault flag output indicates overcurrent,
overtemperature, or open-load fault conditions.
Features
• +4.5V to +30V operation
• Fast gate drive
(rise time = 70ns, fall time = 50ns,
with 1000pF load and 5V supply)
• Overcurrent detection across MOSFET
• Overcurrent shutdown delay
• Charge pump for high-side dc applications
• TTL compatible input
• Overtemperature shutdown
• Automotive load dump protection
• Reverse battery protection
• Open-collector fault flag
• Near zero-current disable state
Applications
•
•
•
•
Automotive power switch
Automotive PWM control
Circuit breaker
PWM circuits
Ordering Information
Part Number
MIC5031BM
Temperature Range
–40°C to +85°C
Package
16-lead SOIC
Typical Application
+4.5V to +30V
100µF
100nF
10k
§
0.01µF
§
Enable
Disable
On
Off
4
3
10
8
11
9
5
51k
MIC5031
7
VDD
EN
CTL
CP1+
CP1–
CP2+
CP2–
GND
FLG
RV
G
CB
S
RI
CS
DLY
1
14
16
12
13
15
6
2
Normal
Fault
1k*
IRF540
0.1µF
100k
†
0.01µF
0.01µF
0.1µF
50pF
‡
12k* M
2N5822
15µF
* Sets Overcurrent Trip to MOSFET V
DS
≈
102mV
†
Optional Resistor for Open-Load Detection
‡
Optional Capacitor for Overcurrent Delay
§
Optional Resistor and Capacitor for Power-up Sequence
High-Side Power Switch and Circuit Breaker
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
August 1999
1
MIC5031
MIC5031
Micrel
Pin Configuration
FLG 1
DLY 2
CTL 3
EN 4
GND 5
CS 6
VDD 7
CP1– 8
16 G
15 RI
14 RV
13 S
12 CB
11 CP2+
10 CP1+
9 CP2–
16-lead SOIC (M)
Pin Description
Pin Number
1
2
3
Pin Name
FLG
DLY
CTL
Pin Function
Fault Flag: (Output): Open-collector output sinks current upon overcurrent,
open-load, or overtemperature detection. 10mA maximum load.
Overcurrent Delay Time Capacitor: Optional. Capacitor to ground delays
activation of overcurrent shutdown.
Control (Input): TTL compatible on/off control input. Logic high drives the
gate output above the supply voltage. Logic low forces the gate output near
ground. Logic low also resets the overcurrent fault latch.
Enable (Input): CMOS compatible input. Logic high enables the charge
pump. Logic low disables the charge pump and draws near zero supply
current.
Ground: Power return.
Internal Supply Storage Capacitor: 10µF external capacitor to GND.
Provides additional current to internal circuitry during switching transitions.
Supply (Input): +4.5V to +30V supply.
Charge Pump Capacitor #1: Refer to CP1+.
Charge Pump Capacitor #2: Refer to CP2+.
Charge Pump Capacitor #1: External 0.01µF voltage tripler capacitor.
Charge Pump Capacitor #2: External 0.01µF voltage tripler capacitor.
Bootstrap Capacitor: 0.1µF capacitor to source for fastest rise time.
Source: Source connection to external MOSFET.
Reference Voltage Resistor: Resistor to VDD provides a reference voltage
drop. A voltage drop across the external MOSFET that is greater than the
voltage drop across the reference resistor indicates an overcurrent condition.
(Refer
to applications section)
Zero temperature coefficient resistor
recommended.
Reference Current Resistor: Resistor to GND sets constant current value
through RV resistor (Refer
to applications section)
and matches tempera-
ture compensation of RV resistor. Zero temperature coefficient resistor
recommended.
Gate (Output) : Gate connection to external MOSFET.
4
EN
5
6
7
8
9
10
11
12
13
14
GND
CS
VDD
CP1–
CP2–
CP1+
CP2+
CB
S
RV
15
RI
16
G
MIC5031
2
August 1999
MIC5031
Micrel
Absolute Maximum Ratings
Supply Voltage (V
DD
) .................................................. +36V
Enable Input Voltage (V
EN
) ......................................... +36V
Control Input Voltage (V
CTL
)
V
DD
≤
15V ..................................................................V
DD
V
DD
> 15V ............................................................... +15V
Flag Output Voltage (V
FLG
) ......................................... +36V
Reference Voltage Input (V
RV
) .................................... +36V
Junction Temperature (T
J
) ........................................ 150°C
Operating Ratings
Supply Voltage (V
DD
) ................................... +4.5V to +30V
Ambient Temperature Range (T
A
)
A-temperature range ............................ –55°C to +125°C
B-temperature range .............................. –40°C to +85°C
Package Thermal Resistance (θ
JA
)
SOIC ................................................................. 115°C/W
Electrical Characteristics
V
DD
= 12V; C
B
= 0.1µF, CP1 = CP2 = 0.01µF; T
A
= 25°C; unless noted
Symbol
I
DD
Parameter
Supply current
Condition
V
EN
= 0V, V
CTL
= 0V
V
EN
= 12V, V
CTL
= 0V
V
EN
= 12V, V
CTL
= 5V
I
DDR
V
CTL
V
CTLH
I
CTL
V
EN
I
EN
V
IOS
I
RV
t
SHDL
V
G
t
DLR
t
R
t
DLF
t
F
V
OLTH
T
OT
T
OTH
f
CP
V
FLG
Note 1:
Min
Typ
0.3
1.0
0.72
–0.2
1.55
Max
3
Units
µA
mA
mA
µA
V
Reverse voltage leakage current
Control input voltage threshold
Control input voltage hysteresis
Control input current
Enable input voltage threshold
Enable input current
Overcurrent comparator offset
Current limit reference current
Overcurrent shut down delay
Gate drive voltage
Gate turn-on delay
Gate rise time
Gate turnoff delay
Gate fall time
Open-load threshold voltage
Overtemperature shut down
Overtemp. shut down hysteresis
Charge pump frequency
Flag active voltage
Oscillator burst mode at V
DD
≥
5.2V.
V
DD
= –12V
0.2
–5
0.5
0.1
6
0.1
1.0
1
V
µA
V
µA
mV
µA
µs
V
ns
ns
ns
ns
V
°C
°C
1
±5
R
RI
= 12.0k
C
DLY
= 50pF
V
EN
= 12V, V
CTL
= 5V
V
EN
= 12V, C
L
= 1000p
C
L
= 1000pF
C
L
= 1000pF
C
L
= 1000pF
V
EN
= 12V, V
CTL
= 0V
V
EN
= 12V, V
CTL
= 5V
V
EN
= 12V, V
CTL
= 5V
V
DD
= 5V,
Note 1
open load error, I
FLG
= 2mA (sink)
97
100
16
25
420
90
300
50
6.3
140
103
10
190
0.2
kHz
V
General Note:
Devices are ESD protected; however, handling precautions are recommended.
August 1999
3
MIC5031
MIC5031
Micrel
Block Diagram
V
SUPPLY
C1
CP1– CP1+
C2
CP2– CP1+
VDD
Charge Pump
CS
Bias
Regulator
Oscillator
Voltage
Tripler
Osc. Disable
Gate
Driver
G
Reset
CTL
(TTL)
Gate Drive
Regulator
CB
C3
External
N-Channel
MOSFET
Open-Load
Detect
Resistor
(Optional)
Logic
Open-Load Detect
EN
(CMOS)
S
Current Limit
Delay
Voltage
Comp.
RV
R1
DLY
Overcurrent
Delay
Capacitor
(Optional)
1.23V
Bandgap
Reference
Ref.
Current
Amp.
Lockout
Latch
RI
C4
R2
FLAG
Overtemp.
Detect
MIC5031
GND
MIC5031 with External Components
MIC5031
4
Inductive Load
August 1999
MIC5031
Micrel
Current Sense
Refer to the “Voltage Reference (Simplified)” diagram.
The MIC5031 detects an overcurrent condition by comparing
the voltage drop across the external MOSFET to a reference
voltage drop created across R1. If V
DS
exceeds V
R1
, a
comparator (not shown) shuts off the external MOSFET by
way of the current limit delay, lockout latch, and logic.
The bandgap reference, op amp and NPN create a constant
voltage (1.23V) across R2. This results in a constant current,
I
R2
, through R2. Ignoring a small amount of base current, the
same current (I
R2
) flows through R1. R1 is selected to
achieve the desired reference voltage drop, V
R1
. Refer to the
applications section for formulas.
Supply
Functional Description
Refer to “Functional Diagram.”
The MIC5031 is a noninverting device. Applying a CMOS
logic high signal to EN (enable input) activates the driver’s
internal circuitry. Applying a TTL logic high signal to CTL
(control input) produces gate drive output. The G (gate)
output is used to turn on an external N-channel MOSFET.
Control
CTL (control) is a TTL compatible input. The threshold is
approximately 1.4V, independent of the supply voltage.
The falling edge of a signal applied to CTL also resets the
overcurrent lockout latch.
Enable
EN (enable) is a CMOS compatible input. EN enables or
disables all internal circuitry. The enable threshold is approxi-
mately half the supply voltage. The MIC5031 supply current
is near zero when the driver is disabled (low). See “Applica-
tions Information: Power-Up Sequence.”
Charge Pump
The charge pump produces a voltage that is higher than the
supply voltage. This higher voltage is required to drive the
external N-channel MOSFET in high-side switch circuits.
The charge pump consists of an oscillator and a voltage
tripler. When the driver is enabled, the charge pump is
switched on and off to regulate its output voltage.
External capacitors C1 and C2 are required. The charge
pump will not operate without these capacitors.
Bootstrap Capacitor
The external bootstrap capacitor is necessary to achieve the
fastest gate rise times. The bootstrap capacitor (C3) supplies
additional current at a higher voltage to the gate drive
regulator as the MOSFET is switched on.
When the MOSFET is off, the gate drive regulator voltage is
applied to the boost capacitor . As the MOSFET turns on, the
MOSFET source-to-ground voltage increases. The increas-
ing source voltage is added to the voltage across the capaci-
tor for a voltage doubling effect.
Gate Drive Regulator
The gate drive regulator manages the voltage from the
bootstrap capacitor, the supply, and the charge pump.
The gate drive regulator charges the bootstrap capacitor
when the MOSFET is off and limits the voltage from the
bootstrap capacitor as the MOSFET is switched on. It also
performs skip-mode control by switching the charge pump on
and off to regulate the gate drive output voltage.
Gate Output
When the MIC5031 is enabled and CTL is high, the gate
driver steers regulated voltage to G (gate output). When CTL
is low, the gate driver grounds G. This respectively charges
or discharges the external MOSFET’s gate, .
V
R1
I
R2
RV
R1
External
N-Channel
V
DS
MOSFET
RI
I
R2
1.23V
R2
Voltage Reference (Simplified)
An overcurrent condition also activates the fault flag output
when the lockout latch is activated.
Overcurrent-Shutdown Delay
The overcurrent-shutdown delay circuit permits a delay be-
tween overcurrent detection and latch activation for high-
inrush current loads.
The delay can be increased by adding capacitance from DLY
to GND.
Open-Load Detect
The open load detect resistor is an external high-value pull-
up resistor that causes the source voltage of the external
MOSFET to increase when the load is missing.
The MIC5031 monitors the S-pin voltage only when the gate
driver is off. If the voltage on the S-pin rises above the open-
load detect threshold, the fault flag is activated.
Overtemperature Detect
The overtemperature detect circuit switches the logic to turn
the output off at approximately 140°C. An overtemperature
shutdown condition is restored to normal automatically When
the device cools to about 130°C (10°C hysteresis).
An overtemperature condition also activates the fault flag
output.
Fault Flag
FLT (fault flag) is an open-collector NPN transistor. Fault is
active (pulls collector near ground) upon overcurrent, open-
load, or overtemperature.
August 1999
5
Load
1.23V
Bandgap
Reference
MIC5031
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