MICREL MIC5018

MIC5018
Micrel
MIC5018
IttyBitty™ High-Side MOSFET Driver
Preliminary Information
General Description
Features
The MIC5018 IttyBitty™ high-side MOSFET driver is designed to switch an N-channel enhancement-type MOSFET
from a TTL compatible control signal in high- or low-side
switch applications. This driver features the tiny 4-lead
SOT-143 package.
The MIC5018 is powered from a +2.7V to +9V supply and
features extremely low off-state supply current. An internal
charge pump drives the gate output higher than the driver
supply voltage and can sustain the gate voltage indefinitely.
An internal zener diode limits the gate-to-source voltage to a
safe level for standard N-channel MOSFETs.
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In high-side configurations, the source voltage of the MOSFET approaches the supply voltage when switched on. To
keep the MOSFET turned on, the MIC5018’s output drives
the MOSFET gate voltage higher than the supply voltage. In
a typical high-side configuration, the driver is powered from
the load supply voltage. Under some conditions, the MIC5018
and MOSFET can switch a load voltage that is slightly higher
than the driver supply voltage.
In a low-side configuration, the driver can control a MOSFET
that switches any voltage up to the rating of the MOSFET.
The gate output voltage is higher than the typical 3.3V or 5V
logic supply and can fully enhance a standard MOSFET.
The MIC5018 is available in the SOT-143 package and
is rated for –40°C to +85°C ambient temperature range.
+2.7V to +9V operation
150µA typical supply current at 5V supply
≤ 1µA typical standby (off) current
Charge pump for high-side low-voltage applications
Internal zener diode gate-to-ground MOSFET protection
Operates in low- and high-side configurations
TTL compatible input
ESD protected
Applications
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Battery conservation
Power bus switching
Solenoid and motion control
Lamp control
Ordering Information
Part Number
Temp. Range
Package
Marking
MIC5018BM4
–40°C to +85°C
SOT-143
H10
5
Typical Applications
+5V
‡
2
4
On
Off
VS
CTL
G
GND
* International Rectifier
100mΩ, 17A max.
TO-220 package
* Siliconix
30mΩ, 7A max., 30V VDS max.
8-lead SOIC package
IRFZ24*
N-Channel
MOSFET
3
1
+2.7 to +9V
4.7µF
MIC5018
2
4
On
Off
Low-Voltage High-Side Power Switch
1997
VLOAD SUPPLY‡
Load
MIC5018
Load
4.7µF
Load voltage limited only by
MOSFET drain-to-source rating
VS
CTL
G
GND
3
1
Si9410DY*
N-channel
MOSFET
Low-Side Power Switch
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MIC5018
Micrel
Pin Configuration
VS
GND
2
1
Part
Identification
Early production identification:
MH10
H10
3
4
G
CTL
SOT-143 (M4)
Pin Description
Pin Number
Pin Name
Pin Function
1
GND
2
VS
Supply (Input): +2.7V to +9V supply.
3
G
Gate (Output): Gate connection to external MOSFET.
4
CTL
Ground: Power return.
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.
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MIC5018
Micrel
Absolute Maximum Ratings
Supply Voltage (VSUPPLY) ........................................... +10V
Control Voltage (VCTL) ................................. –0.6V to +16V
Gate Voltage (VG) ....................................................... +16V
Ambient Temperature Range (TA) ............. –40°C to +85°C
Lead Temperature, Soldering 10sec. ........................ 300°C
Package Thermal Resistance
SOT-143 θJA ..................................................... 220°C/W
SOT-143 θJC ..................................................... 130°C/W
Electrical Characteristics
Parameter
Condition (Note 1)
Supply Current
VSUPPLY = 3.3V
Control Input Voltage
Control Input Current
Min
Typ
Max
Units
VCTL = 0V
VCTL = 3.3V
0.01
70
1
140
µA
µA
VSUPPLY = 5V
VCTL = 0V
VCTL = 5V
0
150
1
300
µA
µA
2.7V ≤ VSUPPLY ≤ 9V
VCTL for logic 0 input
0
0.8
V
2.7V ≤ VSUPPLY ≤ 5V
VCTL for logic 1 input
2.0
VSUPPLY
V
5V ≤ VSUPPLY ≤ 9V
VCTL for logic 1 input
2.4
VSUPPLY
V
1
µA
2.7V ≤ VSUPPLY ≤ 9V
0.01
Control Input Capacitance
Note 2
5
pF
Zener Diode Output Clamp
VSUPPLY = 9V
13
16
19
V
Gate Output Voltage
VSUPPLY = 2.7V
6.3
7.1
V
VSUPPLY = 3.0V
7.1
8.2
V
VSUPPLY = 4.5V
11.4
13.4
V
µA
Gate Output Current
VSUPPLY = 5V
VOUT = 10V, Note 3
9.5
Gate Turn-On Time
VSUPPLY = 4.5V
CL = 1000pF, Note 4
CL = 3000pF, Note 4
0.75
2.1
1.5
4.2
ms
ms
Gate Turn-Off Time
VSUPPLY = 4.5V
CL = 1000pF, Note 5
CL = 3000pF, Note 5
10
30
20
60
µs
µs
General Note: Devices are ESD protected, however handling precautions are recommended.
Note 1:
Typical values at TA = 25°C. Minimum and maximum values indicate performance at –40°C ≥ TA ≥ +85°C. Parts production tested at 25°C.
Note 2:
Guaranteed by design.
Note 3:
Resistive load selected for VOUT = 10V.
Note 4:
Turn-on time is the time required for gate voltage to rise to 4V greater than the supply voltage. This represents a typical MOSFET gate
threshold voltage.
Note 5:
Turn-off time is the time required for the gate voltage to fall to 4V above the supply voltage. This represents a typical MOSFET gate threshold
voltage.
Test Circuit
VSUPPLY
MIC5018
0.1µF
2
4
VS
CTL
G
GND
5V
0V
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1
VOUT
CL
5
MIC5018
Micrel
Typical Characteristics Note 4
20
1.0
8
7
0.8
-40°C
0.6
25°C
0.4
0.2
0
125°C
0
2
4
6
8
SUPPLY VOLTAGE (V)
TURN-OFF TIME (µs)
Note 5
TURN-ON TIME (ms)
SUPPLY CURRENT (mA)
Full Turn-Off Time
vs. Load Capacitance
Full Turn-On Time
vs. Load Capacitance
Supply Current
vs. Supply Voltage
15
VSUPPLY = 3V
10
5V
5
0
0
4
5V
3
2
0
1000 2000 3000 4000 5000
CAPACITANCE (pF)
Gate Output Voltage
vs. Supply Voltage
VSUPPLY = 3V
5
9V
1
9V
10
Note 6
6
0
Gate Output Current
vs. Output Voltage
20
1000 2000 3000 4000 5000
CAPACITANCE (pF)
Gate Output Current
vs. Output Voltage
160
120
-40°C
25°C
10
5
0
2
4
6
8
SUPPLY VOLTAGE (V)
10
120
VSUPPLY = 9V
80
5V
40
0
3V
0
2
4 6 8 10 12 14 16
OUTPUT VOLTAGE (V)
OUTPUT CURRENT (µA)
15
0
Note 4:
OUTPUT CURRENT (µA)
OUTPUT VOLTAGE (V)
125°C
100
80
TA = -55°C
60
25°C
40
125°C
20
0
0
2
4 6 8 10 12 14 16
OUTPUT VOLTAGE (V)
TA = 25°C, VSUPPLY = 5V unless noted.
Note 5:
Full turn-on time is the time between VCTL rising to 2.5V and the VG rising to 90% of its steady on-state value.
Note 6:
Full turn-off time is the time between VCTL falling to 0.5V and the VG falling to 10% of its steady on-state value.
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MIC5018
Micrel
Functional Diagram
+2.7V to +9V
VS
MIC5018
I1
20µA
D2
35V
Q1
CTL
R1 2k
D1
16V
G
EN CHARGE
PUMP
Q2
R2
15k
D3 16V
Q3
GND
Load
On
Off
Functional Diagram with External Components
(High-Side Driver Configuration)
5
Functional Description
Refer to the functional diagram.
The MIC5018 is a noninverting device. Applying a 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.
Supply
(4×). Output voltage is limited to 16V by a zener diode. The
charge pump output voltage will be approximately:
VS (supply) is rated for +2.7V to +9V. An external capacitor
is recommended to decouple noise.
Control
Gate Output
The charge pump output is connected directly to the G (gate)
output. The charge pump is active only when CTL is high.
When CTL is low, Q3 is turned on by the second inverter and
discharges the gate of the external MOSFET to force it off.
CTL (control) is a TTL compatible input. CTL must be forced
high or low by an external signal. A floating input may cause
unpredictable operation.
A high input turns on Q2, which sinks the output of current
source I1, making the input of the first inverter low. The
inverter output becomes high enabling the charge pump.
Charge Pump
The charge pump is enabled when CTL is logic high. The
charge pump consists of an oscillator and voltage quadrupler
1997
VG = 4 × VSUPPLY – 2.8V, but not exceeding 16V.
The oscillator operates from approximately 70kHz to approximately 100kHz depending upon the supply voltage and
temperature.
If CTL is high, and the voltage applied to VS drops to zero, the
gate output will be floating (unpredictable).
ESD Protection
D1 and D2 clamp positive and negative ESD voltages. R1
isolates the gate of Q2 from sudden changes on the CTL
input. Q1 turns on if the emitter (CTL input) is forced below
ground to provide additional input protection. Zener D3 also
clamps ESD voltages for the gate (G) output.
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MIC5018
Micrel
across an IRFZ24 is less than 0.1V with a 1A load and 10V
enhancement. Higher current increases the drain-to-source
voltage drop, increasing the gate-to-source voltage.
Application Information
Supply Bypass
A capacitor from VS to GND is recommended to control
switching and supply transients. Load current and supply
lead length are some of the factors that affect capacitor
size requirements.
+5V
The MIC5018 is designed to drive N-channel enhancementtype MOSFETs. The gate output (G) of the MIC5018 provides a voltage, referenced to ground, that is greater than the
supply voltage. Refer to the “Typical Characteristics: Gate
Output Voltage vs. Supply Voltage” graph.
The supply voltage and the MOSFET drain-to-source
voltage drop determine the gate-to-source voltage.
VGS = VG – (VSUPPLY – VDS)
Logic
High
CTL
GND
3
1
VG
10V
5V
To demonstrate
this circuit, try a
2Ω, 20W
load resistor .
Logic-Level MOSFET
Logic-level N-channel MOSFETs are fully enhanced with a
gate-to-source voltage of approximately 5V and generally
have an absolute maximum gate-to-source voltage of ±10V.
+3.3V
Logic
High
MIC5018
2
4
VS
G
CTL
GND
3
9V
1
Voltages are approximate
IRLZ44* approx. 0V
5.7V
3.3V
* International Rectifier
logic-level MOSFET
To demonstrate
this circuit, try
5Ω, 5W or
47Ω, 1/4W
load resistors.
Figure 3. Using a Logic-Level MOSFET
VDS
S
Refer to figure 3 for an example showing nominal voltages.
The maximum gate-to-source voltage rating of a logic-level
MOSFET can be exceeded if a higher supply voltage is used.
An external zener diode can clamp the gate-to-source voltage as shown in figure 4. The zener voltage, plus its
tolerance, must not exceed the absolute maximum gate
voltage of the MOSFET.
VGS
VLOAD
IRFZ24* approx. 0V
The MIC5018 has an internal zener diode that limits the gateto-ground voltage to approximately 16V.
Lower supply voltages, such as 3.3V, produce lower gate
output voltages which will not fully enhance standard
MOSFETs. This significantly reduces the maximum current
that can be switched. Always refer to the MOSFET data sheet
to predict the MOSFET’s performance in specific applications.
D
G
1
Figure 1. Voltages
The performance of the MOSFET is determined by the gateto-source voltage. Choose the type of MOSFET according to
the calculated gate-to-source voltage.
Standard MOSFET
Standard MOSFETs are fully enhanced with a gate-to-source
voltage of about 10V. Their absolute maximum gate-tosource voltage is ±20V.
With a 5V supply, the MIC5018 produces a gate output of
approximately 15V. Figure 2 shows how the remaining
voltages conform. The actual drain-to-source voltage drop
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VSUPPLY
MIC5018
2
4
VS
CTL
G
GND
Logic-level
N-channel
MOSFET
3
1
5V < VZ < 10V
Protects gate of
logic-level MOSFET
Load
4
G
GND
15V
Figure 2. Using a Standard MOSFET
4.7µF
Load
MIC5018
CTL
3
* International Rectifier
standard MOSFET
VSUPPLY
VS
G
Voltages are approximate
where:
VGS = gate-to-source voltage (enhancement)
VG = gate voltage (from graph)
VSUPPLY = supply voltage
VDS = drain-to-source voltage (approx. 0V at
low current, or when fully enhanced)
2
4
VS
Load
A 4.7µF or 10µF aluminum electrolytic or tantalum capacitor
is suitable for many applications.
The low ESR (equivalent series resistance) of tantalum
capacitors makes them especially effective, but also makes
them susceptible to uncontrolled inrush current from low
impedance voltage sources (such as NiCd batteries or automatic test equipment). Avoid instantaneously applying voltage, capable of high peak current, directly to or near tantalum
capacitors without additional current limiting. Normal power
supply turn-on (slow rise time) or printed circuit trace resistance is usually adequate for normal product usage.
MOSFET Selection
MIC5018
2
Load
4.7µF
Figure 4. Gate-to-Source Protection
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MIC5018
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Split Power Supply
Refer to figure 6. The MIC5018 can be used to control a 12V
load by separating the driver supply from the load supply.
+5V
4.7µF
Inductive loads include relays, and solenoids. Long leads
may also have enough inductance to cause adverse effects
in some circuits.
Logic
High
CTL
G
GND
4
G
CTL
GND
3
15V
1
IRLZ44* approx. 0V
3V
12V
To demonstrate
this circuit, try a
40Ω, 5W or
100Ω, 2W
load resistor.
Figure 6. 12V High-Side Switch
3
A logic-level MOSFET is required. The MOSFET’s maximum
current is limited slightly because the gate is not fully enhanced. To predict the MOSFETs performance for any pair
of supply voltages, calculate the gate-to-source voltage and
refer to the MOSFET data sheet.
1
Schottky
Diode
Figure 5. Switching an Inductive Load
Switching off an inductive load in a high-side application
momentarily forces the MOSFET source negative (as the
inductor opposes changes to current). This voltage spike can
be very large and can exceed a MOSFET’s gate-to-source
and drain-to-source ratings. A Schottky diode across the
inductive load provides a discharge current path to minimize
the voltage spike. The peak current rating of the diode should
be greater than the load current.
In a low-side application, switching off an inductive load will
momentarily force the MOSFET drain higher than the supply
voltage. The same precaution applies.
VGS = VG – (VLOAD SUPPLY – VDS)
VG is determined from the driver supply voltage using the
“Typical Characteristics: Gate Output Voltage vs. Supply
Voltage” graph.
Low-Side Switch Configuration
The low-side configuration makes it possible to switch a
voltage much higher than the MIC5018’s maximum supply
voltage.
+80V
* International Rectifier
standard MOSFET
BVDSS = 100V
Load
4
On
Off
VS
VS
* International Rectifier
logic-level MOSFET
MIC5018
2
MIC5018
2
Voltages are approximate
+2.7V to +9V
4.7µF
+12V
Load
A gate-to-source zener may also be required when the
maximum gate-to-source voltage could be exceeded due to
normal part-to-part variation in gate output voltage. Other
conditions can momentarily increase the gate-to-source voltage, such as turning on a capacitive load or shorting a load.
Inductive Loads
+2.7 to +9V
4.7µF
MIC5018
2
4
On
Off
VS
CTL
G
GND
3
1
To demonstrate
this circuit, try
1k, 10W or
33k, 1/4W
load resistors.
IRF540*
N-channel
MOSFET
Figure 7. Low-Side Switch Configuration
The maximum switched voltage is limited only by the
MOSFET’s maximum drain-to-source ratings.
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