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參數(shù)資料
| 型號(hào)： | MIC5020BN |
| 廠商： | MICREL INC |
| 元件分類： | 功率晶體管 |
| 英文描述： | Replaced by PTN78060W : |
| 中文描述： | BUF OR INV BASED MOSFET DRIVER, PDIP8 |
| 封裝： | PLASTIC, DIP-8 |
| 文件頁(yè)數(shù)： | 6/7頁(yè) |
| 文件大?。?/td> | 99K |
| 代理商： | MIC5020BN |
MIC5020
Micrel
October 1998
5-167
5
Lamp Driver Application
Incandescent lamps have a high inrush current (low resis-
tance) when turned on. The MIC5020 can perform a “soft
start” by pulsing the MOSFET (overcurrent condition) until
the filament is warm enough for its current to decrease
(resistance increases). The sense resistor is selected so the
voltage across the sense resistor drops below the sense
threshold (50mV) as the filament becomes warm. The
MOSFET is no longer pulsed to limit current and the lamp
turns completely on.
V
DD
Input
Fault
C
T
Gate
Sense
Sense
+
Gnd
TTL Input
(0V/5V)
R
(0.041
)
N-Channel
Power MOSFET
(IRF540)
V+
MIC5020
1
2
3
4
8
7
6
5
10μF
Incandescent
Lamp (#1157)
(+11V to +12V)
“( )” values apply to
demo circuit. See text.
Figure 1. Lamp Driver with
Current Sensing
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.
Soft start can be demonstrated using a #1157 dual-filament
automotive lamp. The value of R
S
shown in figure 1 allows for
soft start of the higher-resistance filament (measures approx.
2.1
cold or 21
hot).
Solenoid Driver Application
The MIC5020 can be directly powered by the control voltage
supply in typical 11Vdc through 50Vdc control applications.
Current sensing has been omitted as an example.
V
DD
Input
Fault
C
T
Gate
Sense
Sense
+
Gnd
TTL Input
N-Channel
Power MOSFET
V+
MIC5020
1
2
3
4
8
7
6
5
10μF
Diode
Solenoid
+11V to +50V
Figure 2. Solenoid Driver,
Without Current Sensing
A diode across the load protects the MOSFET from the
voltage spike generated by the inductive load upon MOSFET
turn off. The peak forward current rating of the diode should
be greater than the load current.
Current Sensing MOSFET Application
A current sensing MOSFET allows current sensing without
adding additional resistance to the power switching circuit.
A current sensing MOSFET has two source connections: a
“power source” for power switching and a “current source” for
current sensing. The current from the current source is
approximately proportional to the current through the power
source, but much smaller. A current sensing ratio (I
SOURCE
/
I
SENSE
) is provided by the MOSFET manufacturer.
V
DD
Input
Fault
C
T
Gate
Sense
Sense
+
Gnd
TTL Input
(0V/5V)
N-Channel
Current Sensing
Power MOSFET
(IRCZ24)
V+
MIC5020
1
2
3
4
8
7
6
5
10μF
L
R
SENSE
(10
)
+11V to +50V
(+13.2V)
(+13.2V, > 4.4A)
(3
, > 60W)
“( )” values apply to
demo circuit. See text.
Figure 3. Using a Current Sensing MOSFET
The MOSFET current source is used to develop a voltage
across a sense resistor. This voltage is monitored by the
MIC5020 (
SENSE
+ and
SENSE
– pins) to identify an overcur-
rent condition.
The value of the sense resistor can be estimated with:
R
SENSE
= (r V
TRIP
R
DS(ON)
) / (I
LOAD
R
DS(ON)
– V
TRIP
)
where:
R
SENSE
= external “sense” resistor
V
TRIP
= 50mV (0.050V) for the MIC5020
r = manufacturer’s current sense ratio: (I
SOURCE
/I
SENSE
)
R
DS(ON)
= manufacturer’s power source on resistance
I
LOAD
= load current (power source current)
The drain to source voltage under different fault conditions
affects the behavior of the MOSFET current source; that is,
the current source will respond differently to a slight over-
current condition (V
DS(ON)
very small) than to a short circuit
(where V
DS(ON)
is approximately equal to the supply voltage).
Adjustment of the sense resistor value by experiment starting
from the above formula will provide the quickest selection of
R
SENSE
.
Refer to manufacture’s data sheets and application notes for
detailed information on current sensing MOSFET character-
istics.
Figure 3 includes values which can be used to demonstrate
circuit operation. The IRCZ24 MOSFET has a typical sense
ratio of 780 and a R
DS(ON)
of 0.10
. A large 3
wirewound
load resistor will cause inductive spikes which should be
suppressed using a diode (using the same configuration as
figure 2).
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MIC5021 | Replaced by PTN78060W : |
| MIC5021BM | Replaced by PTN78060W : |
| MIC5021BN | Replaced by PTN78060W : |
| MIC5031 | High-Speed High-Side MOSFET Driver(高速高邊MOS場(chǎng)效應(yīng)管驅(qū)動(dòng)器) |
| MIC5031BM | High-Speed High-Side MOSFET Driver |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MIC5020YM | 功能描述:功率驅(qū)動(dòng)器IC High Speed Low Side MOSFET Driver - Lead Free RoHS:否 制造商:Micrel 產(chǎn)品:MOSFET Gate Drivers 類型:Low Cost High or Low Side MOSFET Driver 上升時(shí)間: 下降時(shí)間: 電源電壓-最大:30 V 電源電壓-最小:2.75 V 電源電流: 最大功率耗散: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| MIC5020YM TR | 功能描述:功率驅(qū)動(dòng)器IC High Speed Low Side MOSFET Driver - Lead Free RoHS:否 制造商:Micrel 產(chǎn)品:MOSFET Gate Drivers 類型:Low Cost High or Low Side MOSFET Driver 上升時(shí)間: 下降時(shí)間: 電源電壓-最大:30 V 電源電壓-最小:2.75 V 電源電流: 最大功率耗散: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Tube |
| MIC5020YM | 制造商:Micrel Inc 功能描述:ICSingle MOSFET DriverSOP8PINPLASTIC |
| MIC5021 | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:High-Speed High-Side MOSFET Driver |
| MIC5021_05 | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:High-Speed High-Side MOSFET Driver |
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