MIC1555 Ver la hoja de datos (PDF) - Micrel
Número de pieza
componentes Descripción
Fabricante
MIC1555 Datasheet PDF : 10 Pages
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Micrel, Inc.
MOSFET may be driven by a second MIC1555/7,
powered by 12V to 15V, to level-shift the input.
+5V +12V
OFF 3.3V
ON 1.6V
MIC1555
5 THR
VS 1
RL
4 TRG
2 GND OUT 3
Figure 7. Schmitter Trigger
Charge-Pump Low-Side MOSFET Drivers
A standard MOSFET requires approximately 15V to fully
enhance the gate for minimum RDS(on). Substituting a
logic-level MOSFET reduces the required gate voltage,
allowing an MIC1557 to be used as an inverting Schmitt
Trigger, described above. An MIC1557 may be
configured as a voltage quadrupler to boost a 5V input to
over 15V to fully enhance an N-channel MOSFET which
may have its drain connected to a higher voltage,
through a high-side load. ATTL high signal applied to CS
enables a 10kHz oscillator, which quickly develops 15V
at the gate of the MOSFET, clamped by a zener diode. A
resistor from the gate to ground ensures that the FET
will turn off quickly when the MIC1557 is turned off.
MIC1555/1557
TTL High = ON
+12V
N-Channel
MOSFET RL
(IRF540)
C1
100pF
to 10µF
+5V
15V
MIC1557
43
VS
CS
1
T/T
2
GND
5
OUT
RT 1k to 1M
RE
100k
Figure 8. Charge-Pump
Audible Voltmeter
If an additional charge or discharge source is connected
to the timing capacitor, the frequency may be shifted by
turning the source on or off. An MIC1555 oscillator,
powered by the circuit under test, may be used to drive a
small loud speaker or piezo-electric transducer to
provide a medium frequency for an open or high
impedance state at the probe. A high tone is generated
for a high level, and a lower frequency for a logic low on
the probe.
RT 10k
+5V to +18V
1N914
47k
10k
CT
0.01µF
MIC1555
5 THR
1
VS
4 TRG
2 GND
3
OUT
0.001µF
10k
100
Figure 9. Audible Voltmeter
May 2010
9
M9999-052610-D
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