ML4812CQX 查看數據表（PDF） - Fairchild Semiconductor
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ML4812CQX Datasheet PDF : 17 Pages
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ML4812
PRODUCT SPECIFICATION
Functional Description
Oscillator
The ML4812 oscillator charges the external capacitor (CT)
with a current (ISET) equal to 5/RSET. When the capacitor
voltage reaches the upper threshold, the comparator changes
state and the capacitor discharges to the lower threshold
through Q1. While the capacitor is discharging, Q2 provides
a high pulse.
The Oscillator period can be described by the following
relationship:
TOSC = TRAMP + TDEADTIME
where:
VOUT
=
------V----I--N--------
1 – DON
and:
TDEADTIME
=
-C----T----×-----V----R----A----M----P---V----A----L---L---E---Y----T---O----P---E---A----K--
8.4mA – ISET
EXTERNAL
CLOCK
CSYNC
RSYNC
SYNC
10
Q2
ISET
RT
9
RT
ISET
CT
16
+
CT
8.4mA
5.6V -
Q1
CLOCK
tD
RAMP PEAK
V(CT)
RAMP VALLEY
Figure 1. Oscillator Block Diagram
6
10
8
10nF
5nF 2nF
5
90%
1nF
3
20nF
2
85%
80%
70%
1
10
100
1000
OSCILLATOR FREQUENCY (kHz)
Figure 2. Oscillator Timing Resistance vs. Frequency
15
VCC
14
VCC = 15V
80µs PULSED LOAD
120Hz RATE
13
SOURCE SATURATION
LOAD TO GROUND
SINK SATURATION
3
LOAD TO VCC
2
1
GND
0
0
200
400
600
800
OUTPUT CURRENT (mA)
Figure 3. Output Saturation Voltage vs. Output Current
REV. 1.0.4 5/31/01
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