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Teilenummer | GL494 |
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Beschreibung | PWM CONTROL CIRCUIT | |
Hersteller | Hynix Semiconductor | |
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Gesamt 7 Seiten GL494
GL494
PWM CONTROL CIRCUIT
Description
The GL494 incorporates on a single monolithic chip all the
functions required in the construction of a pulse-width-
modulation control circuit. Designed primarily for power
supply control, the GL494 contains an on-chip 5-volt
regulator, two error amplifiers, adjustable oscillator, dead-
time control comparator, pulse-steering flip-flop, and
output-control circuitry. The uncommitted output
transistors pro-vide either common-emitter or emitter-
follower output capability. Push-pull or single-ended
output operation may be selected through the output-
control function. The ar-chitecture of the GL494 prohibits
the possibility of either output being pulsed twice during
push-pull operation.
Features
— Complete PWM Power Control Circuitry
— Uncommitted Outputs for 200mA Sink or Source
— Output Control Selects Single-Ended or Push-Pull
Operation
— Internal Circuitry Prohibits Double Pulse at Either
Output
— Internal Regulator Provides a Stable 5V Reference
Supply
— Variable Dead-Time Provides Control Over Total
Range
Pin Configuration
NONINV INPUT
INV. INPUT
FEEDBACK
DEAD TIME CONTROL
Cr
Rr
GND
C1
1
2
3
4
5
6
7
8
16 NON INV INPUT
15 INV. INPUT
14 REF. OUT
13 OUTPUT CONTROL
12 Vcc
11 C2
10 E2
9 E1
Function Table
Output Control
Grounded
At Vref
Output Function
Single-ended or Parallel Output
Normal Push-Pull Operation
Block Diagram
RT
CT OSCILLATOR
DEAD 0.1V
TIME
CONTROL (4)
ERROR AMPLIFIERS
NONINVERTING(1)
INPUT
+
INVERTING (2)
−
INPUT
ERROR AMP1
NONINVERTING(16)
INPUT
INVERTING (15)
INPUT
(3)
FEEDBACK
+
−
ERROR AMP2
OUTPUT
CONTROL
(See Function Table)
PULSE STEERING
(13)
FLIP FLOP
Q
T
PWM
COMPARATOR
Q
REFERENCE
REGULATOR
VCC
(12)
REF OUT
(14)
GND
(7)
E1(9) C1(8)
E1(10) C2(11)
1
4. Emitter-Follower Configuration
GL494
(EACH OUTPUT
EIRCUIT)
15V
90%
90%
CL=15pF
(INCLUDES PROBE AND
JIG CAPACITANCE)
TEST CIRCUIT
Typical Performance Curves
OUTPUT
68Ω
2W
10%
tr
10%
tf
OUTPUT VOLTAGE WAVEFORM
FIGURE 1 – OSCILLATOR FREQUENCY versus
300k TIMING RESISTANCE
100k
0.001 µF
Vcc=15V
10k
CT=0.01 µF
1k
100
30
1k 2k
0.1 µF
0.1 µF
5k 10k 20k 50k 100k 200k 500k 1M
RT, TIMING RESISTANCE (Ω)
FIGURE 2 – OPEN LOOP VOLTAGE GAIN AND PHASE
100
versus FREQUENCY
20
90 0
80
Vcc=15V
Vo=3V
-20
70
AVOL
RL=2kΩ
-40
60 -60
50 θ -80
40 -100
30 -120
20 -140
10 -160
0 -80
1.0 10 100 1k 10k 100k 1M
f, FREQUENCY (Hz)
FIGURE 3 – PERCENT DEAD TIME
versus OSCILLATOR FREQUENCY
10
9
8 Vcc=15V
Voc=Vref
7 V(PIN4)=0V
6
5
4
3
2
1
0
100
1k
CT=0.01 µF
0.01 µF
10k
fo, OSCILLATOR FREQUENCY (Hz)
100k
FIGURE 4 – PERCENT DUTY CYCLE versus
DEAD-TIME CONTROL VOLTAGE
50
Vcc=15V
40 Voc=Vref
1) CT=0.01
30
1 RT=10k
2) CT=0.001
RT=30K
20 2
10
0
0
1.0 2.0
3.0 3.5
DEAD TIME CONTROL VOLTAGE (V)
6
6 Page | ||
Seiten | Gesamt 7 Seiten | |
PDF Download | [ GL494 Schematic.PDF ] |
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