SG3525A SG3527A
Figure 1. Oscillator Charge Time versus RT
200
100
RT, TIMING RESISTOR (k
Ω
)
50
20
10
6
5
RT
* RD = 0
Ω
Figure 2. Oscillator Discharge Time versus RD
500
R D , DEAD TIME RESISTOR (
Ω
)
400
300
200
100
0
5.0
2.0
2.0
5.0 10
20
50
RD *
CT
7
100 200 500 1000 2000 5000 10,000
CHARGE TIME (µs)
0.2
0.5
1.0
2.0
5.0
10
20
50
100 200
DISCHARGE TIME (µs)
Figure 3. Error Amplifier Open Loop
Frequency Response
1
2
–
+
9
Figure 4. Output Saturation
Characteristics (SG3525A)
V sat , SATURATION VOLTAGE (V)
A VOL, VOLTAGE GAIN (dB)
100
80
60
40
20
0
–20
1.0
10
100
1.0 k
10 k
100 k
1.0 M
RZ = 20 k
CP
RZ
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
0.01
VCC = +20 V
TJ = +25°C
Source Sat, (VC–VOH)
Sink Sat, (VOL)
0.02 0.03 0.05 0.07 0.1
0.2 0.3
0.5 0.7 1.0
IO, OUTPUT SOURCE OR SINK CURRENT (A)
10 M
f, FREQUENCY (Hz)
Figure 5. Oscillator Schematic (SG3525A)
Vref
16
Q1
RT
CT
Q5
Q8
7.4k
6
5
Q3
Q6
Q9
2.0k
Q10
Ramp
To PWM
25k
Blanking
Q14 To Output
Figure 6. Error Amplifier Schematic (SG3525A)
15
VCC
Q3
14k
Q11
3
Sync
7
Discharge
Q2
12
Gnd
2.0k
5.0pF
Q4
Q7
1.0k
400µA
23k
Inverting
Q1
Input
1
Noninverting
Input
2
200µA
Q4
Q2
To PWM
Comparator
100µA
5.8V 30
9
Compensation
1.0k
Q12
Q13
3.0k
250
4
OSC Output
MOTOROLA ANALOG IC DEVICE DATA
5
MOTOROLA [ MOTOROLA, INC ]
