0.5A Step-Down Switching Regulator
TC2574
TYPICAL CHARACTERISTICS (Circuit of Figure 2 Cont.)
Figure 29. Oscillator Frequency
Figure 30. Switch Saturation Voltage
8.0
1.3
1.2
1.1
1.0
0.9
6.0
4.0
V
= 12 V
IN
Normalized at 25°C
2.0
–40
°
C
C
0
0.8
0.7
0.6
0.5
25
°
–2.0
–4.0
–6.0
–8.0
10
125°
C
0.4
0.3
–50
–25
0
25
50
75
100
125
0
0.1
0.2
0.3
0.4
0.5
SWITCH CURRENT (A)
T
JUNCTION TEMPERATURE (°C)
J
Figure 31. Minimum Operating Voltage
Figure 32. Feedback Pin Current
5.0
4.5
4.0
3.5
100
80
Adjustable Version Only
Adjustable Version Only
60
40
20
3.0
2.5
2.0
0
–20
–0
1.5
1.0
0.5
0
V
I
= 1.23V
IN
–60
–80
–100
= 100mA
LOAD
±50
±25
0
25
50
75
100
125
–50
–25
0
25
50
75
100
125
T , JUNCTION TEMPERATURE (
5C)
T
JUNCTION TEMPERATURE (°C)
J
J
Figure 33. Continuous Mode Switching Waveforms
Figure 34. Discontinuous Mode Switching Waveforms
V
= 5.0V, 500mA Load Current, L = 330µH
V
= 5.0V, 100mA Load Current, L = 100µH
OUT
OUT
20V
10V
20V
10V
A
A
B
0
0
0.6A
0.4A
0.2A
0.6A
0.4A
0.2A
B
C
0
0
20mV
AC
20mV
AC
C
5 µsec/DIV
5 µsec/DIV
A: Output Pin Voltage 10V/DIV.
A: Output Pin Voltage 10V/DIV.
B: Inductor Current, 0.2 A/DI.V.
B: Inductor Current, 0.2 A/DI.V.
C: Output Ripple Voltage, 20mV/DIV, AC-Coupled
C: Output Ripple Voltage, 20mV/DIV, AC-Coupled
TC2574-1 1/6/00
22
TELCOM [ TELCOM SEMICONDUCTOR, INC ]
