0.5A Step-Down Switching Regulator
TC2574
ELECTRICAL CHARACTERISTICS:
Unless otherwise specified, V
IN
= 12V for the 3.3V, 5.0V, and Adjustable
version,V
IN
= 25V for the 12V version. I
LOAD
= 100mA. For typical values T
J
= 25°C, for min/max values T
J
is the operat-
ing junction temperature range that applies (Note 2), unless otherwise noted.
Symbol
I
b
Parameter
Feedback Bias Current
Test Conditions
Min
Typ
Max
Units
nA
TC2574-ADJUSTABLE VERSION [(Note 1) Test Circuit Figure 2]
V
OUT
= 5.0V (Adjustable Version Only)
T
J
= 25°C
T
J
= –40°C to +125°C
Oscillator Frequency (Note 3)
T
J
= 25°C
T
J
= 0 to +125°C
T
J
= –40 to +125°C
Saturation Voltage
I
OUT
= 0.5 A, (Note 4)
T
J
= 25°C
T
J
= –40 to +125°C
Max Duty Cycle (“on”) [Note 5]
Current Limit Peak Current (Notes 3 and 4)
T
J
= 25°C
T
J
= –40 to +125°C
Output Leakage Current (Notes 6 and 7), T
J
= 25°C
Output = 0 V
Output = – 1.0 V
Quiescent Current (Note 6)
T
J
= 25°C
T
J
= –40 to +125°C
Standby Quiescent Current
ON/OFF Pin = 5.0 V (“off”)
T
J
= 25°C
T
J
= –40 to +125°C
ON/OFF Pin Logic Input Level
V
OUT
= 0V
T
J
= 25°C
T
J
= –40 to +125°C
Nominal Output Voltage
T
J
= 25°C
T
J
= –40 to +125°C
ON/OFF Pin Input Current mA
ON/OFF Pin = 5.0V (“off”), T
J
= 25°C
ON/OFF Pin Input Current mA
ON/OFF Pin = 0 (“on”), T
J
= 25°C
—
—
—
47
42
—
—
93
0.7
0.65
—
—
—
—
—
—
25
—
52
52
–
1.0
—
98
1.0
—
0.6
10
5.0
—
60
—
100
200
—
58
63
1.2
1.4
—
1.6
1.8
mA
2.0
30
mA
9.0
11
µA
200
400
V
2.2
2.4
—
—
—
—
1.4
—
1.2
—
15
0
—
—
1.0
0.8
µA
30
µA
5.0
f
O
kHz
V
SAT
V
DC
I
CL
%
A
I
L
I
Q
I
STBY
V
IH
V
IL
I
IH
I
IL
NOTES:
1. External components such as the catch diode, inductor, input and output capacitors can affect the switching regulator system
performance. When the TC2574 is used as shown in the Figure 2 test circuit, the system performance will be as
shown in the system parameters section of the Electrical Characteristics.
2. Tested junction temperature range for the TC2574: T
LOW
= –40°C T high = +125°C
3. The oscillator frequency reduces to approximately 18kHz in the event of an output short or an overload which causes the regulated
output voltage to drop approximately 40% from the nominal output voltage. This self protection feature lowers the average power
dissipation of the IC by lowering the minimum duty cycle from 5% down to approximately 2%.
4. Output (Pin 2) sourcing current. No diode, inductor or capacitor connected to the output pin.
5. Feedback (Pin 4) removed from output and connected to 0 V.
6. Feedback (Pin 4) removed from output and connected to 12V for the Adjustable, 3.3V, and 5.0V versions, and 25V for the 12V
version, to force the output transistor OFF.
7. V
IN
= 40 V.
TC2574-1 1/6/00
3
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