0.5A Step-Down Switching Regulator
TC2574
ELECTRICAL CHARACTERISTICS: Unless otherwise specified, VIN = 12V for the 3.3V, 5.0V, and Adjustable
version,VIN = 25V for the 12V version. ILOAD = 100mA. For typical values TJ = 25°C, for min/max values TJ is the operat-
ing junction temperature range that applies (Note 2), unless otherwise noted.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Units
TC2574-ADJUSTABLE VERSION [(Note 1) Test Circuit Figure 2]
Ib
Feedback Bias Current
VOUT = 5.0V (Adjustable Version Only)
TJ = 25°C
nA
—
—
25
—
100
200
TJ = –40°C to +125°C
fO
Oscillator Frequency (Note 3)
Saturation Voltage
TJ = 25°C
TJ = 0 to +125°C
TJ = –40 to +125°C
—
47
42
52
52
–
—
58
63
kHz
V
VSAT
IOUT = 0.5 A, (Note 4)
TJ = 25°C
TJ = –40 to +125°C
—
—
1.0
—
1.2
1.4
DC
ICL
Max Duty Cycle (“on”) [Note 5]
93
98
—
%
A
Current Limit Peak Current (Notes 3 and 4)
TJ = 25°C
TJ = –40 to +125°C
Output Leakage Current (Notes 6 and 7), TJ = 25°C
0.7
0.65
1.0
—
1.6
1.8
IL
mA
mA
µA
V
Output = 0 V
Output = – 1.0 V
—
—
0.6
10
2.0
30
IQ
Quiescent Current (Note 6)
Standby Quiescent Current
ON/OFF Pin Logic Input Level
TJ = 25°C
TJ = –40 to +125°C
—
—
5.0
—
9.0
11
ISTBY
ON/OFF Pin = 5.0 V (“off”)
TJ = 25°C
TJ = –40 to +125°C
—
—
60
—
200
400
VIH
VIL
VOUT = 0V
TJ = 25°C
TJ = –40 to +125°C
2.2
2.4
1.4
—
—
—
Nominal Output Voltage
TJ = 25°C
TJ = –40 to +125°C
—
—
1.2
—
1.0
0.8
ON/OFF Pin Input Current mA
ON/OFF Pin Input Current mA
µA
µA
IIH
IIL
ON/OFF Pin = 5.0V (“off”), TJ = 25°C
—
15
30
ON/OFF Pin = 0 (“on”), TJ = 25°C
—
0
5.0
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: TLOW = –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. VIN = 40 V.
3
TC2574-1 1/6/00
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