TC2574 Datasheet, PDF (3/25 Pages) TelCom Semiconductor, Inc – 0.5A Step-Down Switching Regulator

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
Parameter
Test Conditions
Min
Typ
Max
Units
TC2574-ADJUSTABLE VERSION [(Note 1) Test Circuit Figure 2]
I_b
f_O
V_SAT
DC
Feedback Bias Current
V_OUT = 5.0V (Adjustable Version Only)
nA
T_J = 25°C
—
25
100
T_J = –40°C to +125°C
—
—
200
Oscillator Frequency (Note 3)
T_J = 25°C
T_J = 0 to +125°C
T_J = –40 to +125°C
—
52
—
kHz
47
52
58
42
–
63
Saturation Voltage
I_OUT = 0.5 A, (Note 4)
T_J = 25°C
T_J = –40 to +125°C
V
—
1.0
1.2
—
—
1.4
Max Duty Cycle (“on”) [Note 5]
93
98
—
%
I_CL
Current Limit Peak Current (Notes 3 and 4)
T_J = 25°C
T_J = –40 to +125°C
I_L
Output Leakage Current (Notes 6 and 7), T_J = 25°C
Output = 0 V
Output = – 1.0 V
A
0.7
1.0
1.6
0.65
—
1.8
mA
—
0.6
2.0
—
10
30
I_Q
I_STBY
V_IH
Quiescent Current (Note 6)
Standby Quiescent Current
ON/OFF Pin Logic Input Level
T_J = 25°C
T_J = –40 to +125°C
ON/OFF Pin = 5.0 V (“off”)
T_J = 25°C
T_J = –40 to +125°C
V_OUT = 0V
T_J = 25°C
T_J = –40 to +125°C
mA
—
5.0
9.0
—
—
11
µA
—
60
200
—
—
400
V
2.2
1.4
—
2.4
—
—
V_IL
Nominal Output Voltage
T_J = 25°C
T_J = –40 to +125°C
—
1.2
1.0
—
—
0.8
ON/OFF Pin Input Current mA
µA
I_IH
ON/OFF Pin = 5.0V (“off”), T_J = 25°C
—
15
30
I_IL
ON/OFF Pin Input Current mA
µA
ON/OFF Pin = 0 (“on”), T_J = 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: 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
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