TC2575VAT Просмотр технического описания (PDF) - TelCom Semiconductor Inc => Microchip
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TC2575VAT Datasheet PDF : 25 Pages
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1.0A Step-Down Switching Regulator
TC2575
PIN DESCRIPTION
Pin No.
5-Pin TO-220
1
Symbol
VIN
2
Output
3
GND
4
Feedback
5
ON/OFF
Description
This pin is the positive input supply for the TC2575 step-down
switching regulator. In order to minimize voltage transients and to
supply the switching currents needed by the regulator, a suitable
input bypass capacitor must be present (CIN in Figure 1).
This is the emitter of the internal switch. The saturation voltage
VSAT of this output switch is typically 1.0V. It should be kept in
mind that the PCB area connected to this pin should be kept to a
minimum in order to minimize coupling to sensitive circuitry.
Circuit ground pin. See the information about the printed circuit
boad layout.
This pin senses regulated output voltage to complete the
feedback loop. The signal is divided by the internal resistor
divider network R2, R1 and applied to the non-inverting input of
the internal error amplifier. In the adjustable version of the
TC2575 switching regulator this pin is the direct input of the error
amplifier and the resistor network R2, R1 is connected externally
to allow programming of the output voltage.
It allows the switching regulator circuit to be shut down using
logic level signals, thus dropping the total input supply current to
approximately 80µA. The threshold voltage is typically 1.4V.
Applying a voltage above this value (up to +VIN) shuts the
regulator off. If the voltage applied to this pin is lower than 1.4V
or if this pin is left open, the regulator will be in the "on" condition.
REPRESENTATIVE BLOCK DIAGRAM AND TYPICAL APPLICATION
Unregulated
DC Input
CIN
+VIN
+1
4
Feedback
3.1V Internal
Regulator
ON/OFF
ON/OFF
5
TC2575
Current
R2
Fixed gain
Error Amplifier
Limit +
+
Comparator
–
+
R1
1.0k
–
–
Freq.
Latch
Driver
Shift
18kHz
1.0 Amp
1.235V
Switch
Band-Gap
52kHz
Reference Oscillator
Reset
Thermal
Shutdown
Output
Voltage Versions
R2 (Ω)
3.3V
5.0V
12V
15V
1.7k
3.1k
8.84k
11.3k
For Adjustable version
R1 = open, R2 = 0Ω
Output
L1
Regulated
Output
VOUT
2
GND
+
D1
COUT Load
3
TC2575-1 3/13/00
4
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