Datasheet LT1528 (Analog Devices) - 10

LT1528
APPLICATIONS INFORMATION
The reverse output current will follow the curve in Figure When the input of the LT1528 is forced to a voltage below 3 when the input is pulled to ground. This current fl ows its nominal output voltage and its output is held high, the through the OUTPUT pin to ground. The state of the output current will follow the curve shown in Figure 3. SHDN pin will have no effect on output current when the This can happen if the input of the LT1528 is connected input pin is pulled to ground. to a low voltage and the output is held up by a second regulator circuit. When the input pin is forced below the In some applications it may be necessary to leave the 0utput pin or the OUTPUT pin is pulled above the input input on the LT1528 unconnected when the output is held pin, the input current will typically drop to less than 2μA high. This can happen when the LT1528 is powered from (see Figure 4). The state of the SHDN pin will have no a rectifi ed AC source. If the AC source is removed, then effect on the reverse output current when the output is the input of the LT1528 is effectively left fl oating. The pulled above the input. reverse output current also follows the curve in Figure 3 if the input pin is left open. The state of the SHDN pin will have no effect on the reverse output current when the input pin is fl oating. 1000 5 TJ = 25°C, VIN = 0V VOUT = 3.3V 900 VOUT = VSENSE CURRENT FLOWS 800 4 INTO DEVICE 700 600 3 500 400 2 300 OUTPUT CURRENT (μA) INPUT CURRENT (μA) 200 1 100 0 0 0 1 2 3 4 5 6 7 8 9 10 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 OUTPUT VOLTAGE (V) INPUT VOLTAGE (V) 1528 F03 1528 F04
Figure 3. Reverse Output Current Figure 4. Input Current
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