LTC6101 datasheet(14/20 Pages) LINER

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LTC6101/LTC6101HV

6101fa

Reverse Supply Protection

Some applications may be tested with reverse-polarity

supplies due to an expectation of this type of fault during

operation. The LTC6101 is not protected internally from

external reversal of supply polarity. To prevent damage

that may occur during this condition, a Schottky diode

should be added in series with V– (Figure 7). This will limit

the reverse current through the LTC6101. Note that this

diode will limit the low voltage performance of the LTC6101

by effectively reducing the supply voltage to the part by VD.

In addition, if the output of the LTC6101 is wired to a device

that will effectively short it to high voltage (such as

through an ESD protection clamp) during a reverse supply

condition, the LTC6101’s output should be connected

through a resistor or Schottky diode (Figure 8).

Response Time

The LTC6101 is designed to exhibit fast response to inputs

for the purpose of circuit protection or signal transmis-

sion. This response time will be affected by the external

circuit in two ways, delay and speed.

If the output current is very low and an input transient

occurs, there may be an increased delay before the output

voltage begins changing. This can be improved by in-

creasing the minimum output current, either by increasing

RSENSE or decreasing RIN. The effect of increased output

current is illustrated in the step response curves in the

Typical Performance Characteristics section of this

datasheet. Note that the curves are labeled with respect to

the initial output currents.

The speed is also affected by the external circuit. In this

case, if the input changes very quickly, the internal ampli-

fier will slew the gate of the internal output FET (Figure 1)

in order to maintain the internal loop. This results in

current flowing through RIN and the internal FET. This

current slew rate will be determined by the amplifier and

FET characteristics as well as the input resistor, RIN. Using

a smaller RIN will allow the output current to increase more

quickly, decreasing the response time at the output. This

will also have the effect of increasing the maximum output

current. Using a larger ROUT will decrease the response

time, since VOUT = IOUT • ROUT. Reducing RIN and increas-

ing ROUT will both have the effect of increasing the voltage

gain of the circuit.

Figure 7. Schottky Prevents Damage During Supply Reversal

Figure 8. Additional Resistor R3 Protects

Output During Supply Reversal

6101 F07

LTC6101

4.99k

100

VBATT

RSENSE

–

6101 F08

ADC

LTC6101

4.99k

100

VBATT

RSENSE

–

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