ADP1196ACBZ-R7 datasheet(11/12 Pages) AD

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Data Sheet

ADP1196

Rev. 0 | Page 11 of 12

TIMING

Turn-on delay is defined as the interval between the time that

VVB_EN exceeds the rising threshold voltage and when VOUT rises

to ~10% of its final value. The ADP1196 includes circuitry that has

a typical 2 ms turn-on delay and a controlled rise time to limit

the VIN inrush current. As shown in Figure 25 and Figure 26,

the turn-on delay is nearly independent of the input voltage.

Figure 25. Typical Turn-On Time and Inrush Current,

VIN = 1.8 V, COUT = 47 μF, 330 Ω Load

Figure 26. Typical Turn-On Time and Inrush Current,

VIN = 5 V, COUT = 47 μF, 330 Ω Load

The rise time is defined as the time it takes the output voltage

(VOUT) to rise from 10% to 90% of its final value. The output

voltage rise time is dependent on the rise time of the internal

charge pump.

For very large values of output capacitance, the RC time constant

(where C is the load capacitance (CLOAD) and R is the RDSON||RLOAD)

can become a factor in the rise time of the output voltage. Because

RDSON is much smaller than RLOAD, an adequate approximation

for RC is RDSON × CLOAD. An input or load capacitor is not required

for the ADP1196, although capacitors can be used to suppress

noise on the board.

The turn-off time is defined as the time it takes for the output

voltage to fall from 90% to 10% of VOUT. It is also dependent on

the RC time constant of the output capacitance and load resistance.

Figure 27 shows the typical turn-off times with VIN = 1.8 V, VIN =

3.3 V, and VIN = 5.0 V, COUT = 47 μF, and RLOAD = 330 Ω.

Figure 27. Typical Turn-Off Time, VIN = 1.8 , VIN = 3.3 V, and VIN = 5.0 V,

COUT = 47 μF, RLOAD = 330 Ω

CURRENT-LIMIT AND THERMAL OVERLOAD

PROTECTION

The ADP1196 is protected against damage due to excessive power

dissipation by current and thermal overload protection circuits.

The ADP1196 is designed to limit current when the output load

reaches 4 A. When the output load exceeds 4 A, the output voltage

is reduced to maintain a constant current limit.

Thermal overload protection is included, which limits the junction

temperature to a maximum of 125°C (typical). Under extreme

conditions (that is, high ambient temperature and/or high power

dissipation), when the junction temperature starts to rise above

125°C, the output is turned off, reducing the output current to

zero. When the junction temperature falls below 110°C, the

output is turned on again, and output current is restored to its

operating value.

Consider the case where a hard short from VOUT to GND occurs.

At first, the ADP1196 limits current, so that only 4 A conducts into

the short. If the self-heating of the junction is great enough to

cause its temperature to rise above 125°C, thermal shutdown is

activated, turning off the output and reducing the output current to

zero. As the junction temperature cools and falls below 110°C, the

output turns on and conducts 4 A into the short, again causing the

junction temperature to rise above 125°C. This thermal oscillation

between 110°C and 125°C causes a current oscillation between 4 A

and 0 mA that continues as long as the short remains at the output.

Current and thermal limit protections are intended to protect

the device against accidental overload conditions. For reliable

operation, device power dissipation must be externally limited

so that junction temperature does not exceed 125°C.

CH1 20mAΩ

CH2 1V

M1ms

A CH2

1.18V

T 10.6%

CH3 500mV BW

VOUT

INPUT CURRENT

ENABLE

CH1 20mAΩ

CH2 1V

M1ms

A CH2

1.18V

T 10.6%

CH3 2V BW

VOUT

INPUT CURRENT

ENABLE

1.0

2.0

3.0

4.0

5.0

6.0

0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10

TIME (SEC)

VVB_EN

VIN = 5.0V

VIN = 3.3V

VIN = 1.8V

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