TPS2014, TPS2015

POWER DISTRIBUTION SWITCHES

SLVS159B – DECEMBER 1996 – REVISED AUGUST 1997

16

POST OFFICE BOX 655303

APPLICATION INFORMATION

Figure 24. Typical Application

OUT

OUT

OUT

2

3

5

4

EN

OC

IN

IN

7

8

6

22

µF

0.1

µF

10 k

Ω

Power Supply

4 V – 5 V

Overcurrent Output

Load Enable

TPS2014

External Load

1

GND

0.1

µF

+

power supply considerations

The TPS20xx has multiple inputs and outputs that must be connected in parallel to minimize voltage drop and

prevent unnecessary power dissipation.

A 0.1-

µF ceramic bypass capacitor between IN and GND, close to the device, is recommended. A high-value

electrolytic capacitor is also desirable when the output load is heavy or has large paralleled capacitors.

Bypassing the output with a 0.1-

µF ceramic capacitor improves the immunity of the device to electrostatic

discharge (ESD).

overcurrent

A sense FET is employed to check for overcurrent conditions. Unlike sense resistors and polyfuses, sense FETs

do not increase series resistance to the current path. When an overcurrent condition is detected, the device

maintains a constant output current and reduces the output voltage accordingly. Shutdown only occurs when

the fault is present long enough to activate thermal limiting.

Three possible overload conditions can occur. In the first condition, the output has been shorted before the

immediately switches into a constant-current output.

Under the second condition, the short occurs while the device is enabled. At the instant the short occurs, very

high currents flow for a short time before the current-limit circuit can react (see Figures 3 and 4). After the

current-limit circuit has tripped, the device limits normally.

Under the third condition, the load has been gradually increased beyond the recommended operating current.

The current is permitted to rise until the current-limit threshold is reached (see Figures 5 and 6). The TPS20xx

is capable of delivering current up to the current-limit threshold without damage. When the threshold has been

reached, the device switches into its constant-current mode.