TPS2061DBVRG4 datasheet(19/55 Pages) TI2

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8.5 Enable ( ENx or ENx)

The logic enable disables the power switch and the bias for the charge pump, driver, and other circuitry to

reduce the supply current. The supply current is reduced to less than 1 μA when a logic high is present on ENx,

or when a logic low is present on ENx. A logic zero input on ENx, or a logic high input on ENx restores bias to

the drive and control circuits and turns the switch on. The enable input is compatible with both TTL and CMOS

logic levels.

8.6 Current Sense

A sense FET monitors the current supplied to the load. The sense FET measures current more efficiently than

conventional resistance methods. When an overload or short circuit is encountered, the current-sense circuitry

sends a control signal to the driver. The driver in turn reduces the gate voltage and drives the power FET into its

saturation region, which switches the output into a constant-current mode and holds the current constant while

varying the voltage on the load.

8.7 Overcurrent

A sense FET is employed to check for overcurrent conditions. Unlike current-sense resistors, sense FETs do

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

maintains a constant output current and reduces the output voltage accordingly. Complete shutdown occurs only

if the fault is present long enough to activate thermal limiting.

There are two kinds of current limit profiles for the TPS20xx family of devices.

The TPS2063 and TPS2067 have an output I vs V characteristic similar to the plot labeled Current Limit

with Peaking in Figure 8-4. This type of limiting can be characterized by two parameters, the overcurrent trip

threshold (IOC), and the short-circuit output current threshold (IOS).

The TPS2061, TPS2062, TPS2065, and TPS2066 have an output I vs V characteristic similar to the plot labeled

Flat Current Limit in Figure 8-4. This type of limiting can be characterized by one parameters, the short circuit

current (IOS).

IOUT

IOS

Decreasing

Load

Resistance

VIN

0 A

0 V

Slope = -RDS(ON)

IOUT

IOS

Decreasing

Load

Resistance

VIN

0 A

0 V

Slope = -RDS(ON)

IOC

Current Limit

with Peaking

Flat Current

Limit

Figure 8-4. Current Limit Profiles

8.7.1 Overcurrent Conditions (TPS2063 and TPS2067)

Three possible overload conditions can occur for the TPS2063 and TPS2067. In the first condition, the output

has been shorted before the device is enabled or before VI(IN) has been applied (see Figure 6-34 through Figure

6-36). The TPS2063 and TPS2067 senses the short and immediately switches into a constant-current output.

In the second condition, a short or an overload occurs while the device is enabled. At the instant the overload

occurs, high currents may flow for a short period of time before the current-limit circuit can react. After the

current-limit circuit has tripped (reached the overcurrent trip threshold (IOC)), the device switches into constant-

current mode and current is limited at the short-circuit output current threshold (IOS).

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

current is permitted to rise until the overcurrent trip threshold (IOC) is reached or until the thermal limit of

the device is exceeded. The TPS2063 and TPS2067 are capable of delivering current up to the current-limit

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TPS2061, TPS2062, TPS2063

TPS2065, TPS2066, TPS2067

SLVS490K – DECEMBER 2003 – REVISED JUNE 2024

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