Datasheet

I (mA)=C ( F) 0.07(V/ s)+I (mA)m m
LOAD
SOFTSTART OUT
´
Thermal
Shutdown
Current
Limit
UVLO
Bandgap
IN
EN
OUT
EEPROM
LOGIC
TPS72710 , TPS72711 , TPS72715 , TPS727185 , TPS72718 , TPS72719 , TPS72725
TPS72727 , TPS727285 , TPS72728 , TPS72730 , TPS72733 , TPS72748 , TPS72750
SBVS128D –JUNE 2009–REVISED FEBRUARY 2014 www.ti.com
7 Detailed Description
7.1 Overview
The TPS727xx family belongs to a family of new generation LDO regulators that consume extremely low
quiescent current while simulatenously delivering excellent PSRR with very little headroom (V
IN
– V
OUT
differential
voltage), and very good transient response. These features, combined with low noise without a noise reduction
terminal in an ultrasmall package, make this device ideal for portable applications. This family of regulators offers
sub-bandgap output voltages, current limit and thermal protection, and is fully specified from –40°C to +125°C.
7.2 Functional Block Diagram
Figure 25. Functional Block Diagram
7.3 Feature Description
7.3.1 Internal Current Limit
The TPS727xx internal current limit helps protect the regulator during fault conditions. During current limit, the
output sources a fixed amount of current that is largely independent of output voltage. In such a case, the output
voltage is not regulated, and is V
OUT
= I
LIMIT
× R
LOAD
. The PMOS pass transistor dissipates (V
IN
– V
OUT
) × I
LIMIT
until thermal shutdown is triggered and the device is turned off. As the device cools down, it is turned on by the
internal thermal shutdown circuit. If the fault condition continues, the device cycles between current limit and
thermal shutdown. See the Thermal Protection section for more details.
The PMOS pass element in the TPS727xx has a built-in body diode that conducts current when the voltage at
the OUT terminal exceeds the voltage at the IN terminal. This current is not limited, so if extended reverse
voltage operation is anticipated, external limiting to 5% of rated output current is recommended.
7.3.2 Soft Start
The startup current is given by Equation 1:
(1)
This equation shows that soft-start current is directly proportional to C
OUT
.
The output voltage ramp rate is independent of C
OUT
and load current, and has a typical value of 0.07 V/μs.
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Product Folder Links: TPS72710 TPS72711 TPS72715 TPS727185 TPS72718 TPS72719 TPS72725 TPS72727
TPS727285 TPS72728 TPS72730 TPS72733 TPS72748 TPS72750