Datasheet

www.ti.com
R1 

V
O
V
ref
 1

 R2
(4)
V
O
V
I
OUT
FB
R2
GND
EN
IN
≤0.9 V
≥1.7 V
TPS72101
OUTPUT
VOLTAGE
(V)
R1 R2
2.5 127 121
OUTPUT VOLTAGE
PROGRAMMING GUIDE
DIVIDER RESISTANCE
(kΩ)
1
Note (1): 1% values shown.
3
1
4
2
R1
5
0.1 µF
0.1 µF
REGULATOR PROTECTION
TPS72101 , , TPS72115
TPS72116 , TPS72118
SLVS352C – DECEMBER 2001 – REVISED MARCH 2006
APPLICATION INFORMATION (continued)
Resistors R1 and R2 should be chosen for approximately 10-µA divider current. Lower value resistors can be
used but offer no inherent advantage and waste more power. Higher values should be avoided, as leakage
currents at FB increase the output voltage error. The recommended design procedure is to choose R2 = 30.1 k Ω
to set the divider current at 10 µA and then calculate R1 using Equation 4 :
Where:
• V
ref
= 1.225 V.
Figure 20. TPS72101 Adjustable LDO Regulator Programming
The TPS721xx pass element has a built-in back diode that safely conducts reverse current when the input
voltage drops below the output voltage (for example, during power down). Current is conducted from the output
to the input and is not internally limited. If extended reverse voltage is anticipated, external limiting might be
appropriate.
The TPS721xx also features internal current limiting and thermal protection. During normal operation, the
TPS721xx limits output current to approximately 350 mA. When current limiting engages, the output voltage
scales back linearly until the overcurrent condition ends. While current limiting is designed to prevent gross
device failure, care should be taken not to exceed the power dissipation ratings of the package. If the
temperature of the device exceeds 170°C, thermal-protection circuitry shuts it down. Once the device has cooled
down to below 150°C, regulator operation resumes.
9
Submit Documentation Feedback