Datasheet
SGLS247A − JUNE 2004 − REVISED JUNE 2008
www.ti.com
14
APPLICATION INFORMATION
V
O
V
I
OUT
FB
R2
GND
EN
IN
≤0.5 V
≥2 V
TPS76301
1 µF
OUTPUT
VOLTAGE
(V)
R1 R2
2.5
3.3
3.6
4
5
6.45
187
301
348
402
549
750
169
169
169
169
169
169
OUTPUT VOLTAGE
PROGRAMMING GUIDE
DIVIDER RESISTANCE
(kΩ)
(1)
(1)
1% values shown.
3
1
4
2
R1
5
CSR = 1 Ω
4.7 µF
+
Figure 21. TPS76301 Adjustable LDO Regulator Programming
power dissipation and junction temperature
Specified regulator operation is assured to a junction temperature of 125°C; the maximum junction temperature allowable
to avoid damaging the device is 150°C. This restriction limits the power dissipation the regulator can handle in any given
application. To ensure the junction temperature is within acceptable limits, calculate the maximum allowable dissipation,
P
D(max)
and the actual dissipation, P
D
, which must be less than or equal to P
D(max)
.
The maximum-power-dissipation limit is determined using the following equation:
P
D(max)
+
T
J
max * T
A
R
qJA
Where:
T
J
max is the maximum allowable junction temperature
R
θJA
is the thermal resistance junction-to-ambient for the package, see the dissipation rating table.
T
A
is the ambient temperature.
The regulator dissipation is calculated using:
P
D
+
ǒ
V
I
* V
O
Ǔ
I
O
Power dissipation resulting from quiescent current is negligible.
regulator protection
The TPS763xx pass element has a built-in back diode that safely conducts reverse currents when the input voltage drops
below the output voltage (e.g., 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 TPS763xx also features internal current limiting and thermal protection. During normal operation, the TPS763xx limits
output current to approximately 800 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 165°C, thermal-protection
circuitry shuts it down. Once the device has cooled down to below 140°C, the regulator operation resumes.