TLF1963 Datasheet, PDF (18/24 Pages) Infineon Technologies AG – Low Dropout Linear Voltage Post Regulator

TLF1963
Application Information
6
Application Information
Note: The following information is given as a hint for the implementation of the device only and shall not be
regarded as a description or warranty of a certain functionality, condition or quality of the device.
The TLF1963 is an 1.5 A low dropout regulator optimized for fast transient response. The device is capable of
supplying 1.5 A at a very low dropout voltage up to a Junction Temperature of 150 °C. The low operating quiescent
current of 1 mA drops to less than 1 µA in case the device is disabled. In addition to the low quiescent current, the
TLF1963 incorporates several protection features which make them ideal for use in battery-powered systems. The
device is protected against both reverse input and reverse output voltages.
Note: This is a very simplified example of an application circuit. The function must be verified in the real application.
VBat
2
I
10µF
TLF1963
Q4
VQ
10 µF
R2
5
ADJ
R1
EN
1
Figure 4 Application Diagram
GND
3
6.1
Adjustable Operation
The TLF1963 has an output voltage range of 1.21 V to V_I - V_dr < 20 V. The output voltage is set by the ratio of two
external resistors as shown in Figure 4. The device serves the output to maintain the voltage at the ADJ pin at
1.21 V referenced to ground. The current in R1 is then equal to 1.21 V / R1 and the current in R2 is the current in
R1 plus the ADJ pin bias current. The ADJ pin bias current, 1 µA at 25 °C, flows through R2 into the ADJ pin. The
output voltage can be calculated using the formula in Equation (1).
V_Q
=
V_ADJ
⋅
⎛
⎝
1
+
RR-----_{21-⎠⎞}
+ I_ADJ ⋅ R₂
(1)
V_ADJ = 1.21 V typical
I_ADJ = 1 µA at 25 °C
The value of R1 is recommended to be smaller than 12 kΩ to minimize errors in the output voltage caused by the
ADJ pin bias current. Note that in shutdown the output is turned off and the divider current will be zero.
The adjustable device is mainly tested and specified with the ADJ pin connected to the Q pin for an output voltage
of 1.21 V. Specifications for output voltages adjusted to greater values than 1.21V will be proportional to the ratio
of the desired output voltage to 1.21 V.
For example, load regulation for an output current change of 1 mA to 1.5 A is ΔV_Q,load = 2 mV typical at
V_Q,nom = 1.21 V.
At V_Q,nom = 5 V, load regulation is: ΔV_Q,load,5V = (5 V / 1.21 V)•(2 mV) = 8.3 mV
Data Sheet
18
Rev. 1.0, 2012-11-08