TLE4253 Datasheet, PDF (17/22 Pages) Infineon Technologies AG – Low Dropout Voltage Tracking Regulator

TLE4253
Application Information
VBAT
Main µC supply, e.g.
I
TLE4271-2 Q
TLE4278
TLE4470
etc.
GND
µC, e.g. C167
VDD
I/O
VREF
R1_ADJ
R2_ADJ
EN/
5 ADJ
1
Q
TLE 4253 G
I
8
GND
2, 3, 6, 7
4
FB
VQ < VREF
Figure 4 Application circuit: Output voltage V_Q lower than reference voltage V_REF
In order to obtain a lower output voltage V_Q at the tracker output than the reference voltage V_REF, a voltage divider
according to Figure 4 has to be used. The output voltage V_Q then calculates:
V_Q
=
V_R
E
F
⋅


R-----1---_A^----_D^R----_J^2---+^{-A---D-R---J-2---}_A^----_D^----_J^
With a given reference voltage V_REF, the desired output voltage V_Q and the resistor value R1_ADJ, the resistor value
for R2_ADJ is given by:
R2_ADJ
=
R1_ADJ
⋅


V-----_R^----_E^-V--_F^---Q-–^----V-----_Q^{--}
Taking into consideration also the effect of the internal EN/ADJ pull-down resistor, the external resistor divider’s
R2_ADJ has to be selected to:
R 2 _{A D J ,s e l e c t}
=


-RR----_P-2--_u-^A-_l--_l-^D-_D--^J-_o---^â‹_w---R-_n---_,^P-_m--^u--_i-^ln-^l--^D-_–---^o--R^w----ⁿ_2---^,_A-^m---_D-ⁱ--ⁿ-_{J}
Data Sheet
17
Rev. 1.2, 2009-11-09