TLD5541-1QV Datasheet, PDF (29/82 Pages) Infineon Technologies AG – H-Bridge DC/DC Controller with SPI Interface

H-Bridge DC/DC Controller with SPI Interface
TLD5541-1QV
Regulator Description
switches (to short the LEDs) for the new Light configuration, after the Final V_OUT is reached and before the normal
switching activity would again raise the output voltage. See Figure 16.
The Preparation time has to be sufficient for the capacitors C_OUT and C_COMP to be discharged to the desired value.
The C_OUT discharge time depends heavily on: I_DISCH, C_OUT size, V_OUT Initial, V_OUTFinal and V_IN, so all those values
have to be considered when setting the preparation time. In order to set a preparation time on the TLD5541-1QV,
a SPI command has to be sent to the register MFSSETUP2.MFSDLY).
The Equation (5) below describes the relationship between the switching frequency f_SW and the
MFSSETUP2.MFSDLY register value.
[ ] t _prep
=
1
f _SW
⋅
2 + (MFSDLY )_dec
(5)
For SPI command details refer to Chapter 12.6.
Fast Discharge Phase
After programming the desired output voltage Ratio via SPI , the right Preparation Time and activating the state
machine (MFSSETUP1.SOMFS = HIGH) the TLD5541-1QV inverts the inductor current I_L and keeps it at the switch
current limit I_SwLim until the V_OUT reaches the desired target.
I = ^V _{R SwLim}
SWCS _ boost
SWCS
(6)
Figure 16 displays the relation of inductor current I_L and the output voltage V_OUT during a fast output discharge
operation mode.
Data Sheet
29
Rev. 1.0, 2016-05-20