TLE8386-2EL Datasheet, PDF (9/32 Pages) Infineon Technologies AG – Basic Smart Boost Controller

TLE8386-2EL
5
Boost Regulator
5.1
Description
Boost Regulator
The TLE8386-2 boost (step-up) regulator provides a higher output voltage than input voltage. The PWM controller
measures the output voltage via a resistor divider connected between Pin FB and ground, and determines the
appropriate pulse width duty cycle (on time). An over voltage protection switches off the converter case if the
voltage at Pin FB exceeds the over voltage limit. If the connection to the output voltage resistor divider should be
lost, an internal current source connected to Pin FB will draw the voltage above this limit and shut the external
MOSFET off. The current mode controller has a built-in slope compensation to prevent sub-harmonic oscillations
which is a characteristic of current mode controllers operating at high duty cycles (>50% duty). An additional built-
in feature is an integrated soft start that limits the current through the inductor and the external power switch during
initialization.
The soft-start time T_SS is adjustable using an external capacitor C_SST:
T_SS = C_SST × ^2-1---,_0-0--µ-0---A-V--
The switching frequency may be adjusted by using an external resistor (please refer to chapter Oscillator and
Synchronization). If synchronization to an external frequency source is used, the internal frequency has to be
adjusted close to this external source.
SYNC ¹⁰
Synchroni
zation
FREQ ¹¹
Oscillator
Slope
Comp.
VIVCC
SQ
R /Q
Temp.
Sensor
Soft
Start
PWM Curr
Comparator
Logic
D
Gate
Driver
2 _SWO
Over Voltage
Comparator
VOVFB,TH
SST ⁵
Soft Start
COMP 8
Figure 3 Boost Regulator Block Diagram
Data Sheet
Current Sense
OTA
+
-
4 _SWCS
3 _SGND
gm_EA
Feedback Error
Amplifier
Boost_Diag .vsd
6 _FB
VRef
9
Rev. 1.0, 2010-10-25