TDA4863 Datasheet, PDF (11/27 Pages) Infineon Technologies AG – Boost Controller

TDA4863
Functional Description
To prevent false tripping the zero current detector is designed as a Schmitt-Trigger with
a hysteresis of 0.5 V. An internal 5 V clamp protects the input from overvoltage
breakdown, a 0.6 V clamp prevents substrate injection. An external resistor has to be
used in series with the auxiliary winding to limit the current through the clamps.
2.8
Restart Timer
The restart timer function eliminates the need of an oscillator. The timer starts or restarts
the TDA4863 when the driver output has been off for more than 150 µs after the inductor
current reaches zero.
2.9
Undervoltage Lockout
An undervoltage lockout circuitry switches the IC on when V_CC reaches the upper
threshold V_CCH and switches the IC off when V_CC is falling below the lower threshold V_CCL.
During start up the supply current is less then 100 µA.
An internal voltage clamp has been added to protect the IC from V_CC overvoltage
condition. When using this clamp special care must be taken on power dissipation.
Start up current is provided by an external start up resistor which is connected from the
AC line to the input supply voltage V_CC and a storage capacitor which is connected from
V_CC to ground. Be aware that this capacitor is discharged before the IC is plugged into
the application board. Otherwise the IC can be destroyed due to the high capacitor
voltage.
Bootstrap power supply is created with the previous mentioned auxiliary winding and a
diode (see “Application Circuit” on Page 21).
2.10
Gate Drive
The TDA4863 totem pole output stage is MOSFET compatible. An internal protection
ciruitry is activated when V_CC is within the start up phase and ensures that the MOSFET
is turned off. The totem pole output has been optimized to minimize cross conduction
current during high speed operation.
Data Sheet
11
V1.0, 2003-05