TDA8939TH Datasheet, PDF (5/21 Pages) NXP Semiconductors – Zero dead time Class-D 7.5 A power comparator

Philips Semiconductors
TDA8939
Zero dead time Class-D 7.5 A power comparator
Table 3:
Symbol
STAB1
V_SSP1
OUT1
BOOT1
V_DDP1
V_SSD
SUB
Pin description …continued
Pin
Description
19
decoupling internal stabilizer for logic supply channel 1
20
negative power supply voltage for channel 1
21
PWM output channel 1
22
bootstrap capacitor 1
23
positive power supply voltage for channel 1
24
negative digital supply voltage
-
heat spreader of package; internally connected to V_SSD
8. Functional description
8.1 General
The TDA8939 class-D power comparator is designed for use in fully digital open-loop
class-D audio applications. Excellent timing accuracy with respect to delay times and rise
and fall times is achieved and one of the most important sources of distortion in a full
digital open-loop audio amplifier is eliminated; the zero dead time switching concept is
included. The TDA8939 contains two independent class-D output stages with high power
D-MOS switches, drivers, timing and control logic. For protection a temperature sensor, a
maximum current detection and overvoltage detection circuit are integrated. An internal
protection latch keeps the power comparator in shut-down mode after a fault condition has
been detected. External reset of the latch is required via the enable input.
8.2 Protections
Overtemperature, overcurrent and overvoltage sensors are included in the TDA8939
power comparator. In the event that the maximum temperature, maximum current or
maximum supply voltage is exceeded the diagnostic output is activated (open-drain output
pulled-down via external pull-up resistor).
The diagnostic output pin is activated (active LOW) in case of:
1. Overtemperature (OTP): the junction temperature (T_j) exceeds a threshold level.
2. Overcurrent (OCP): the output current exceeds the maximum output current threshold
level (e.g. when the loudspeaker terminals are short-circuited it will be detected by the
current protection).
3. Overvoltage (OVP): the supply voltage applied to the power comparator exceeds the
maximum supply voltage threshold level.
The TDA8939 is self-protecting. If a fault condition (OTP, OCP or OVP) is detected it will
pull-down the diagnostic output (pin 7), while at the same time shutting down the power
stage. In case of a fault condition in one of the half-bridges or output channel the other
half-bridge and output channel will also shut down. All protections trigger a latch which
ensures that the power stage remains deactivated until the latch is reset again.
The latch is reset by switching the enable voltage of the power stage to LOW level. Both
set (S) and reset (R) inputs of the protection latch trigger on a negative falling slope.
9397 750 13023
Objective data sheet
Rev. 01 — 22 April 2004
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
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