SP000087990 Infineon Technologies, SP000087990 Datasheet - Page 8

• Manufacturer Part Number: SP000087990
• Manufacturer: Infineon Technologies

Specifications of SP000087990

• Start-up Supply Current: 50uA
• Switching Freq: 200kHz
• Operating Supply Voltage (min): 11V
• Operating Supply Voltage (max): 19V
• Operating Temp Range: -25C to 125C
• Operating Temperature Classification: Commercial
• Package Type: DSO
• Pin Count: 20
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Compliant

TDA 16888
2
Functional Description
Power Supply
The TDA 16888 is protected against overvoltages typically above 17.5 V by an internal
V
Zener diode Z3 at pin 9 (
) and against electrostatic discharging at any pin by special
CC
ESD circuitry.
By means of its power management the TDA 16888 will switch from internal stand-by,
which is characterized by negligible current consumption, to operation mode as soon as
a supply voltage threshold of 14 V at pin 9 (
V
) is exceeded. To avoid uncontrolled
CC
ringing at switch-over an undervoltage lockout is implemented, which will cause the
power management to switch from operation mode to internal stand-by as soon as the
supply voltage falls below a threshold of 11 V. Therefore, even if the supply voltage will
fall below 14 V, operation mode will be maintained as long as the supply voltage is well
above 11 V.
As soon as the supply voltage has stabilized, which is determined by the TDA 16888’s
power management and its soft-start feature at pin 13 (PWM SS), the PWM section will
be enabled by means of its internal bias control.
Protection Circuitry
Both PFC and PWM section are equipped with a fast overvoltage protection (C6)
sensing at pin 19 (PFC VS), which when being activated will immediately shut down both
gate drives. In addition to improve the PFC section’s load regulation it uses a fast but soft
overvoltage protection (OTA2) prior to the one described above, which when being
Q
activated will cause a well controlled throttling of the multiplier output
.
M
In case an undervoltage of the PFC output voltage is detected at pin 19 (PFC VS) by
comparator C4 the gate drive of the PWM section will be shut down in order to reduce
the load current and to increase the PFC output voltage. This undervoltage shutdown
has to be prior to the undervoltage lockout of the internal power management and
V
therefore has to be bound to a threshold voltage at pin 9 (
) well above 11 V.
CC
In order to prevent the external circuitry from destruction the PFC output PFC OUT
(pin 8) will immediately be switched off by comparator C2, if the voltage at pin 19
(PFC VS) drops to ground caused by a broken wire. In a similar way measures are taken
to handle a broken wire at any other pin in order to ensure a safe operation of the IC and
its adjoining circuitry.
If necessary both outputs, PFC OUT (pin 8) and PWM OUT (pin 10), can be shutdown
on external request. This is accomplished by shorting the external reference voltage at
V
pin 2 (
) to ground. To protect the external reference, it is equipped with a foldback
REF
V
characteristic, which will cut down the output current when
(pin 2) is shorted (see
REF
Figure 4).
Version 2.0
8
28 Feb 2000