tea1713lt NXP Semiconductors, tea1713lt Datasheet - Page 26

• Manufacturer Part Number: tea1713lt
• Description: Resonant Power Supply Control Ic With Pfc
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TEA1713LT
Product data sheet
7.8.8.3 Soft start reset
7.8.9 HBC high-frequency protection, HFP-HBC (pin RFMAX)
Section 7.8.10.2
regulation.
The soft start capacitor is neither charged nor discharged during non-operation time in
Burst mode. The soft start voltage will not change during this time.
The TEA1713LT has a special fast soft start reset feature for the HBC controller that
forces V
enabled via the SSHBC/EN pin or after a restart to ensure a safe start at maximum
frequency. Soft start reset is not used when the operation was stopped in Burst mode.
When a soft start reset function is activated, the oscillator control input is disconnected
from the soft start capacitor, C
the switching frequency is immediately set to a maximum. Starting the switching at the
maximum is a safe starting condition. At the same time, the capacitor is discharged to the
maximum frequency level, V
oscillator control input is connected to the pin again and the normal soft start sweep
follows.
downwards.
Normally the converter will not operate continuously at maximum frequency because it will
sweep down to much lower values. Certain error conditions, such as a disconnected
transformer, could cause the converter to operate continuously at maximum frequency. If
zero-voltage switching conditions are no longer present, the MOSFETs can overheat. The
TEA1713LT features High-Frequency Protection (HFP) for the HBC controller to protect it
from being damaged in such circumstances.
Fig 16. Soft start reset and two-speed soft start
The slow (dis-)charge speed is used for the lower frequency range where V
above V
converter react strongly to frequency variations.
V
SSHBC/EN
Figure 16
fmax(ss)(RFMAX)
ss(hf-lf)(SSHBC)
V
All information provided in this document is subject to legal disclaimers.
Enable
ss(hf-lf)(SSHBC)
V
V
describes how the two-speed soft start function is used for overcurrent
fmax(SSHBC)
fmin(SSHBC)
shows the soft start reset and the two-speed frequency sweep
f
HB
on pin RFMAX. Soft start reset is used when the HBC controller is
f
f
max
(typ. 5.6 V). In the lower frequency range, the currents in the
min
Rev. 1 — 24 June 2011
on
off
0
0
fmax(SSHBC)
regulation
ss(HBC)
, connected between pin SSHBC/EN and ground and
. Once V
off
Resonant power supply control IC with PFC
forced
f
max
SSHBC/EN
sweep
fast
has reached this level, the
slow sweep
TEA1713LT
© NXP B.V. 2011. All rights reserved.
regulation
SSHBC/EN
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