TEA1716T
NXP Semiconductors
Resonant power supply control IC with PFC
7.5.2 Protection and restart timer
The TEA1716 contains a programmable timer which can be used for timing several
protection functions. The timer can be used in two ways - as a protection timer and as a
restart timer. The timing of the timers can be set independently via an external resistor
R
prot and capacitor Cprot connected to pin RCPROT.
7.5.2.1 Protection timer
Certain error conditions can be allowed to persist for a time before protective action is
required. The protection timer defines the protection period - how long the error is allowed
to persist before the protection function is triggered. The protection functions that use the
protection timer can be found in the protection overview in Section 7.9.
short
error
long
error
repetative
error
present
Error
none
I
ch(slow)(RCPROT)
I
RCPROT
0
V
u(RCPROT)
V
RCPROT
0
passed
Protection time
t
014aaa853
Fig 5. Operation of the protection timer
Figure 5 shows the operation of the protection timer. When an error condition occurs, a
fixed current Ich(slow)(RCPROT) (100 A typical) flows out of the RCPROT pin and charges
C
prot. Rprot causes the voltage to rise exponentially. The protection time has elapsed when
the voltage on RCPROT reaches the upper switching level Vu(RCPROT) (4 V typical). At this
instant, the appropriate protective action is taken and Cprot is discharged.
If the error condition is removed before the voltage on RCPROT reaches Vu(RCPROT), Cprot
is discharged via Rprot and no action is taken.
The voltage on RCPROT can be raised above Vu(RCPROT) by an external circuit to force a
restart.
7.5.2.2 Restart timer
Certain error conditions require that the IC is disabled, particularly when the error
condition can cause components to overheat. In such cases, the IC must be disabled to
allow the power supply to cool down, before restarting automatically. The restart timer
determines the restart time. The restart timer is active in the Restart state. The protection
functions that trigger a restart can be found in the protection overview in Section 7.9.
TEA1716T
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
Objective data sheet
Rev. 1 — 27 January 2012
13 of 46
ETC [ ETC ]
