TEA1716T
NXP Semiconductors
Resonant power supply control IC with PFC
yes
Restart request
no
V
u(RCPROT)
V
RCPROT
V
l(RCPROT)
0
passed
Restart time
t
014aaa854
Fig 6. Operation of the restart timer
Figure 6 shows the operation of the restart timer. Normally Cprot is discharged to 0 V.
When a restart is requested, Cprot is quickly charged to the upper switching level
V
R
V
u(RCPROT). Then the RCPROT pin becomes high ohmic and Cprot discharges through
prot. The restart time has elapsed when VRCPROT reaches the lower switching level
l(RCPROT) (0.5 V typical). The IC then restarts and Cprot is discharged.
7.5.3 Fast shutdown reset (pin SNSMAINS)
The latched Protection shut-down state is reset when VSUPIC and VSUPHV drop below their
respective reset levels, Vrst(SUPIC) and Vrst(SUPHV). Typically, the PFC boost capacitor,
C
boost, requires a discharge before VSUPIC and VSUPHV drop below their reset levels, which
can take a long time.
Fast shut-down reset facilitates a faster reset. When the mains supply is interrupted, the
voltage on pin SNSMAINS drops. When VSNSMAINS falls below Vrst(SNSMAINS) and then
rises again by a hysteresis value, the IC leaves the Protection shut-down state. The boost
capacitor Cboost does not have to be discharged to initiate a new start-up.
The Protection shut-down state can also be ended by pulling down the enable input (pin
SSHBC/EN).
7.5.4 Output overvoltage protection, OVP-output (pin SNSOUT)
The TEA1716 outputs are provided with overvoltage protection (OVP-output; see
Section 7.9). The output voltage can be measured via the auxiliary winding of the
resonant transformer. This voltage can be sensed at the SNSOUT pin via an external
rectifier and resistive divider. An overvoltage is detected when the SNSOUT voltage
exceeds Vovp(SNSOUT) (3.5 V typical). Once an overvoltage has been detected, the
TEA1716 enters the Protection shut-down state.
Additional external protection circuits, such as an external overtemperature protection
circuit, can be connected to this pin. Connect them to pin SNSOUT via a diode so that the
error condition triggers an OVP event.
7.5.5 Output failed start protection, FSP-output (pin SNSOUT)
The TEA1716 outputs are provided with failed start protection (FSP output;
see Section 7.9). During start-up, the output voltage is below Vfsp(SNSOUT) for a time. This
is not an error condition if does not last longer than expected. For this reason, the
protection timer is started when VSNSOUT is below Vfsp(SNSOUT) (2.5 V typical) during
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
14 of 46
ETC [ ETC ]
