FSEZ1016A Fairchild Semiconductor, FSEZ1016A Datasheet - Page 12

• Manufacturer Part Number: FSEZ1016A
• Description: This highly integrated PWM controller provides several features to enhance the performance of low-power flyback converters
• Manufacturer: Fairchild Semiconductor

© 2009 Fairchild Semiconductor Corporation
FSEZ1016A • Rev. 1.0.2
Protections
The FSEZ1016A has several self-protective functions,
such
Temperature
protection. All the protections are implemented as auto-
restart mode. When the auto-restart protection is
triggered, switching is terminated and the MOSFET
remains off. This causes V
the V
FSEZ1016A reduces to the startup current (maximum
10µA) and the current supplied startup resistor charges
the V
voltage of 16V, FSEZ1016A resumes normal operation.
In this manner, the auto-restart alternately enables and
disables the switching of the MOSFET until the fault
condition is eliminated (see Figure 29).
3.5mA
10µA
V
V
16V
5V
DS
DD
Operating Current
DD
DD
as
turn-off voltage of 5V, the current consumed by
Power
Figure 29. Auto-Restart Operation
capacitor. When V
On
Over-Voltage
Protection
Operation
Normal
Occurs
Fault
DD
Situation
Protection
Fault
(OTP),
to fall. When V
DD
Fault Removed
reaches the turn-on
and
(OVP),
Operation
Normal
DD
brownout
reaches
Over-
12
V
V
voltage conditions. If the V
open-feedback condition, OVP is triggered. The OVP
has a debounce time (typical 250µs) to prevent false
triggering by switching noise. It also protects other
switching devices from over voltage.
Over-Temperature Protection (OTP)
A built-in temperature-sensing circuit shuts down PWM
output if the junction temperature exceeds 140°C.
Brownout Protection
FSEZ1016A detects the line voltage using auxiliary
winding voltage since the auxiliary winding voltage
reflects the input voltage when the MOSFET is turned
on. The VS pin is clamped at 1.15V while the MOSFET
is turned on and brownout protection is triggered if the
current out of the VS pin is less than I
180μA) during the MOSFET conduction.
Pulse-by-Pulse Current Limit
When the sensing voltage across the current sense
resistor exceeds the internal threshold of 1.3V, the
MOSFET is turned off for the remainder of the switching
cycle. In normal operation, the pulse-by-pulse current
limit is not triggered since the peak current is limited by
the control loop.
DD
DD
Over-Voltage Protection (OVP)
over-voltage protection prevents damage from over-
DD
voltage exceeds 28V by
VS-UVP
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(typical