VIPER28HN STMicroelectronics, VIPER28HN Datasheet - Page 25

• Manufacturer Part Number: VIPER28HN
• Description: IC OFFLINE CONV PWM OVP 8DIP
• Manufacturer: STMicroelectronics
• Series: VIPer™ plusr

Specifications of VIPER28HN

• Output Isolation: Isolated
• Frequency Range: 103 ~ 127kHz
• Voltage - Input: 8.5 ~ 23.5 V
• Voltage - Output: 800V
• Power (watts): 20W
• Operating Temperature: -25°C ~ 125°C
• Package / Case: 8-DIP (0.300", 7.62mm), 7 Leads
• Output Voltage: 800 V
• Output Power: 1 W
• Input Voltage: - 0.3 V
• Switching Frequency: 115 KHz
• Operating Temperature Range: - 40 C to + 150 C
• Mounting Style: Through Hole
• Duty Cycle (max): 80 %
• Number Of Outputs: 1
• For Use With: 497-8840 - EVAL BOARD FOR VIPER28LD 60KHZ497-8839 - EVAL BOARD FOR VIPER28HD 115KHZ
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-8391-5

VIPER28
7.13
2
The
secondary winding or a hard-saturation of fly-back transformer. Such as anomalous
condition is invoked when the drain current exceed the threshold I
page 7
To distinguish a real malfunction from a disturbance (e.g. induced during ESD tests) a
“warning state” is entered after the first signal trip. If in the subsequent switching cycle the
signal is not tripped, a temporary disturbance is assumed and the protection logic will be
reset in its idle state; otherwise if the I
switching cycles a real malfunction is assumed and the power MOSFET is turned OFF.
The shutdown condition is latched as long as the device is supplied. While it is disabled, no
energy is transferred from the auxiliary winding; hence the voltage on the V
decays till the V
The start up HV current generator is still off, until V
V
and the converter switching restarts if the V
the device enters in auto-restart mode. This behavioral results in a low-frequency
intermittent operation (Hiccup-mode operation), with very low stress on the power circuit.
See the timing diagram of
Figure 27. Hiccup-mode OCP: timing diagram
DD(RESTART)
V
nd
DD
VIPER28
(RESTART)
I
V
DRAIN
level overcurrent protection and hiccup mode
V
V
Vcc
DRAIN
V
.
DD
DD
I
DMAX
DD
on
off
. After this condition the V
is protected against short-circuit of the secondary rectifier, short-circuit on the
DD
under voltage threshold (V
Secondary diode is shorted here
Secondary diode is shorted here
Figure 32
Doc ID 15028 Rev 4
.
DMAX
DD
capacitor is charged again by 600 µA current,
DDon
threshold is exceeded for two consecutive
DDoff
occurs. If the fault condition is not removed
), which clears the latch.
DD
voltage goes below its restart voltage,
DMAX
Operation descriptions
, see
DD
Table 8 on
capacitor
25/32
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