VIPER37LE STMicroelectronics, VIPER37LE Datasheet - Page 31

• Manufacturer Part Number: VIPER37LE
• Description: AC/DC Switching Converters ViperPlus Fixed Freq 800V 30mQ 265 Vac
• Manufacturer: STMicroelectronics
• Type: Off Line Switcherr

Specifications of VIPER37LE

• Product Category: AC/DC Switching Converters
• Input / Supply Voltage (max): 23.5 V
• Input / Supply Voltage (min): 8.5 V
• Switching Frequency: 60 kHz
• Supply Current: 2.5 mA
• Operating Temperature Range: - 40 C to + 150 C
• Mounting Style: Through Hole
• Package / Case: SDIP-10
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 25 C
• Number Of Outputs: 1
• Output Power: 25 W

VIPER37
8.13
In order to enable the brownout function, the BR pin voltage must be higher than the
maximum V
2
The device is protected against short-circuit of the secondary rectifier, short-circuit on the
secondary winding, or a hard-saturation of the flyback transformer. Such an anomalous
condition is invoked when the drain current exceeds the threshold I
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 is reset in
its idle state; otherwise, if the I
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 to the V
The startup HV current generator is still off, until the V
voltage, V
current, and the converter switching restarts if the V
removed the device enters auto-restart mode. This behavior results in a low-frequency
intermittent operation (hiccup-mode operation), with very low stress on the power circuit.
See the timing diagram of
Figure 34. Timing diagram: hiccup-mode OCP
nd
V
DD(RESTART)
V
V
V
level overcurrent protection and hiccup mode
I
I
DRAIN
DRAIN
DDon
DDoff
V
DMAX
DD
Normal operation
DD(RESTART)
DIS
DD
threshold (150 mV), see
undervoltage threshold (V
. After this condition the V
Figure 34
Hiccup-mode
Secondary diode
short circuit
Doc ID 022218 Rev 1
DMAX
.
threshold is exceeded for two consecutive switching
Table 8
DDoff
.
DD
), which clears the latch.
capacitor is charged again by a 600 µA
DDon
DD
occurs. If the fault condition is not
voltage goes below its restart
DMAX
Operation description
(see
DD
Table 8
capacitor
).
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