VIPER22AS-E STMicroelectronics, VIPER22AS-E Datasheet - Page 8

• Manufacturer Part Number: VIPER22AS-E
• Description: IC OFFLINE SWIT PWM SMPS 8SOIC
• Manufacturer: STMicroelectronics
• Series: VIPER™r

Specifications of VIPER22AS-E

• Output Isolation: Isolated
• Frequency Range: 54 ~ 66kHz
• Voltage - Input: 8 ~ 50 V
• Voltage - Output: 730V
• Power (watts): 7W
• Operating Temperature: 25°C ~ 125°C
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Output Power: 12 W, 7 W
• Input Voltage: 9 V to 38 V
• Switching Frequency: 60 KHz
• Operating Temperature Range: - 40 C to + 150 C
• Mounting Style: SMD/SMT
• Output Voltage: 730V
• No. Of Outputs: 1
• Power Dissipation Pd: 7W
• Supply Voltage Range: 9V To 38V
• No. Of Pins: 8
• For Use With: 497-9049 - BOARD EVAL BASED VIPER22ASTR-E497-8215 - BOARD EVAL BASED ON VIPER22A497-5864 - EVAL BOARD DUAL OUTPUT VIPER22A497-5071 - EVAL BOARD DIMMABLE HB PWR LEDVIPER22-LED-EV - VIPER LED POWER SUPPLY
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6800-5; VIPER22AS-E

Operations
4.3
8/20
Feedback Pin Principle of Operation
A feedback pin controls the operation of the device. Unlike conventional PWM control
circuits which use a voltage input (the inverted input of an operational amplifier), the FB pin
is sensitive to current.
Figure 4.
The Power MOSFET delivers a sense current I
R2 receives this current and the current coming from the FB pin. The voltage across R2 is
then compared to a fixed reference voltage of about 0.23V. The MOSFET is switched off
when the following equation is reached:
As soon as the device starts switching, it immediately receives some energy from the
auxiliary winding. C5 can be therefore reduced and a small ceramic chip (100nF) is
sufficient to insure the filtering function. The total start up time from the switch on of input
voltage to output voltage presence is dramatically decreased.
The output current characteristic can be maintained even with very low or zero output
voltage. Since the TSM101 is also supplied in forward mode, it keeps the current
regulation up whatever the output voltage is.The V
the input voltage, that is to say with a ratio of about 4 for a wide range application.
Internal current control structure
Figure 4.
presents the internal current mode structure.
R
2
⋅
(
Rev1
I
S
+
I
FB
)
s
=
which is proportional to the main current Id.
0.23V
DD
pin voltage may vary as much as
VIPer22ADIP/ VIPer22AS - E