VIPER53DIP-E ,Fixed frequency off line converterElectrical characteristics . . . . . 43 Pin connections and function . 74 Operation pictu ..
VIPER53DIP-E ,Fixed frequency off line converterapplications cover offline power supplies ■ Automatic burst mode in standby condition with a second ..
VIPER53DIP-E/ ,Fixed frequency off line converterAbsolute Maximum Ratings” table may cause permanent damage to the device. These are stress ratings ..
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VIPER53SP-E ,Fixed frequency off line converterElectrical characteristicsT = 25°C, V = 13V, unless otherwise specifiedJ DD Table 3. Power sectionS ..
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VIPER53DIP-E-VIPER53DIP-E/-VIPER53SP-E
Fixed frequency off line converter
November 2006 Rev 1 1/36
VIPer53 - EOFF-line primary switch
Features Switching frequency up to 300kHz Current limitation Current mode control with adjustable limitation Soft start and shut-down control Automatic burst mode in standby condition
(“Blue Angel“ compliant ) Undervoltage lockout with Hysteresis HIgh voltage star-tup current source Overtemperature protection Overload and short-circuit control
DescriptionThe VIPer53-E combines an enhanced current
mode PWM controller with a high voltage
MDMesh Power Mosfet in the same package.
Typical applications cover offline power supplies
with a secondary power capability ranging up to
30W in wide range input voltage, or 50W in single
European voltage range and DIP-8 package, with
the following benefits: Overload and short circuit controlled by
feedback monitoring and delayed device reset. Efficient standby mode by enhanced pulse
skipping. Primary regulation or secondary loop failure
protection through high gain error amplifier.
General features
Block diagram
Contents VIPer53 - E2/36
Contents Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.1 Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Pin connections and function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Operation pictures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Primary regulation configuration example . . . . . . . . . . . . . . . . . . . . . . 15 Secondary feedback configuration example . . . . . . . . . . . . . . . . . . . . 17 Current mode topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Standby mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 High voltage Start-up current source . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Short-circuit and overload protection . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Transconductance error amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Special recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Software implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
VIPer53 - E Electrical data 3/36
1 Electrical data
1.1 Maximum rating
Stressing the device above the rating listed in the “Absolute Maximum Ratings” table may
cause permanent damage to the device. These are stress ratings only and operation of the
device at these or any other conditions above those indicated in the Operating sections of
this specification is not implied. Exposure to Absolute Maximum Rating conditions for
extended periods may affect device reliability. Refer also to the STMicroelectronics SURE
Program and other relevant quality documents.
1.2 Thermal data
Table 1. Absolute maximum rating In order to improve the ruggedness of the device versus eventual drain overvoltages, a resistance of 1kΩ
should be inserted in series with the TOVL pin.\
Table 2. Thermal data When mounted on a standard single-sided FR4 board with 50mm² of Cu (at least 35 mm thick) connected
to the DRAIN pin. When mounted on a standard single-sided FR4 board with 50mm² of Cu (at least 35 mm thick) connected
to the device tab.
Electrical characteristics VIPer53 - E
4/36
2 Electrical characteristics
TJ = 25°C, VDD = 13V , unless otherwise specified
Table 3. Power section On clamped inductive load This parameter can be used to compute the energy dissipated at turn on Eton according to the initial drain
to source voltage VDSon and the following formula:
Table 4. Oscillator section
Eton 1--- CEon 3002 V DSon
300----------------⎝⎠⎛⎞1.5 ⋅=
VIPer53 - E Electrical characteristics 5/36
Table 5. Supply section
Table 6. Error amplifier section In order to insure a correct stability of the error amplifier, a capacitor of 10nF (minimum value: 8nF) should
always be present on the COMP pin.
Electrical characteristics VIPer53 - E
6/36
Table 9. Over temperature Protection Section
Table 7. PWM comparator section
Table 8. Overload protection section VCOMPovl is always lower than VCOMPhi
VIPer53 - E Pin connections and function 7/36 Pin connections and function
Figure 1. Pin connection (top view)
Figure 2. Current and voltage conventions
Pin connections and function VIPer53 - E
8/36
Table 10. Pin function
VIPer53 - E Operation pictures 9/36
4 Operation pictures
Figure 3. Rise and fall time
Figure 4. Overloaded event
Operation pictures VIPer53 - E
10/36
Figure 5. Start-up VDD current Figure 6. Blanking time
Figure 7. Thermal shutdown Figure 8. Overvoltage event
VIPer53 - E Operation pictures 11/36
Figure 9. Shutdown action Figure 10. Comp pin gain and offset
Figure 11. Output characteristics
Operation pictures VIPer53 - E
12/36
Figure 12. Oscillator schematic
The switching frequency settings shown on the graphic here below is valid within the
following boundaries:t > 2kΩ SW = 300kHz
Figure 13. Oscillator settings
VIPer53 - E Operation pictures 13/36
Figure 14. Error amplifier test cpfiguration
This configuration is for test purpose only. In order to insure a correct stability of the error
amplifier, a capacitor of 10nF (minimum value: 8nF) should be always connected between
COMP pin and ground. See figures Figure 18, 19 and 22.
Figure 15. Error amplifier transfer function
Operation pictures VIPer53 - E
14/36
Figure 16. Typical frequency variation vs. junction temperature
Figure 17. Typical current limitation vs. junction temperature
VIPer53 - E Primary regulation configuration example 15/36 Primary regulation configuration example
Figure 18. Off line power supply with auxiliary supply feedback
The schematic on Figure 18 delivers a fixed output voltage by using the internal error
amplifier of the device in a primary feedback configuration. The primary auxiliary winding
provides a voltage to the VDD pin, and is automatically regulated at 15V, due to the internal
error amplifier connected to this pin. The secondary voltage has to be adjusted through the
turn ratio of the transformer between auxiliary and secondary.
The error amplifier of the VIPer53 is a transconductance type: its output is a current
proportional to the difference of voltage between the VDD pin and the internally trimmed 15V
reference (i.e., the error voltage). As the transconductance value is set at a relatively low
value to control the overall loop gain and ensure stability, this current has to be integrated by
a capacitor (C7 in Figure 18). When the steady state operation is reached, this capacitor
blocks any DC current from the COMP pin and imposes a “nil” error voltage. Therefore, the
VDD voltage is accurately regulated to 15V.
This results in a good load regulation, which depends only on transformer coupling and
output diodes impedance. The current mode structure takes care of all incoming voltage
changes, thus providing at the same time an excellent line regulation.
Primary regulation configuration example VIPer53 - E
16/36
The switching frequency can be set to any value through the choice of R3 and C5. This
allows to optimize the efficiency of the converter by adopting the best compromise between
switching losses, EMI (Lower with low switching frequencies) and transformer size (Smaller
with high switching frequencies). For an output power of a few watts, typical switching
frequencies between 20kHz and 40kHz because of the small size of the transformer. For
higher power, 70kHz to 130kHz are generally chosen.
The R5 compensation resistor value sets the dynamic behavior of the converter. It can be
adjusted to provide the best compromise between stability and recovery time with fast load
changes.
VIPer53 - E Secondary feedback configuration example 17/36 Secondary feedback configuration example
When a more accurate output voltage is needed, the way is to monitor it directly secondary
side, and drive the PWM controller through an optocoupler as shown on Figure 17.
The optocoupler is connected in parallel with the compensation network on the COMP pin.
The design of the auxiliary winding that the VDD voltage is always lower than the internal
15V reference. The internal error amplifier will therefore be saturated in the high state, and
because of its transconductance nature, will deliver a constant biasing current of 0.6mA to
the optotransistor. This current does not depend on the compensation voltage, and so it
does not depend on the output load either. Consequently, the gain of the optocoupler
ensures consequently a constant biasing of the TL431 device (U3) which is in charge of
secondary regulation. If the optocoupler gain is sufficiently low, no additional components
are required to ensure a minimum current biasing of U3. Also, the low biasing current value
avoid any ageing of the optocoupler.
The constant current biasing can be used to simplify the secondary circuit: Instead of a
TL431, a simple zener and resistance network in series with the optocoupler diode can
insure a good secondary regulation. As the current flowing in this branch remains constant
for the same reason as above, typical load regulation of 1% can be achieved from zero to full
output current with this simple configuration.
Figure 19. Off line power supply with optocoupler feedback
Secondary feedback configuration example VIPer53 - E
18/36
Since the dynamic characteristics of the converter are set on the secondary side through
components associated to U3, the compensation network has only a role of gain
stabilization for the optocoupler, and its value can be freely chosen. R5 can be set to a fixed
value of 1kΩ , offering the possibility of using C7 as a soft start capacitor: When starting up
the converter, the VIPer53 device delivers a constant current of 0.6 mA on the COMP pin,
creating a constant voltage of 0.6V in R5 and a rising slope across C7. This voltage shape,
together with the operating range of 0.5V to 4.5V provides a soft start-up of the converter.
The rising speed of the output voltage can be set through the value of C7. The C4 and C6
values must be adjusted accordingly in order to ensure a correct start-up.
