TOP242R POWERINT [Power Integrations, Inc.], TOP242R Datasheet - Page 11

• Manufacturer Part Number: TOP242R
• Description: TOPSwitch -GX Family Extended Power, Design Flexible, EcoSmart, Integrated Off-line Switcher
• Manufacturer: POWERINT [Power Integrations, Inc.]

Using Feature Pins
FREQUENCY (F) Pin Operation
The FREQUENCY pin is a digital input pin available in the
Y, R or F package only. Shorting the FREQUENCY pin to
SOURCE pin selects the nominal switching frequency of
132 kHz (Figure 13) which is suited for most applications. For
other cases that may benefit from lower switching
frequency such as noise sensitive video applications, a 66 kHz
switching frequency (half frequency) can be selected by
shorting the FREQUENCY pin to the CONTROL pin
(Figure 14). In addition, an example circuit shown in Figure 15
may be used to lower the switching frequency from 132 kHz in
normal operation to 66 kHz in standby mode for very low standby
power consumption.
LINE-SENSE (L) Pin Operation (Y, R and F Packages)
When current is fed into the LINE-SENSE pin, it works as a
voltage source of approximately 2.6 V up to a maximum
current of +400 µA (typical). At +400 µA, this pin turns into a
constant current sink. Refer to Figure 12a. In addition, a
comparator with a threshold of 1 V is connected at the pin and is
used to detect when the pin is shorted to the SOURCE pin.
There are a total of four functions available through the use of
the LINE-SENSE pin: OV, UV, line feed forward with DC
reduction, and remote ON/OFF. Connecting the LINE-SENSE
pin to the SOURCE pin disables all four functions. The LINE-
SENSE pin is typically used for line sensing by connecting a
resistor from this pin to the rectified DC high voltage bus to imple-
ment OV, UV and DC
mode, the value of the resistor determines the line OV/UV thresh-
olds, and the DC
voltage starting from just above the UV threshold. The pin can
also be used as a remote on/off and a synchronization input. Refer
to Table 2 for possible combinations of the functions with
Table 2. Typical LINE-SENSE and EXTERNAL CURRENT LIMIT Pin Configurations.
*This table is only a partial list of many LINE-SENSE and EXTERNAL CURRENT LIMIT pin configurations that are possible.
Three Terminal Operation
Under-Voltage
Overvoltage
Line Feed Forward (DC
Overload Power Limiting
External Current Limit
Remote ON/OFF
Figure Number
MAX
is reduced linearly with rectified DC high
LINE-SENSE AND EXTERNAL CURRENT LIMIT PIN TABLE*
MAX
reduction with line voltage. In this
MAX
)
16
17
18
19
MAX
20
example circuits shown in Figure 16 through Figure 40. A
description of specific functions in terms of the LINE-SENSE
pin I/V characteristic is shown in Figure 11 (right hand side).
The horizontal axis represents LINE-SENSE pin current with
positive polarity indicating currents flowing into the pin. The
meaning of the vertical axes varies with functions. For those
that control the on/off states of the output such as UV, OV and
remote ON/OFF, the vertical axis represents the enable/
disable states of the output. UV triggers at I
with 30 µA hysteresis) and OV triggers at I
typical with 8 µA hysteresis). Between the UV and OV thresh-
olds, the output is enabled. For line feed forward with DC
reduction, the vertical axis represents the magnitude of the
DC
maximum duty cycle from 78% at I
38% at I
EXTERNAL CURRENT LIMIT (X) Pin Operation
(Y, R and F Packages)
When current is drawn out of the EXTERNAL CURRENT
LIMIT pin, it works as a voltage source of approximately
1.3 V up to a maximum current of –240 µA (typical). At
–240 µA, it turns into a constant current source (refer to
Figure 12a).
There are two functions available through the use of the
EXTERNAL CURRENT LIMIT pin: external current limit
and remote ON/OFF. Connecting the EXTERNAL CURRENT
LIMIT pin and SOURCE pin disables the two functions. In
high efficiency applications this pin can be used to reduce the
current limit externally to a value close to the operating peak
current, by connecting the pin to the SOURCE pin through a
resistor. The pin can also be used as a remote on/off. Table 2
shows several possible combinations using this pin. See
21
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. Line feed forward with DC
OV
22
(+225 µA).
23
24
25
26
L(DC)
TOP242-250
MAX
(+60 µA typical) to
27
UV
reduction lowers
(+50 µA typical
OV
28
1/02
(+225 µA
G
29
11
MAX