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PDF T0P249 Datasheet ( Hoja de datos )

Número de pieza T0P249
Descripción (T0P242 - T0P2439) Family Extended Power
Fabricantes Power Integrations 
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T0P249 datasheet

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T0P249 pdf
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TOP242-249
TOPSwitch-GX Family Functional Description
Like TOPSwitch, TOPSwitch-GX is an integrated switched
mode power supply chip that converts a current at the control
input to a duty cycle at the open drain output of a high voltage
power MOSFET. During normal operation the duty cycle of the
power MOSFET decreases linearly with increasing CONTROL
pin current as shown in Figure 7.
In addition to the three terminal TOPSwitch features, such as the
high voltage start-up, the cycle-by-cycle current limiting, loop
compensation circuitry, auto-restart, thermal shutdown, the
TOPSwitch-GX incorporates many additional functions that
reduce system cost, increase power supply performance and
design flexibility. A patented high voltage CMOS technology
allows both the high voltage power MOSFET and all the low
voltage control circuitry to be cost effectively integrated onto a
single monolithic chip.
Three terminals, FREQUENCY, LINE-SENSE, and
EXTERNAL CURRENT LIMIT (available in Y or R package)
or one terminal MULTI-FUNCTION (available in P or G
Package) have been added to implement some of the new
functions. These terminals can be connected to the SOURCE
pin to operate the TOPSwitch-GX in a TOPSwitch-like three
terminal mode. However, even in this three terminal mode, the
TOPSwitch-GX offers many new transparent features that do
not require any external components:
1. A fully integrated 10 ms soft-start limits peak currents and
voltages during start-up and dramatically reduces or
eliminates output overshoot in most applications.
2. DCMAX of 78% allows smaller input storage capacitor, lower
input voltage requirement and/or higher power capability.
3. Frequency reduction at light loads lowers the switching
losses and maintains good cross regulation in multiple
output supplies.
4. Higher switching frequency of 132 kHz reduces the
transformer size with no noticeable impact on EMI.
5. Frequency jittering reduces EMI.
6. Hysteretic over-temperature shutdown ensures automatic
recovery from thermal fault. Large hysteresis prevents circuit
board overheating.
7. Packages with omitted pins and lead forming provide large
drain creepage distance.
8. Tighter absolute tolerances and smaller temperature vari-
ations on switching frequency, current limit and PWM gain.
The LINE-SENSE (L) pin is usually used for line sensing by
connecting a resistor from this pin to the rectified DC high
voltage bus to implement line overvoltage (OV), under-voltage
(UV) and line feed forward with DCMAX reduction. In this
mowdew, twhe.vDalauetaofSthheereesist4toUr d.ecteormmines the OV/UV thresholds
and the DCMAX is reduced linearly starting from a line voltage
above the under-voltage threshold. See Table 2 and Figure 11.
Auto-restart
ICD1
132
IB
IL = 190 µA
IL = 125 µA
IL < IL(DC)
30
Auto-restart
ICD1
78
IC (mA)
IB
Slope = PWM Gain
38 IL = 125 µA
10 IL = 190 µA
IL < IL(DC)
TOP242/5 1.6 2.0
5.2 6.0
TOP246/9 2.2 2.6
5.8 6.6
IC (mA)
Note: For P and G packages IL is replaced with IM.
PI-2633-060500
Figure 7. Relationship of Duty Cycle and Frequency to CONTROL
Pin Current.
The pin can also be used as a remote ON/OFF and a
synchronization input.
The EXTERNAL CURRENT LIMIT (X) pin is usually used to
reduce the current limit externally to a value close to the operating
peak current, by connecting the pin to SOURCE through a
resistor. This pin can also be used as a remote ON/OFF and a
synchronization input in both modes. See Table 2 and Figure 11.
For the P or G packages the LINE-SENSE and EXTERNAL
CURRENT LIMIT pin functions are combined on one MULTI-
FUNCTION (M) pin. However, some of the functions become
mutually exclusive as shown in Table 3.
The FREQUENCY (F) pin in the Y or R package sets the
switching frequency to the default value of 132 kHz when
connected to SOURCE pin. A half frequency option of 66 kHz
can be chosen by connecting this pin to CONTROL pin instead.
Leaving this pin open is not recommended.
August 8, 2000
5E
7/01

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T0P249 arduino
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Using Feature Pins
FREQUENCY (F) Pin Operation
The FREQUENCY pin is a digital input pin available in the
Y or R 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 and R 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 DCMAX
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
implement OV, UV and DCMAX reduction with line voltage. In
this mode, the value of the resistor determines the line OV/UV
thresholds, and the DC is reduced linearly with rectified DC
MAX
high voltage starting from just above the UV threshold. The pin
can also be used as a remote on/off and a synchronization input.
TOP242-249
Refer to Table 2 for possible combinations of the functions with
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 IUV (+50 µA typical with
30 µA hysteresis) and OV triggers at I (+225 µA typical with
OV
8 µA hysteresis). Between the UV and OV thresholds, the
output is enabled. For line feed forward with DCMAX reduction,
the vertical axis represents the magnitude of the DCMAX. Line
feed forward with DCMAX reduction lowers maximum duty cycle
from 78% at I (+60 µA typical) to 38% at I (+225 µA).
L(DC)
OV
EXTERNAL CURRENT LIMIT (X) Pin Operation
(Y and R 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 Figure
LINE-SENSE AND EXTERNAL CURRENT LIMIT PIN TABLE*
Figure Number
16 17 18 19 20 21 22 23 24 25 26 27 28 29
Three Terminal Operation
Under-Voltage
✔✔
✔✔✔
Overvoltage
✔✔
✔✔✔
Line Feed Forward (DC )
MAX
Overload Power Limiting
✔✔✔
External Current Limit
✔✔
✔✔
✔✔
Remote ON/OFF
✔✔ ✔ ✔ ✔ ✔
*Twhiws tawbl.eDisaontalySa phaertiealtli4stUof.mcaonmy LINE-SENSE and EXTERNAL CURRENT LIMIT pin configurations that are possible.
Table 2. Typical LINE-SENSE and EXTERNAL CURRENT LIMIT Pin Configurations.
August 8, 2000
11E
7/01

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