Power Integrations TOP242-250 Technical data

PI-2632-060200

AC

IN

DC

OUT

D

S

C

TOPSwitch-GX

CONTROL

L

+

-

FX

查询TOP250Y/F供应商查询TOP250Y/F供应商

TOP242-250

TOPSwitch-GX Family

Extended Power, Design Flexible,

EcoSmart

Lower System Cost, High Design Flexibility

• Extended power range for higher power applications

• No heatsink required up to 34 W using P/G packages

• Features eliminate or reduce cost of external components

• Fully integrated soft-start for minimum stress/overshoot

• Externally programmable accurate current limit

• Wider duty cycle for more power, smaller input capacitor

• Separate line sense and current limit pins on Y/R/F packages

• Line under-voltage (UV) detection: no turn off glitches

• Line overvoltage (OV) shutdown extends line surge limit

• Line feed-forward with maximum duty cycle (DC

• Frequency jittering reduces EMI and EMI filtering costs

• Regulates to zero load without dummy loading

• 132 kHz frequency reduces transformer/power supply size

• Half frequency option in Y/R/F packages for video applications

• Hysteretic thermal shutdown for automatic fault recovery

• Large thermal hysteresis prevents PC board overheating

EcoSmart

• Extremely low consumption in remote off mode

• Frequency lowered with load for high standby efficiency

• Allows shutdown/wake-up via LAN/input port

Description

TOPSwitch-GX uses the same proven topology as TOPSwitch,
cost effectively integrating the high voltage power MOSFET,
PWM control, fault protection and other control circuitry onto
a single CMOS chip. Many
reduce system cost and improve design flexibility, performance
and energy efficiency.

Depending on package type, either 1 or 3 additional pins over
the TOPSwitch standard DRAIN, SOURCE and CONTROL
terminals allow the following functions: line sensing (OV/UV,
line feed-forward/DC
current limit, remote ON/OFF, synchronization to an external
lower frequency, and frequency selection (132 kHz/66 kHz).

All package types provide the following transparent features:
Soft-start, 132 kHz switching frequency (automatically reduced
at light load), frequency jittering for lower EMI, wider DC
hysteretic thermal shutdown, and larger creepage packages. In
addition, all critical parameters (i.e. current limit, frequency,
PWM gain) have tighter temperature and absolute tolerances
to simplify design and optimize system cost.

November 2005

®

®

, Integrated Off-line Switcher

Product Highlights

reduction rejects line ripple and limits DC

– Energy Efficient

(80 mW at 110 VAC, 160 mW at 230 VAC)

new functions are integrated to

reduction), accurate externally set

MAX

MAX

MAX

at high line

)

Figure 1. Typical Flyback Application.

OUTPUT POWER TABLE

Open

Frame

15 W
22 W
22 W
25 W
45 W
45 W
28 W
50 W
65 W
30 W
57 W
85 W
34 W
64 W

125 W

70 W

165 W

75 W

205 W

79 W

250 W

82 W

290 W

4

Adapter

2

6.5 W

85-265 VAC

1

Frame

11 W

7 W

9 W
17 W
15 W
11 W
20 W
20 W
13 W
23 W
26 W
15 W
26 W
40 W
28 W
55 W

125 W
30 W
70 W

155 W
31 W
80 W

180 W
32 W
90 W

210 W

Open

2

10 W
14 W
14 W
15 W
23 W
30 W
20 W
28 W
45 W
22 W
33 W
60 W
26 W
38 W
90 W
43 W

48 W

53 W

55 W

MAX

230 VAC ±15%

PRODUCT

TOP242 P or G

TOP242 R

TOP242 Y or F

TOP243 P or G

TOP243 R

TOP243 Y or F

TOP244 P or G

TOP244 R

TOP244 Y or F

TOP245 P or G

TOP245 R

TOP245 Y or F

TOP246 P or G

TOP246 R

TOP246 Y or F

TOP247 R

TOP247 Y or F

TOP248 R

TOP248 Y or F

TOP249 R

TOP249 Y or F

TOP250 R

TOP250 Y or F

Table 1. Notes: 1. Typical continuous power in a non-ventilated enclosed

,

adapter measured at 50
power in an open frame design at 50 °C ambient. See Key Applications
for detailed conditions. 3. For lead-free package options, see Part
Ordering Information. 4. 230 VAC or 100/115 VAC with doubler.

3

Adapter

1

9 W
15 W
10 W
13 W
29 W
20 W
16 W
34 W
30 W
19 W
37 W
40 W
21 W
40 W
60 W
42 W
85 W
43 W

105 W

44 W

120 W

45 W

135 W

°C ambient. 2. Maximum practical continuous

TOP242-250

Section List

Functional Block Diagram ....................................................................................................................................... 3

Pin Functional Description ...................................................................................................................................... 4

TOPSwitch-GX

CONTROL (C) Pin Operation .................................................................................................................................. 6

Oscillator and Switching Frequency ........................................................................................................................ 6

Pulse Width Modulator and Maximum Duty Cycle .................................................................................................. 7

Light Load Frequency Reduction ............................................................................................................................ 7

Error Amplifier ......................................................................................................................................................... 7

On-Chip Current Limit with External Programmability ............................................................................................ 7

Line Under-Voltage Detection (UV) ......................................................................................................................... 8

Line Overvoltage Shutdown (OV) ........................................................................................................................... 8

Line Feed-Forward with DC

Remote ON/OFF and Synchronization ................................................................................................................... 9

Soft-Start ................................................................................................................................................................. 9

Shutdown/Auto-Restart ........................................................................................................................................... 9

Hysteretic Over-Temperature Protection ................................................................................................................. 9

Bandgap Reference .............................................................................................................................................. 10

High-Voltage Bias Current Source ........................................................................................................................ 10

Using Feature Pins ................................................................................................................................................... 10

FREQUENCY (F) Pin Operation ........................................................................................................................... 10

LINE-SENSE (L) Pin Operation ............................................................................................................................ 10

EXTERNAL CURRENT LIMIT (X) Pin Operation .................................................................................................. 11

MULTI-FUNCTION (M) Pin Operation .................................................................................................................. 11

Typical Uses of FREQUENCY (F) Pin

Typical Uses of LINE-SENSE (L) and EXTERNAL CURRENT LIMIT (X) Pins

Typical Uses of MULTI-FUNCTION (M) Pin

Application Examples .............................................................................................................................................. 20

A High Efficiency, 30 W, Universal Input Power Supply ........................................................................................ 20

A High Efficiency, Enclosed, 70 W, Universal Adapter Supply .............................................................................. 20

A High Efficiency, 250 W, 250-380 VDC Input Power Supply ............................................................................... 22

Multiple Output, 60 W, 185-265 VAC Input Power Supply .................................................................................... 23

Processor Controlled Supply Turn On/Off ............................................................................................................. 24

Key Application Considerations

TOPSwitch-II
TOPSwitch-FX
TOPSwitch-GX
TOPSwitch-GX

Quick Design Checklist .........................................................................................................................................

Design Tools ......................................................................................................................................................... 32

Product Specifications and Test Conditions

Typical Performance Characteristics

Part Ordering Information ....................................................................................................................................... 46

Package Outlines ..................................................................................................................................................... 47

Family Functional Description ....................................................................................................... 5

Reduction ..............................................................................................................8

MAX

...................................................................................................................... 14

...................................................... 15

........................................................................................................... 17

............................................................................................................................. 26

vs.

TOPSwitch-GX

vs.

TOPSwitch-GX

Design Considerations ............................................................................................................... 28

Layout Considerations ................................................................................................................. 30

.......................................................................................................................... 26

....................................................................................................................... 28

32

......................................................................................................... 33

.................................................................................................................... 40

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TOP242-250

PI-2639-060600

SHUTDOWN/

AUTO-RESTART

PWM

COMPARATOR

CLOCK

SAW

HALF
FREQ.

CONTROLLED

TURN-ON

GATE DRIVER

CURRENT LIMI

T

COMPARATOR

INTERNAL UV

COMPARATOR

INTERNAL
SUPPLY

5.8 V

4.8

V

SOURCE (S

)

SRQ

D

MAX

STOP

SOFT­START

-

+

CONTROL (C)

LINE-SENSE (L

)

EXTERNAL

CURRENT LIMIT (X)

FREQUENCY (F

)

-

+

5.8 V

1

V

I

FB

R

E

Z

C

V

C

+

-

LEADING

EDGE

BLANKING

÷ 8

1

HYSTERETIC

THERMAL

SHUTDOWN

SHUNT REGULATOR/

ERROR AMPLIFIER

+

-

DRAIN (D)

ON/OFF

SOFT

START

DC

MAX

V

BG

DC

MAX

V

BG

+ V

T

0

OV/UV

V

I (LIMIT)

CURRENT

LIMIT

ADJUST

LINE

SENSE

SOFT START

LIGHT LOAD
FREQUENCY
REDUCTION

STOP LOGIC

OSCILLATOR WITH JITTER

PI-2641-061200

SHUTDOWN/

AUTO-RESTART

PWM

COMPARATOR

CLOCK

SAW

CONTROLLED

TURN-ON

GATE DRIVE

R

CURRENT LIMI

T

COMPARATOR

INTERNAL UV

COMPARATOR

INTERNAL
SUPPLY

5.8 V

4.8

V

SOURCE (S

)

SRQ

D

MAX

STOP

SOFT-

START

-

+

CONTROL (C)

MULTI

-

FUNCTION (M

)

-

+

5.8 V

I

FB

R

E

Z

C

V

C

+

-

LEADING

EDGE

BLANKING

÷ 8

1

HYSTERETIC

THERMAL

SHUTDOWN

SHUNT REGULATOR/

ERROR AMPLIFIER

+

-

DRAIN (D)

ON/OFF

SOFT

START

DC

MAX

V

BG

DC

MAX

V

BG

+ V

T

0

OV/UV

V

I (LIMIT)

CURRENT

LIMIT

ADJUST

LINE

SENSE

SOFT START

LIGHT LOAD
FREQUENCY
REDUCTION

STOP LOGIC

OSCILLATOR WITH JITTER

Figure 2a. Functional Block Diagram (Y, R or F Package).

Figure 2b. Functional Block Diagram (P or G Package).

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TOP242-250

PI-2724-010802

Tab Internally

Connected to

SOURCE Pin

Y Package (TO-220-7C)

C

D

S

S

S

S

1 C

3 X
2 L

5 F
4 S

7 D

M

P Package (DIP-8B)

G Package (SMD-8B)

R Package (TO-263-7C)
F Package (TO-262-7C)

8

5

7

1

1 2 3 4 5 7
C L X S F D

4

2

3

X

PI-2629-092203

DC

Input

Voltage

+

-

D

S

C

CONTROL

L

R

IL

R

LS

12 kΩ

2

MΩ

VUV = IUV x R

LS

V

OV = IOV x RLS

For RLS = 2 MΩ

DC

MAX

@100 VDC = 78%

DC

MAX

@375 VDC = 38%

For

RIL = 12 kΩ

I

LIMIT

= 69%

See Figure 54b for
other resistor values
(R

IL

) to select different

I

LIMIT

values

VUV = 100 VDC
VOV = 450 VDC

PI-2509-040501

DC

Input

Voltage

+

-

D M

S

C

VUV = IUV x R

LS

V

OV = IOV x RLS

For RLS = 2 MΩ

VUV = 100 VDC
V

OV =

450 VDC

DC

MAX

@100 VDC = 78%

DC

MAX

@375 VDC = 38%

CONTROL

R

LS

2 MΩ

PI-2517-022604

DC

Input

Voltage

+

-

D M

S

C

For R

IL

= 12 kΩ

I

LIMIT

= 69%

CONTROL

R

IL

See Figures 54b, 55b
and 56b for other resistor
values (R

IL

) to select

different

I

LIMIT

values.

For R

IL

= 25 kΩ

I

LIMIT

= 43%

Pin Functional Description

DRAIN (D) Pin:

High voltage power MOSFET drain output. The internal
start-up bias current is drawn from this pin through a switched
high-voltage current source. Internal current limit sense point
for drain current.

CONTROL (C) Pin:

Error amplifier and feedback current input pin for duty cycle
control. Internal shunt regulator connection to provide internal
bias current during normal operation. It is also used as the
connection point for the supply bypass and auto-restart/
compensation capacitor.

LINE-SENSE (L) Pin: (Y, R or F package only)

Input pin for OV, UV, line feed forward with DC
remote ON/OFF and synchronization. A connection to SOURCE
pin disables all functions on this pin.

EXTERNAL CURRENT LIMIT (X) Pin: (Y, R or F package
only)

Input pin for external current limit adjustment, remote
ON/OFF, and synchronization. A connection to SOURCE pin
disables all functions on this pin.

reduction,

MAX

FREQUENCY (F) Pin: (Y, R or F package only)

Input pin for selecting switching frequency: 132 kHz if
connected to SOURCE pin and 66 kHz if connected to
CONTROL pin. The switching frequency is internally set for
fixed 132 kHz operation in P and G packages.

SOURCE (S) Pin:

Output MOSFET source connection for high voltage power
return. Primary side control circuit common and reference point.

Figure 4. Y/R/F Pkg Line Sense and Externally Set Current Limit.

MULTI-FUNCTION (M) Pin:

This pin combines the functions of the LINE-SENSE (L) and
EXTERNAL CURRENT LIMIT (X) pins of the Y package
into one pin. Input pin for OV, UV, line feed forward with
DC

reduction, external current limit adjustment, remote

MAX

ON/OFF and synchronization. A connection to SOURCE pin
disables all functions on this pin and makes TOPSwitch-GX
operate in simple three terminal mode (like TOPSwitch-II).

Figure 3. Pin Configuration (top view).

4

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11/05

(P or G package only)

Figure 5. P/G Package Line Sense.

Figure 6. P/G Package Externally Set Current Limit.

TOPSwitch-GX Family Functional

PI-2633-011502

Duty Cycle (%)

IC (mA)

TOP242-5 1.6 2.0
TOP246-9 2.2 2.6
TOP250 2.4 2.7

5.2 6.0

5.8 6.6

6.5 7.3

I

CD1

I

B

Auto-restart

IL = 125 µA

IL < I

L(DC)

IL = 190 µA

78

10

38

Frequency (kHz)

IC (mA)

30

I

CD1

I

B

Auto-restart

132

Note: For P and G packages IL is replaced with IM.

IL < I

L(DC)

IL = 125 µA

Slope = PWM Gain

IL = 190 µA

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.

Th ree ter min als , FR EQU ENC Y, LIN E-S ENS E, a nd
EXTERNAL CURRENT LIMIT (available in Y, R or F
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:

TOP242-250

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. DC
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
variations 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 DC
mode, the value of the resistor determines the OV/UV thresholds
and the DC

above the under-voltage threshold. See Table 2 and Figure 11.

of 78% allows smaller input storage capacitor, lower

MAX

is reduced linearly starting from a line voltage

MAX

reduction. In this

MAX

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 MULTI­FUNCTION (M) pin. However, some of the functions become
mutually exclusive as shown in Table 3.

The FREQUENCY (F) pin in the Y, R or F 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.

11/05

O

5

TOP242-250

PI-2545-082299

S1 S2 S6 S7 S1 S2 S6 S7S0

S1 S7

S0

S0

5.8 V

4.8

V

S7

0 V

0 V

0 V

V

LINE

V

C

V

DRAIN

V

OUT

Note: S0 through S7 are the output states of the auto-restart counter

2

1

2

3

4

0 V

~

~

~

~

~

~

~

~

~

~

S6 S7

~

~

~

~

~

~

~

~

V

UV

~

~

~

~

~

~

~

~

S2

~

~

CONTROL (C) Pin Operation

The CONTROL pin is a low impedance node that is capable
of receiving a combined supply and feedback current. During
normal operation, a shunt regulator is used to separate the
feedback signal from the supply current. CONTROL pin voltage
VC is the supply voltage for the control circuitry including the
MOSFET gate driver. An external bypass capacitor closely
connected between the CONTROL and SOURCE pins is required
to supply the instantaneous gate drive current. The total amount
of capacitance connected to this pin also sets the auto-restart
timing as well as control loop compensation.

When rectified DC high voltage is applied to the DRAIN
pin during start-up, the MOSFET is initially off, and the
CONTROL pin capacitor is charged through a switched high
voltage current source connected internally between the DRAIN
and CONTROL pins. When the CONTROL pin voltage VC
reaches approximately 5.8 V, the control circuitry is activated
and the soft-start begins. The soft-start circuit gradually
increases the duty cycle of the MOSFET from zero to the
maximum value over approximately 10 ms. If no external
feedback/supply current is fed into the CONTROL pin by the
end of the soft-start, the high voltage current source is turned
off and the CONTROL pin will start discharging in response
to the supply current drawn by the control circuitry. If the
power supply is designed properly, and no fault condition
such as open loop or shorted output exists, the feedback loop
will close, providing external CONTROL pin current, before
the CONTROL pin voltage has had a chance to discharge to
the lower threshold voltage of approximately 4.8 V (internal
supply under-voltage lockout threshold). When the externally
fed current charges the CONTROL pin to the shunt regulator

voltage of 5.8 V, current in excess of the consumption of the
chip is shunted to SOURCE through resistor R

E

Figure 2. This current flowing through RE controls the duty cycle
of the power MOSFET to provide closed loop regulation. The
shunt regulator has a finite low output impedance ZC that sets
the gain of the error amplifier when used in a primary feedback
configuration. The dynamic impedance ZC of the CONTROL
pin together with the external CONTROL pin capacitance sets
the dominant pole for the control loop.

When a fault condition such as an open loop or shorted output
prevents the flow of an external current into the CONTROL
pin, the capacitor on the CONTROL pin discharges towards

4.8 V. At 4.8 V, auto-restart is activated which turns the output
MOSFET off and puts the control circuitry in a low current
standby mode. The high-voltage current source turns on and
charges the external capacitance again. A hysteretic internal
supply under-voltage comparator keeps V

within a window

C

of typically 4.8 V to 5.8 V by turning the high-voltage current
source on and off as shown in Figure 8. The auto-restart
circuit has a divide-by-eight counter which prevents the output
MOSFET from turning on again until eight discharge/charge
cycles have elapsed. This is accomplished by enabling the
output MOSFET only when the divide-by-eight counter reaches
full count (S7). The counter effectively limits TOPSwitch-GX
power dissipation by reducing the auto-restart duty cycle
to typically 4%. Auto-restart mode continues until output
voltage regulation is again achieved through closure of the
feedback loop.

Oscillator and Switching Frequency

The internal oscillator linearly charges and discharges an

as shown in

Figure 8. Typical Waveforms for (1) Power Up (2) Normal Operation (3) Auto-Restart (4) Power Down.

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11/05

6

internal capacitance between two voltage levels to create

PI-2550-092499

128 kHz

4 ms

Time

Switching

Frequency

V

DRAIN

136 kHz

a sawtooth waveform for the pulse width modulator. This
oscillator sets the pulse width modulator/current limit latch at
the beginning of each cycle.

The nominal switching frequency of 132 kHz was chosen to
minimize transformer size while keeping the fundamental EMI
frequency below 150 kHz. The FREQUENCY pin (available
only in Y, R or F package), when shorted to the CONTROL pin,
lowers the switching frequency to 66 kHz (half frequency) which
may be preferable in some cases such as noise sensitive video
applications or a high efficiency standby mode. Otherwise, the
FREQUENCY pin should be connected to the SOURCE pin
for the default 132 kHz.

TOP242-250

Figure 9. Switching Frequency Jitter (Idealized V

Waveforms).

DRAIN

To further reduce the EMI level, the switching frequency is
jittered (frequency modulated) by approximately ±4 kHz at
250 Hz (typical) rate as shown in Figure 9. Figure 46 shows
the typical improvement of EMI measurements with frequency
jitter.

Pulse Width Modulator and Maximum Duty Cycle

The pulse width modulator implements voltage mode control
by driving the output MOSFET with a duty cycle inversely
proportional to the current into the CONTROL pin

that
is in excess of the internal supply current of the chip (see
Figure 7). The excess current is the feedback error signal that
appears across RE (see Figure 2). This signal is filtered by an RC
network with a typical corner frequency of 7 kHz to reduce the
effect of switching noise in the chip supply current generated
by the MOSFET gate driver. The filtered error signal is
compared with the internal oscillator sawtooth waveform to
generate the duty cycle waveform. As the control current
increases, the duty cycle decreases. A clock signal from the
oscillator sets a latch which turns on the output MOSFET. The
pulse width modulator resets the latch, turning off the output
MOSFET. Note that a minimum current must be driven into
the CONTROL pin before the duty cycle begins to change.

The maximum duty cycle, DC

is set at a default maximum

MAX,

value of 78% (typical). However, by connecting the LINE­SENSE or MULTI-FUNCTION pin (depending on the
package) to the rectified DC high voltage bus through a
resistor with appropriate value, the maximum duty cycle can
be made to decrease from 78% to 38% (typical) as shown in
Figure 11 when input line voltage increases (see line feed
forward with DC

reduction).

MAX

Light Load Frequency Reduction

The pulse width modulator duty cycle reduces as the load at
the power supply output decreases. This reduction in duty
cycle is proportional to the current flowing into the CONTROL
pin. As the CONTROL pin current increases, the duty cycle
decreases linearly towards a duty cycle of 10%. Below 10%
duty cycle, to maintain high efficiency at light loads, the

frequency is also reduced linearly until a minimum frequency
is reached at a duty cycle of 0% (refer to Figure 7). The
minimum frequency is typically 30 kHz and 15 kHz for
132 kHz and 66 kHz operation, respectively.

This feature allows a power supply to operate at lower
frequency at light loads thus lowering the switching losses
while maintaining good cross regulation performance and low
output ripple.

Error Amplifier

The shunt regulator can also perform the function of an error
amplifier in primary side feedback applications. The shunt
regulator voltage is accurately derived from a temperature­compensated bandgap reference. The gain of the error
amplifier is set by the CONTROL pin dynamic impedance.
The CONTROL pin clamps external circuit signals to the V
voltage level. The CONTROL pin current in excess of the
supply current is separated by the shunt regulator and flows
through RE as a voltage error signal.

On-Chip Current Limit with External Programmability

The cycle-by-cycle peak drain current limit circuit uses the
output MOSFET ON-resistance as a sense resistor. A current
limit comparator compares the output MOSFET on-state drain
to source voltage, V
current causes V

DS(ON)

with a threshold voltage. High drain

DS(ON)

to exceed the threshold voltage and turns
the output MOSFET off until the start of the next clock cycle.
The current limit comparator threshold voltage is temperature
compensated to minimize the variation of the current limit due
to temperature related changes in R

of the output MOSFET.

DS(ON)

The default current limit of TOPSwitch-GX is preset internally.
However, with a resistor connected between EXTERNAL
CURRENT LIMIT (X) pin (Y, R or F package) or MULTI­FUNCTION (M) pin (P or G package) and SOURCE pin,
current limit can be programmed externally to a lower level
between 30% and 100% of the default current limit. Please
refer to the graphs in the typical performance characteristics
section for the selection of the resistor value. By setting current
limit low, a larger TOPSwitch-GX than necessary for the power

C

11/05

O

7

TOP242-250

PI-2637-060600

Oscillator

(SAW)

D

MAX

Enable from

X, L or M Pin (STOP)

Time

required can be used to take advantage of the lower R

DS(ON)

for
higher efficiency/smaller heat sinking requirements. With
a second resistor connected between the EXTERNAL
CURRENT LIMIT (X) pin (Y, R or F package) or MULTI­FUNCTION (M) pin (P or G package) and the rectified DC
high voltage bus, the current limit is reduced with increasing
line voltage, allowing a true power limiting operation against
line variation to be implemented. When using an RCD clamp,
this power limiting technique reduces maximum clamp
voltage at high line. This allows for higher reflected voltage
designs as well as reducing clamp dissipation.

The leading edge blanking circuit inhibits the current limit
comparator for a short time after the output MOSFET is turned
on. The leading edge blanking time has been set so that, if a
power supply is designed properly, current spikes caused by
primary-side capacitances and secondary-side rectifier reverse
recovery time should not cause premature termination of the
switching pulse.

The current limit is lower for a short period after the leading
edge blanking time as shown in Figure 52. This is due to
dynamic characteristics of the MOSFET. To avoid triggering
the current limit in normal operation, the drain current waveform
should stay within the envelope shown.

Line Under-Voltage Detection (UV)

At power up, UV keeps TOPSwitch-GX off until the input line
voltage reaches the under-voltage threshold. At power down,
UV prevents auto-restart attempts after the output goes out
of regulation. This eliminates power down glitches caused
by slow discharge of the large input storage capacitor present
in applications such as standby supplies. A single resistor
connected from the LINE-SENSE pin (Y, R or F package) or
MULTI-FUNCTION pin (P or G package) to the rectified DC

high voltage bus sets UV threshold during power up. Once the
power supply is successfully turned on, the UV threshold is
lowered to 40% of the initial UV threshold to allow extended
input voltage operating range (UV low threshold). If the UV
low threshold is reached during operation without the power
supply losing regulation, the device will turn off and stay off
until UV (high threshold) has been reached again. If the power
supply loses regulation before reaching the UV low threshold,
the device will enter auto-restart. At the end of each auto­restart cycle (S7), the UV comparator is enabled. If the UV
high threshold is not exceeded the MOSFET will be disabled
during the next cycle (see Figure 8). The UV feature can
be disabled independent of the OV feature as shown in
Figures 19 and 23.

Line Overvoltage Shutdown (OV)

The same resistor used for UV also sets an overvoltage threshold
which, once exceeded, will force TOPSwitch-GX output into
off-state. The ratio of OV and UV thresholds is preset at 4.5
as can be seen in Figure 11. When the MOSFET is off, the
rectified DC high voltage surge capability is increased to the
voltage rating of the MOSFET (700 V), due to the absence
of the reflected voltage and leakage spikes on the drain. A
small amount of hysteresis is provided on the OV threshold to
prevent noise triggering. The OV feature can be disabled
independent of the UV feature as shown in Figures 18 and 32.

Line Feed-Forward with DC

Reduction

MAX

The same resistor used for UV and OV also implements line
voltage feed-forward, which minimizes output line ripple and
reduces power supply output sensitivity to line transients.
This feed-forward operation is illustrated in Figure 7 by the
different values of IL (Y, R or F package) or IM (P or G package).
Note that for the same CONTROL pin current, higher line
voltage results in smaller operating duty cycle. As an added

Figure 10. Synchronization Timing Diagram.

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11/05

8

TOP242-250

feature, the maximum duty cycle DC

is also reduced

MAX

from 78% (typical) at a voltage slightly higher than the UV
threshold to 30% (typical) at the OV threshold (see Figure 11).
Limiting DC

at higher line voltages helps prevent transformer

MAX

saturation due to large load transients in TOP248, TOP249 and
TOP250 forward converter applications. DC

of 38% at

MAX

high line was chosen to ensure that the power capability of the
TOPSwitch-GX is not restricted by this feature under normal
operation.

Remote ON/OFF and Synchronization

TOPSwitch-GX can be turned on or off by controlling the
current into the LINE-SENSE pin or out from the EXTERNAL
CURRENT LIMIT pin (Y, R or F package) and into or out
from the MULTI-FUNCTION pin (P or G package) (see
Figure 11). In addition, the LINE-SENSE pin has a 1 V
threshold comparator connected at its input. This voltage
threshold can also be used to perform remote ON/OFF
control. This al lo ws easy implementation of remote
ON/OFF control of TOPSwitch-GX in several different ways.
A transistor or an optocoupler output connected between
the EXTERNAL CURRENT LIMIT or LINE-SENSE pins
(Y, R or F package) or the MULTI-FUNCTION pin (P or G
package) and the SOURCE pin implements this function with
“active-on” (Figures 22, 29 and 36) while a transistor or an
optocoupler output connected between the LINE-SENSE pin
(Y, R or F package) or the MULTI-FUNCTION (P or G package)
pin and the CONTROL pin implements the function with
“active-off” (Figures 23 and 37).

When a signal is received at the LINE-SENSE pin or the
EXTERNAL CURRENT LIMIT pin (Y, R or F package) or
the MULTI-FUNCTION pin (P or G package) to disable the
output through any of the pin functions such as OV, UV and
remote ON/OFF, TOPSwitch-GX always completes its current
switching cycle, as illustrated in Figure 10, before the output is
forced off. The internal oscillator is stopped slightly before the
end of the current cycle and stays there as long as the disable
signal exists. When the signal at the above pins changes state
from disable to enable, the internal oscillator starts the next
switching cycle. This approach allows the use of these pins
to synchronize TOPSwitch-GX to any external signal with a
frequency between its internal switching frequency and 20 kHz.

cycles between 4.8 V and 5.8 V (see CONTROL pin operation
section above) and runs entirely off the high voltage DC input,
but with very low power consumption (160 mW typical at
230 VAC with M or X pins open). When the TOPSwitch-GX
is remotely turned on after entering this mode, it will initiate
a normal start-up sequence with soft-start the next time the
CONTROL pin reaches 5.8 V. In the worst case, the delay from
remote on to start-up can be equal to the full discharge/charge
cycle time of the CONTROL pin, which is approximately
125 ms for a 47

µF CONTROL pin capacitor. This

reduced consumption remote off mode can eliminate
expensive and unreliable in-line mechanical switches. It also
allows for microprocessor controlled turn-on and turn-off
sequences that may be required in certain applications such as
inkjet and laser printers.

Soft-Start

Two on-chip soft-start functions are activated at start-up with a
duration of 10 ms (typical). Maximum duty cycle starts from
0% and linearly increases to the default maximum of 78% at
the end of the 10 ms duration and the current limit starts from
about 85% and linearly increases to 100% at the end of the
10 ms duration. In addition to start-up, soft-start is also
activated at each restart attempt during auto-restart and when
restarting after being in hysteretic regulation of CONTROL
pin voltage (V

), due to remote OFF or thermal shutdown

C

conditions. This effectively minimizes current and voltage
stresses on the output MOSFET, the clamp circuit and the
output rectifier during start-up. This feature also helps
minimize output overshoot and prevents saturation of the
transformer during start-up.

Shutdown/Auto-Restart

To minimize TOPSwitch-GX power dissipation under fault
conditions, the shutdown/auto-restart circuit turns the power
supply on and off at an auto-restart duty cycle of typically 4%
if an out of regulation condition persists. Loss of regulation
interrupts the external current into the CONTROL pin. V
regulation changes from shunt mode to the hysteretic auto­restart mode as described in CONTROL pin operation section.
When the fault condition is removed, the power supply output
becomes regulated, V

regulation returns to shunt mode, and

C

normal operation of the power supply resumes.

C

As seen above, the remote ON/OFF feature allows the
TOPSwitch-GX to be turned on and off instantly, on a cycle­by-cycle basis, with very little delay. However, remote
ON/OFF can also be used as a standby or power switch to
turn off the TOPSwitch-GX and keep it in a very low power
consumption state for indefinitely long periods. If the
TOPSwitch-GX is held in remote off state for long enough
time to allow the CONTROL pin to discharge to the internal
supply under-voltage threshold of 4.8 V (approximately 32 ms
for a 47

µF CONTROL pin capacitance), the CONTROL pin

goes into the hysteretic mode of regulation. In this mode, the
CONTROL pin goes through alternate charge and discharge

Hysteretic Over-Temperature Protection

Temperature protection is provided by a precision analog
circuit that turns the output MOSFET off when the junction
temperature exceeds the thermal shutdown temperature
(140 °C typical). When the junction temperature cools to
below the hysteretic temperature, normal operation resumes
providing automatic recovery. A large hysteresis of 70
(typical) is provided to prevent overheating of the PC board due
to a continuous fault condition. V

is regulated in hysteretic mode

C

and a 4.8 V to 5.8 V (typical) sawtooth waveform is present on
the CONTROL pin while in thermal shutdown.

11/05

°C

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9

TOP242-250

Bandgap Reference

All critical TOPSwitch-GX internal voltages are derived from
a temperature-compensated bandgap reference. This reference
is also used to generate a temperature-compensated current
reference, which is trimmed to accurately set the switching
frequency, MOSFET gate drive current, current limit, and the
line OV/UV thresholds. TOPSwitch-GX has improved circuitry
to maintain all of the above critical parameters within very tight
absolute and temperature tolerances.

High-Voltage Bias Current Source

This current source biases TOPSwitch-GX from the DRAIN
pin and charges the CONTROL pin external capacitance
during start-up or hysteretic operation. Hysteretic operation
occurs during auto-restart, remote OFF and over-temperature
shutdown. In this mode of operation, the current source
is switched on and off with an effective duty cycle of
approximately 35%. This duty cycle is determined by the
ratio of CONTROL pin charge (IC) and discharge currents
(I

CD1

and I

). This current source is turned off during normal

CD2

operation when the output MOSFET is switching. The effect of
the current source switching will be seen on the DRAIN voltage
waveform as small disturbances and is normal.

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 LINE­SENSE 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 DC

reduction with line voltage. In

MAX

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. 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 IOV (+225 µA
typical with 8 µA hysteresis). Between the UV and OV
thresholds, the output is enabled. For line feed-forward with

MAX

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

Overload Power Limiting

External Current Limit

Remote ON/OFF

*This table is only a partial list of many LINE-SENSE and EXTERNAL CURRENT LIMIT pin configurations that are possible.

Table 2. Typical LINE-SENSE and EXTERNAL CURRENT LIMIT Pin Configurations.

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11/05

10

▼

MAX

✓

✓ ✓ ✓ ✓ ✓

✓ ✓ ✓ ✓ ✓

)

✓ ✓ ✓ ✓

✓

✓ ✓ ✓ ✓ ✓ ✓

✓ ✓ ✓ ✓ ✓ ✓ ✓

TOP242-250

DC

reduction, the vertical axis represents the magnitude of

MAX

the DC
maximum duty cycle from 78% at I

. Line feed-forward with DC

MAX

reduction lowers

MAX

(+60 µA typical) to

L(DC)

38% at IOV (+225 µA).

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 to the 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 for remote ON/OFF.
Table 2 shows several possible combinations using this pin. See
Figure 11 for a description of the functions where the horizontal
axis (left hand side) represents the EXTERNAL CURRENT
LIMIT pin current. The meaning of the vertical axes varies
with function. For those that control the ON/OFF states of the
output such as remote ON/OFF, the vertical axis represents the
enable/disable states of the output. For external current limit,
the vertical axis represents the magnitude of the I

LIMIT

. Please
see graphs in the Typical Performance Characteristics section
for the current limit programming range and the selection of
appropriate resistor value.

MULTI-FUNCTION (M) Pin Operation (P and G
Packages)

The LINE-SENSE and EXTERNAL CURRENT LIMIT pin
functions are combined to a single MULTI-FUNCTION pin

for P and G packages. The comparator with a 1 V threshold
at the LINE-SENSE pin is removed in this case as shown in
Figure 2b. All of the other functions are kept intact. However,
since some of the functions require opposite polarity of input
current (MULTI-FUNCTION pin), they are mutually exclusive.
For example, line sensing features cannot be used simultaneously
with external current limit setting. When current is fed into
the MULTI-FUNCTION 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. When current is drawn out of the MULTI-FUNCTION
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 12b.

There are a total of five functions available through the use
of the MULTI-FUNCTION pin: OV, UV, line feed-forward
with DC

reduction, external current limit and remote

MAX

ON/OFF. A short circuit between the MULTI-FUNCTION
pin and SOURCE pin disables all five functions and forces
TOPSwitch-GX to operate in a simple three terminal mode
like TOPSwitch-II. The MULTI-FUNCTION 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
DC

reduction with line voltage. In this mode, the value

MAX

of the resistor determines the line OV/UV thresholds, and the
DC

is reduced linearly with increasing rectified DC high

MAX

voltage starting from just above the UV threshold. External
current limit programming is implemented by connecting the
MULTI-FUNCTION pin to the SOURCE pin through a resistor.
However, this function is not necessary in most applications
since the internal current limit of the P and G package devices
has been reduced, compared to the Y, R and F package
devices, to match the thermal dissipation capability of the P
and G packages. It is therefore recommended that the MULTI­FUNCTION pin is used for line sensing as described above and
not for external current limit reduction. The same pin can also

MULTI-FUNCTION PIN TABLE*

Figure Number 30 31 32 33 34 35 36 37 38 39 40

Three Terminal Operation

Under-Voltage

Overvoltage

Line Feed-Forward (DC

Overload Power Limiting

External Current Limit

Remote ON/OFF

*This table is only a partial list of many MULTI-FUNCTION pin configurations that are possible.

Table 3. Typcial MULTI-FUNCTION Pin Configurations.

▼

MAX

✓

✓ ✓ ✓

✓ ✓ ✓

)

✓ ✓

✓

✓ ✓ ✓ ✓

✓ ✓ ✓ ✓ ✓

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11/05

11

TOP242-250

-250 -200 -150 -100 -50 0 50 100 150 200 250 300 350 400

PI-2636-010802

Output

MOSFET

Switching

(Enabled)

(Disabled)

I

LIMIT

(Default)

DC

MAX

(78.5%)

Current

Limit

M Pin

L PinX Pin

Maximum

Duty Cycle

V

BG

-22 µA

-27 µA

V

BG

+ V

TP

I

I

I

I

I

UV

I

REM(N)

I

OV

Pin Voltage

Note: This figure provides idealized functional characteristics with typical performance values. Please refer to the parametric
table and typical performance characteristics sections of the data sheet for measured data.

X and L Pins (Y, R or F Package) and M Pin (P or G Package) Current (µA)

Disabled when supply
output goes out of
regulation

Figure 11. MULTI-FUNCTION (P or G package), LINSE-SENSE, and EXTERNAL CURRENT LIMIT (Y, R or F package) Pin Characteristics.

be used as a remote ON/OFF and a synchronization input in
both modes. Please refer to Table 3 for possible combinations
of the functions with example circuits shown in Figure 30
through Figure 40. A description of specific functions in terms
of the MULTI-FUNCTION pin I/V characteristic is shown in
Figure 11. The horizontal axis represents MULTI-FUNCTION
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) and OV triggers at IOV (+225 µA typical with
30 µA hysteresis). Between the UV and OV thresholds, the
output is enabled. For external current limit and line feed­forward with DC
magnitude of the I
DC

reduction lowers maximum duty cycle from 78% at I

MAX

(+60 µA typical) to 38% at IOV (+225 µA). External current

reduction, the vertical axis represents the

MAX

LIMIT

and DC

MAX

. Line feed-forward with

M(DC)

limit is available only with negative MULTI-FUNCTION
pin current. Please see graphs in the Typical Performance
Characteristics section for the current limit programming
range and the selection of appropriate resistor value.

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11/05

12

VBG + V

T

1 V

V

BG

240 µA

400 µA

CONTROL (C)

Y, R and F Package

(Voltage Sense)

(Positive Current Sense - Under-Voltage,

Overvoltage, ON/OFF Maximum Duty

Cycle Reduction)

(Negative Current Sense - ON/OFF,

Current Limit Adjustment)

PI-2634-022604

TOPSwitch-GX

LINE-SENSE (L)

EXTERNAL CURRENT LIMIT (X)

VBG + V

T

V

BG

240 µA

400 µA

CONTROL (C)

MULTI-FUNCTION (M)

(Positive Current Sense - Under-Voltage,

Overvoltage, Maximum Duty

Cycle Reduction)

(Negative Current Sense - ON/OFF,

Current Limit Adjustment)

PI-2548-022604

TOPSwitch-GX

P and G Package

Figure 12a. LINE-SENSE (L), and EXTERNAL CURRENT LIMIT (X) Pin Input Simplified Schematic.

TOP242-250

Figure 12b. MULTI-FUNCTION (M) Pin Input Simplified Schematic.

11/05

O

13

TOP242-250

PI-2654-071700

DC

Input

Voltage

+

-

D

S

C

CONTROL

F

PI-2655-071700

DC

Input

Voltage

+

-

D

S

C

CONTROL

F

PI-2656-040501

DC

Input

Voltage

+

-

D

S

C

STANDBY

QS can be an optocoupler output.

CONTROL

F

20

kΩ

R

HF

1 nF

Q

S

47 kΩ

Typical Uses of FREQUENCY (F) PIN

Figure 13. Full Frequency Operation (132 kHz). Figure 14. Half Frequency Operation (66 kHz).

14

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11/05

Figure 15. Half Frequency Standby Mode (For High Standby
Efficiency).

TOP242-250

X F

PI-2617-050100

DC

Input

Voltage

+

-

D

C S

D

S

C

CONTROL

L

C L X S F D

PI-2618-081403

DC

Input

Voltage

+

-

D

S

C

CONTROL

L

2 MΩR

LS

VUV = IUV x R

LS

V

OV = IOV x RLS

For RLS = 2 MΩ
V

UV

= 100 VDC

V

OV =

450 VDC

DC

MAX

@100 VDC = 78%

DC

MAX

@375 VDC = 38%

PI-2510-040501

DC

Input

Voltage

+

-

D M

S

C

VUV = RLS x I

UV

For Value Shown

VUV = 100 VDC

R

LS

6.2 V

2

MΩ

22

kΩ

CONTROL

PI-2620-040501

DC

Input

Voltage

+

-

D

S

C

CONTROL

L

2 MΩ

30 kΩ

R

LS

1N4148

V

OV

= I

OV x RLS

For Values Shown

VOV = 450 VDC

X

PI-2623-092303

DC

Input

Voltage

+

-

D

S

C

R

IL

For R

IL

= 12 kΩ

I

LIMIT

= 69%

See Figure 54b for
other resistor values
(R

IL

)

For

R

IL

= 25 kΩ

I

LIMIT

= 43%

CONTROL

X

PI-2624-040501

DC

Input

Voltage

+

-

D

S

C

2.5 MΩ

R

LS

6 kΩ

R

IL

100% @ 100 VDC
63% @ 300 VDC

I

LIMIT

=

I

LIMIT

=

CONTROL

Typical Uses of LINE-SENSE (L) and EXTERNAL CURRENT LIMIT (X) P ins

Figure 16. Three Terminal Operation (LINE-SENSE and
EXTERNAL CURRENT LIMIT Features Disabled.
FREQUENCY Pin Tied to SOURCE or CONTROL Pin).

Figure 18. Line-Sensing for Under-Voltage Only (Overvoltage

Disabled).

Figure 17. Line-Sensing for Under-Voltage, Overvoltage and Line
Feed-Forward.

Figure 19. Linse-Sensing for Overvoltage Only (Under-Voltage
Disabled). Maximum Duty Cycle Reduced at Low Line
and Further Reduction with Increasing Line Voltage.

Figure 20. Externally Set Current Limit.

Figure 21. Current Limit Reduction with Line Voltage.

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11/05

15

TOP242-250

X

PI-2625-040501

DC

Input

Voltage

+

-

D

S

C

ON/OFF

47 KΩ

QR can be an optocoupler
output or can be replaced by
a manual switch.

Q

R

CONTROL

PI-2621-040501

DC

Input

Voltage

+

-

D

S

C

CONTROL

L

47 kΩ

Q

R

R

MC

45 kΩ

QR can be an
optocoupler output or
can be replaced
by a manual switch.

ON/OFF

X

ON/OFF

47 kΩ

PI-2626-040501

DC

Input

Voltage

+

-

D

S

C

R

IL

Q

R

12 kΩ

For

R

IL

=

I

LIMIT

= 69%

25

kΩ

For

R

IL

=

I

LIMIT

= 43%

QR can be an optocoupler
output or can be replaced
by a manual switch.

CONTROL

PI-2627-040501

DC

Input

Voltage

+

-

D

S

C

CONTROL

L

47 kΩ

Q

R

R

MC

45 kΩ

QR can be an
optocoupler output
or can be replaced
by a manual switch.

ON/OFF

X

R

IL

PI-2622-040501

DC

Input

Voltage

+

-

D

S

C

CONTROL

L

47 kΩ

2

MΩ

Q

R

R

LS

ON/OFF

For RLS = 2 MΩ

V

UV

= 100 VDC

V

OV

= 450 VDC

QR can be an optocoupler
output or can be replaced
by a manual switch.

X

ON/OFF

47 kΩ

PI-2628-040501

DC

Input

Voltage

+

-

D

S

C

CONTROL

L

R

IL

R

LS

Q

R

2 MΩ

VUV = IUV x R

LS

V

OV = IOV x RLS

DC

MAX

@100 VDC = 78%

DC

MAX

@375 VDC = 38%

12 kΩ

For

R

IL

=

I

LIMIT

= 69%

QR can be an optocoupler
output or can be replaced
by a manual switch.

Typical Uses of LINE-SENSE (L) and EXTERNAL CURRENT LIMIT (X) Pins (cont.)

Figure 22. Active-on (Fail Safe) Remove ON/OFF. Figure 23. Active-off Remote ON/OFF. Maximum Duty Cycle

Reduced.

Figure 24. Active-on Remote ON/OFF with Externally Set Current
Limit.

Figure 26. Active-off Remote ON/OFF with LINE-SENSE. Figure 27. Active-on Remote ON/OFF with LINE-SENSE and

16

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11/05

Figure 25. Active-off Remote ON/OFF with Externally Set Current
Limit.

EXTERNAL CURRENT LIMIT.