TOP252 データシートの表示（PDF） - Power Integrations, Inc

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TOP252

AC/DC Converters Off-Line Switcher IC 26W/64W PK

Power Integrations, Inc 

TOP252-262

+

DC

Input

Voltage

RIL

For RIL = 12 kΩ

ILIMIT = 61%

For RIL = 19 kΩ

ILIMIT = 37%

See Figure 55b for other

resistor values (RIL) to

select different ILIMIT values.

D

M

CONTROL

C

-

S

Figure 8. P/G Package Externally Set Current Limit.

PI-4713-021308

Auto-Restart

78

Slope = PWM Gain

(constant over load range)

CONTROL

Current

100

reduction, output overvoltage protection (OVP), external current

limit adjustment, remote ON/OFF and device reset. A

connection to SOURCE pin disables all functions on this pin

and makes TOPSwitch-HX operate in simple three terminal

mode (like TOPSwitch-II).

FREQUENCY (F) Pin (TOP254-258Y, and all E and L packages):

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 66 kHz

operation in the P, G, M package and TOP259YN, TOP260YN

and TOP261YN.

SIGNAL GROUND (G) Pin (TOP259YN, TOP260YN &

TOP261YN only):

Return for C pin capacitor and X pin resistor.

SOURCE (S) Pin:

Output MOSFET source connection for high voltage power

return. Primary side control circuit common and reference point.

TOPSwitch-HX Family Functional Description

55

25

Full Frequency Mode

CONTROL

Current

132

Low

Variable

Frequency

Frequency

Mode

66

Mode

Jitter

Multi-Cycle

Modulation

30

ICD1 IB

IC01

IC02

IC03

ICOFF

CONTROL

Current

PI-4645-041107

Figure 9. Control Pin Characteristics (Multi-Mode Operation).

Like TOPSwitch-GX, TOPSwitch-HX 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 9.

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 and thermal

shutdown, the TOPSwitch-HX 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, VOLTAGE-MONITOR, and

EXTERNAL CURRENT LIMIT (available in Y and E/L packages),

two terminals, VOLTAGE-MONITOR and EXTERNAL CURRENT

LIMIT (available in M package) or one terminal MULTI-FUNCTION

(available in P and G package) have been used to implement

some of the new functions. These terminals can be connected

to the SOURCE pin to operate the TOPSwitch-HX in a

TOPSwitch-like three terminal mode. However, even in this three

terminal mode, the TOPSwitch-HX offers many transparent

features that do not require any external components:

1. A fully integrated 17 ms soft-start significantly reduces or

eliminates output overshoot in most applications by sweeping

both current limit and frequency from low to high to limit the

peak currents and voltages during start-up.

2. A maximum duty cycle (DCMAX) of 78% allows smaller input

storage capacitor, lower input voltage requirement and/or

higher power capability.

3. Multi-mode operation optimizes and improves the power

supply efficiency over the entire load range while maintaining

good cross regulation in multi-output supplies.

www.powerint.com

7

Rev. H 06/13

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