TOP266(2010) Ver la hoja de datos (PDF) - Power Integrations, Inc

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TOP266
(Rev.:2010)

Integrated Off-Line Switcher with EcoSmart® Technology for Highly Effcient Power Supplies

Power Integrations, Inc 

TOP264-271

+

DC

Input

Voltage

-

VUV = IUV × RLS + VV (IV = IUV)

VOV = IOV × RLS + VV (IV = IOV)

RLS

4 MΩ For RLS = 4 MΩ

VUV = 102.8 VDC

VOV = 451 VDC

DCMAX@100 VDC = 76%

D

V

DCMAX@375 VDC = 41%

CONTROL

C

S

X

For RIL = 12 kΩ

ILIMIT = 61%

RIL

12 kΩ

See Figure 35 for

other resistor values

(RIL) to select different

ILIMIT values.

Figure 4. Package Line Sense and Externally Set Current Limit.

Auto-Restart

78

Slope = PWM Gain

CONTROL

Current

100

TOP264-271 Functional Description

Like TOPSwitch-HX, TOP264-271 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 5.

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 shut-

down, the TOP264-271 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 have been used to implement

some of the new functions. These terminals can be connected

to the SOURCE pin to operate the TOP264-271 in a TOPSwitch-

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

mode, the TOP264-271 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.

4. Switching frequency of 132 kHz reduces the transformer size

with no noticeable impact on EMI.

5. Frequency jittering reduces EMI in the full frequency mode at

high load condition.

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-5665-110609

Figure 5. Control Pin Characteristics (Multi-Mode Operation).

6. Hysteretic over-temperature shutdown ensures thermal fault

protection.

7. Packages with omitted pins and lead forming provide large

drain creepage distance.

8. Reduction of the auto-restart duty cycle and frequency to

improve the protection of the power supply and load during

open loop fault, short circuit, or loss of regulation.

9. Tighter tolerances on I2f power coefficient, current limit

reduction, PWM gain and thermal shutdown threshold.

The VOLTAGE-MONITOR (V) pin is usually used for line sensing

by connecting a 4 MW resistor from this pin to the rectified DC

high voltage bus to implement line overvoltage (OV), under-

voltage (UV) and dual-slope line feed-forward with DCMAX

reduction. In this mode, the value of the resistor determines the

OV/UV thresholds and the DCMAX is reduced linearly with a dual

slope to improve line ripple rejection. In addition, it also

provides another threshold to implement the latched and

4

Rev. B 03/10

www.powerint.com

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