TOP264VG datasheet(4/40 Pages) POWERINT

4 / 40 page

Rev. F 05/15

TOP264-271

www.power.com

PI-5665-110609

CONTROL

Current

CONTROL

Current

CONTROL

Current

ICOFF

IC03

IC02

IC01

ICD1

100

132

Slope = PWM Gain

Auto-Restart

Variable

Frequency

Mode

Low

Frequency

Mode

Multi-Cycle

Modulation

Jitter

Full Frequency Mode

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 6.

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 (DC

MAX) 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.

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 M

W 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 DC

MAX

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

OV/UV thresholds and the DC

MAX is reduced linearly with a dual

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

provides another threshold to implement the latched and

Figure 6.

Control Pin Characteristics (Multi-Mode Operation).

Input

Voltage

CONTROL

RIL

RLS

12 k

Ω

4 M

Ω

VUV = IUV × RLS + VV (IV = IUV)

VOV = IOV × RLS + VV (IV = IOV)

For RLS = 4 MΩ

DCMAX@100 VDC = 76%

DCMAX@375 VDC = 41%

For RIL = 12 kΩ

ILIMIT = 61%

See Figure 37 for

other resistor values

(RIL) to select different

ILIMIT values.

UV = 102.8 VDC

OV = 451 VDC

Figure 5.

Package Line-Sense and Externally Set Current Limit.

TOP264VG 数据表(PDF) 4 Page - Power Integrations, Inc.

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