LNK6664ESLASHKSLASHV datasheet(5/24 Pages) POWERINT

5 / 24 page

Rev. E 06/15

LinkSwitch-HP

www.power.com

Remote On/Off and Fast AC Reset

The PROGRAM pin can be used to turn on/off the device

remotely. If the voltage on the pin is set to 1.35 V externally, the

device stops switching. After releasing the PROGRAM pin the

PROGRAM pin device commences switching when the voltage

drops below 0.535 V.

The PROGRAM pin can also be used to reset the device latch

after a latching OVP or OTP event. If the voltage on the pin is

set to 3.4 V externally, the device latch is reset. Once the

voltage drops below 0.535 V, device will start switching.

High-Voltage Bus Sensing

LinkSwitch-HP senses indirectly the HV voltage bus V

BUS during

the power MOSFET on-time by monitoring the current flowing

out of the FEEDBACK pin. During the MOSFET on-time the

voltage across the auxiliary winding is proportional to the voltage

across the input winding. The current flowing through resistor

FB1 (see Figure 8) is therefore representing VBUS. Indirect line

sensing minimizes power dissipation and is used for line UV or

line OV protection and current limit compensation over line.

At power-up the current out of the FEEDBACK pin has to

exceed the line undervoltage turn-on threshold (brown-in)

current I

FB(UVREF) = -250 mA (typ.) before switching is enabled.

During normal operation switching is disabled if the FEEDBACK

pin current falls below the line undervoltage turn-off threshold

(brown-out) current I

FB(UVOFF) = -100 mA (typ.) for at least 8

consecutive switching cycles. After switching has ended, the

device enters auto-restart. The applicable auto-restart off-

period t

AR(OFF)1 = 150 ms (typ.).

Switching is also stopped if the FEEDBACK pin current exceeds

the line overvoltage threshold current I

FB(OV) = -1.15 mA (typ.) for

at least 2 consecutive switching cycles.

Current Limit Compensation Over Line

The high-voltage bus is sensed by means of measuring the

current out of the FEEDBACK pin during the MOSFET on-time.

To limit available overload power over line the set current limit is

compensated as shown in Figure 7. The compensation is

disabled at peak currents below 50% of the set current limit,

and is re-enabled at 62.5% of the set current limit.

Soft-Start

A digital soft-start is implemented to reduce component stress

at power supply start-up. The internal reference voltage will ramp

up to 2 V during t

SOFT (typ. 15 ms) at start-up. The loop will

typically close (output reaches regulation) during this time to

ensure smooth output voltage rise.

Fault Filter

This is the digital filter to handle all the fault conditions including

line overvoltage, line undervoltage, output overvoltage, and

output undervoltage, thermal shutdown as well as package

level fault (pin open-circuit or pin-to-pin short-circuit).

Transconductance Amplifier

The controller uses a high gain (typ. 70 dB) transconductance

amplifier to ensure exceptional output regulation.

Figure 7.

Current Limit Compensation Over Line.

Figure 8.

Indirect High-Voltage Bus Sensing.

Figure 6.

Optional Shutdown Time Extension Programming.

100

150

200

250

300

350

400

450

500

110

100

PROGRAM Pin Capacitor Value (nF)

124 k

Ω

PROGRAM Pin Resistor Value

78.7 k

Ω

52.3 k

Ω

34.8 k

Ω

23.2 k

Ω

10.0 k

Ω

15.0 k

Ω

VAUX

RFB1

VFB

VBUS

VSEC

RFB2

PI-6837-120312

CONTROL

-150

-300

-450

-600

-750

-1050 -1200

-900

FEEDBACK Pin Current During MOSFET On-Time

110

100

LNK6664E/K/V Datasheet(PDF) 5 Page - Power Integrations, Inc.

LNK6664E/K/V Datasheet(HTML) 5 Page - Power Integrations, Inc.

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