AP1694AS-13 Просмотр технического описания (PDF) - Diodes Incorporated.

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AP1694AS-13

OFFLINE, HIGH PF, HIGH EFFICIENCY DIMMABLE LED DRIVER CONTROLLER

Diodes Incorporated. 

Application Information Based on Buck Structure (cont.)

Fault Protection

Over Voltage Protection and Output Open Protection

VCC

RFB1

RFB2

FB

AP1694A

AP1694AS-13

Figure 4. OVP Circuit

The output voltage is sensed by the auxiliary winding voltage of the Buck transformer. The VCC pin and FB pin provide over voltage protection

function. When the output is open or large transient happens, the output voltage will exceed the rated value. When the voltage of Vcc cap exceeds

VCC_OVP or VFB_CV, the over voltage is triggered and the IC will discharge VCC. When the VCC is below the UVLO threshold voltage, IC will start a

new work cycle and the Vcc cap is charged again by start resistance. If the over voltage condition still exists, the system will work in hiccup mode.

Attention: If the external fast startup circuit is adding in the application and the over voltage protection and output open protection happen, the IC

will trigger latch.

Output Short Protection

When the output is shorted, the output voltage will be clamped at zero. At this condition, VCC will drop down without auxiliary winding for power

supply, and the VCC will drop to UVLO threshold voltage. The IC will shut down and restart a new operating cycle, and the VCC is charged by

startup resistance. When VCC is higher than Vcc_start voltage, IC will output a bunch of pulses to control power switch on and off. When still no FB

signal detected, the device will not output more pulses. The VCC will again drop to VCC UVLO threshold. If output short condition still exists, the

system will operate in hiccup mode.

Attention: If the external fast startup circuit is adding in the application, the device will not work at UVLO mode, and the device will work at

minimum toff mode.

Over Temperature Protection

AP1694AS-13 has two kinds of over-temperature protection processes. First, if the system is operating normally, the ambient temperature is

changed to +170°C, and suddenly the IC will trigger over-temperature protection which leads to a latch work mode. Second, if the system starts

when the ambient temperature is higher than +150°C, over temperature protection will be triggered. So, the AP1694AS-13 can startup

successfully when the ambient temperature is less than +150°C.

Components Selection Guide

If the system’s spec is changed, please refer to the design sheet of the AP1694AS-13 and select the compatible system parameter. When the

system needs to be adjusted slightly, please refer to the table below and adjust the value of the related component.

Item

IO

Output Current Ripple

ton_initial

Output Open Voltage

Dimming Performance

EMI

Line Compensation

Description

Output current

Small current ripple is good for LED life

System initial on time, used to startup the system

Setting the output voltage when the LED is open

Improve the dimming performance

Pass EN 55022 class B with 6DB margin

To get a good line regulation

Related Components

R8

C4

R1

R5, R6

R1, RF, R9, C2, C4

L1, C1

R7

AP1694AS-13

Document number: DS37789 Rev. 1 - 2

11 of 14

www.diodes.com

July 2015

© Diodes Incorporated

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