AP1685MTR-G1 查看數據表（PDF） - Diodes Incorporated.
零件编号
产品描述 (功能)
比赛名单
AP1685MTR-G1 Datasheet PDF : 14 Pages
| |||
A Product Line of
Diodes Incorporated
AP1685
Application Information (Cont.)
According to Figure 2, when the falling edge of 0.1V is sensed by the FB pin, the AP1685 will see the tOFF time is over and delay 1µs to start a
new operating cycle. In this way we can realize valley on function.
Fault Protection
Over Voltage Protection and Output Open Protection
VCC
RFB1
RFB2
FB
AP1685
Figure 3. 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, the 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.
Output Short Protection
When the output is shorted, the output voltage will be clamped at 0. 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 the VCC is higher than Vcc_start voltage, the IC will output a bunch of pulse to control power MOSFET on and off, which will
consume the energy stored in the VCC cap, because of no VCC supply from the auxiliary winding, the VCC will drop down to VCC UVLO threshold
voltage again. If output short condition still exists, the system will operate in hiccup mode.
Over Temperature Protection
The AP1685 has two kinds of over temperature protection processes. First, the system is operating normally, the ambient temperature is changed
to +170°C suddenly, the IC will trigger over temperature protection which leads to a latch work mode. Second, if the system starts, the over
temperature protection will be triggered when the ambient temperature is higher than +150°C. So the AP1685 can startup successfully when the
ambient temperature is less than +150°C.
Recommended Applications
The AP1685 is a device which internally integrates a MOSFET, the output current is limited by the internal integrated MOSFET, using this device
can cover up to 10W’s application meanwhile the output current is less than 200mA.
Components Selection Guide
If the system’s output spec is changed, please refer to the design sheet of the AP1685 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
Line Compensation
Startup Time
EMI
Description
LED current
Small current ripple is good for LED life
System initial on time, used to start up the system
Setting the output voltage when the LED is open
To get a good line regulation
System startup time
Pass EN 55022 class B with 6DB margin
Related Components
R8
C4
R1
R5, R6
R7, R9
R2, C3, T1
L1, C1, C2
AP1685
Document number: DS37311 Rev. 1 - 2
10 of 14
www.diodes.com
September 2014
© Diodes Incorporated
Share Link: 