參數(shù)資料
型號(hào): HA17384SRP
廠商: Hitachi,Ltd.
元件分類: 基準(zhǔn)電壓源/電流源
英文描述: High Speed Current Mode PWM Control IC for Switching Power Supply
中文描述: 高速開關(guān)電源電流模式PWM控制IC
文件頁數(shù): 28/31頁
文件大小: 145K
代理商: HA17384SRP
HA17384SPS/SRP, HA17384HPS/HRP, HA17385HPS/HRP
28
Notice for Use
1. OVP Latch Block
Case
When DC power is applied directly as the power supply of the HA17384H, HA17385H, without using
the transformer backup coil. Also, when high-frequency noise is superimposed on the V
IN
pin.
Problem
The IC may not be turn on in the case of a circuit in which V
IN
rises quickly (10 V/100
μ
s or faster),
such as that shown in figure 16. Also, the OVP latch may operate even though the FB pin is normally at
V
OVP
or below after the IC is activated.
Reason
Because of the IC circuit configuration, the timer latch block operates first.
Remedy (counter measure)
Take remedial action such as configuring a time constant circuit (R
B
, C
B
) as shown in figure 17, to keep
the V
IN
rise speed below 10 V/100
μ
s. Also, if there is marked high-frequency noise on the V
IN
pin, a
noise cancellation capacitor (C
N
) with the best possible high-frequency characteristics (such as a
ceramic capacitor) should be inserted between the V
IN
pin and GND, and close to the V
IN
pin.
When configuring an IC power supply with an activation resistance and backup winding, such as an
AC/DC converter, the rise of V
IN
will normally be around 1 V/100
μ
s, and there is no risk of this problem
occurring, but careful attention must be paid to high-frequency noise.
Also, this phenomenon is not occuring to the HA17384S, because OVP function is not built-in.
Output
Input
V
IN
V
IN
GND
Feedback
HA17384
Series
Figure 16 Example of Circuit with Fast V
IN
Rise Time
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