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零件编号 | MS1003SH | ||
描述 | Control IC | ||
制造商 | SHINDENGEN | ||
LOGO | |||
1 Page
MS1003SH・MS1004SH
Application Note Ver.2.2
The product and product specifications are subject to change without notice.
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SHINDENGEN ELECTRIC MFG. CO. , LTD
MS1003SH・MS1004SH
Application Note Ver.2.2
3.1.2 Soft start
At startup, the OCL level changes in four stages. Current flowing to the main switch also increases in stages.
The envelope curves of the current to the main switch are shaped in four steps to avoid abrupt switch
startups.
The soft start time depends on the Tss1 to Tss3 settings. The time settings are determined by the IC.
Normal OCL level
Steady-state
operation
3.1.3 Bias assist
Soon after oscillation begins during startup, the voltage drops, and the oscillation may halt. To prevent this
and ensure proper startup, the bias assist function supplies energy to the Vcc pin.
Shown below is a schematic diagram of Vcc startup incorporating the bias assist function.
Assist function
activates.
If the voltage drops below the oscillation
stop voltage, oscillation halts, and the
startup circuit must restart.
The voltage remains above the oscillation
stop voltage to ensure that oscillation
does not halt.
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SHINDENGEN ELECTRIC MFG. CO. , LTD
Output current Io
Overload beyond the droop setting
MS1003SH・MS1004SH
Application Note Ver.2.2
Main SW device
current ID
Control voltage
Vcc
Feedback voltage
VF/B
The bias assist function turns off after the IC is latched.
3.4.4 VCC-GND short circuit protection
If Vcc and GND short-circuit, current flows continuously to the startup circuit, and heat builds up in the IC.
A function reduces Icc in the event of short circuits to prevent excessive heat buildup.
3.4.5 Leading edge blank (LEB)
The MS1003SH and MS1004SH incorporate a leading edge blank function, which rejects trigger signals
from the drain current detection circuit for a certain period of time after the main switching device is turned
on to improve the noise margin.
This function prevents false detection due to a gate drive current generated the moment the main switching
device is turned on or to a current discharged from the resonating capacitor.
3.4.6 On-trigger malfunction prevention circuit
At startup or in the event of a load short circuit, the output
voltage drops to levels significantly below the set voltage.
Since the control coil voltage is proportional to the output
voltage, it drops significantly as well. In this case, a false
on-trigger timing may be detected due to the ringing voltage
while the device is off. The device may switch before the
current critical point.
The on-trigger is disabled
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約Ap0p.r2o5xV.
Ttoonnddeeaadd
0.25 V
VZ/C
ID
To address this problem, the MS1003SH and MS1004SH
incorporate a circuit for preventing on-trigger malfunctions at
startup or in the event of short circuits.
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This function disables the on-trigger during the period Tondead after the main switching device in the IC is
turned off. This prevents false detection due to the ringing voltage while the device is off.
3.4.7 TSD
The MS1003SH and MS1004SH incorporate a thermal shutdown circuit. The IC is latched at 150°C (TYP),
and oscillation is stopped. The IC is unlatched by momentarily dropping the VCC pin voltage to the VUL
(unlatch voltage) or below.
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SHINDENGEN ELECTRIC MFG. CO. , LTD
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页数 | 30 页 | ||
下载 | [ MS1003SH.PDF 数据手册 ] |
零件编号 | 描述 | 制造商 |
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