HA16138PS Datasheet, PDF (6/20 Pages) Hitachi Semiconductor – AC/DC Switching Converter Controller IC With High-Voltage Power MOS FET

HA16138PS
Functional Description
Note: Unless specified otherwise, characteristic values in the text and figures are typical values or design
values.
Starter Circuit
When power is turned on, the starter circuit operates during standby mode, and a constant current is
supplied from the drain pins to the VDD pin. This constant current supplies the external capacitance
charge current for charging up the VDD pin and the standby current consumed by the IC itself while on
standby.
Therefore, the start-up bleeder resistance required by previous products with no on-chip starter circuit is no
longer necessary. The starter circuit detects both the drain voltage and the VDD pin voltage, and controls
VDD so that the IC does not start up if the drain voltage is less than 75 V.
Vb+
DRAIN
0
75V
0
Istart
VDD
0
11V
8V
0
CT
0
COMP
0
DC
OUTPUT 0
Figure 1 Start-Up Timing
UVL Circuit
The UVL circuit is a function that monitors the VDD voltage, and stops IC operation if VDD is low. The
VDD detection voltage has a hysteresis characteristic; the operating start VDD voltage is 11 V, and the
operation stop voltage, 8 V.
In standby mode at the operation stop voltage or below, the UVL circuit keeps the power MOS FET turned
off, and performs control of soft start circuit resetting, internal reference voltage circuit stoppage, and so
forth.
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