ncp1397a ON Semiconductor, ncp1397a Datasheet - Page 18

• Manufacturer Part Number: ncp1397a
• Description: High Performance Resonant Mode Controller With Integrated High-voltage Drivers
• Manufacturer: ON Semiconductor

Brown−Out protection
resonant converter from low DC input voltages. Below a
given level, the controller blocks the output pulses, above it,
it authorizes them. The internal circuitry, depicted by
Figure 40, offers a way to observe the high−voltage (HV)
rail. A resistive divider made of R
portion of the HV rail on Pin 5. Below the turn−on level, the
28 mA current source IBO is off. Therefore, the turn−on
level solely depends on the division ratio brought by the
resistive divider.
The Brown−Out circuitry (BO) offers a way to protect the
−4.00
−8.00
4.00
3.00
2.00
1.00
16.0
12.0
8.00
4.00
8.00
4.00
0
0
0
56.2 m
A − B
upper
Clock Pulses
Ct Voltage
and R
Figure 39. Typical Oscillator Waveforms
DT
65.9 m
lower
, brings a
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time in seconds
18
75.7 m
Figure 40. The Internal Brown−out Configuration
DT
DT
Rupper
Rlower
with an Offset Current Source
Vbulk
85.4 m
IBO
BO
V
DD
+
VBO
ON/OFF
+
−
95.1 m
BO