NCP1396B ON Semiconductor, NCP1396B Datasheet - Page 14

• Manufacturer Part Number: NCP1396B
• Description: High Performance Resonant Mode Controller featuring High-voltage Drivers
• Manufacturer: ON Semiconductor

1. The startup thresholds are different, the A starts
2. The A version does not activate the soft-start
to pulse for Vcc = 13.3 V whereas the B pulses
for Vcc = 10.5 V. The turn off levels are the
same however. The A is recommended for
consumer products where the designer can use an
external startup resistor, whereas the B is more
recommended
applications where a 12 V auxiliary supply
directly powers the chip.
upon release of the fast fault input. This is to let
the designer implement skip cycle. To the
opposite, the B version goes back to operation
Vcc
FMAX sets
the maximum Fsw
Rt sets
Fmin for VFB = 0
RDT sets
the dead-time
for
Fmax
Rt
DT
FB
industrial
Rfb
20k
vref
vref
Figure 31. The simplified VCO architecture
/
vdd
vdd
vdd
NCP1396A, NCP1396B
Imin
Imin
Cint
medical
http://onsemi.com
IDT
0 to I_Fmax
14
FBinternal
Voltage-Controlled Oscillator
allowing operation from 100 kHz up to 1 MHz. However,
as a division by two internally creates the two Q and Qbar
outputs, the final effective signal on output Mlower and
Mupper switches between 50 kHz and 500 kHz. The VCO
is configured in such a way that if the feedback pin goes
up, the switching frequency also goes up. Figure 31
shows the architecture of this oscillator.
+
-
max
max
Fsw
upon the fast fault pin release via a soft-start
sequence.
The VCO section features a high-speed circuitry
Vb_off
D
Clk
S
R
Q
Q
Vfb < Vb_off ?
Start fault timer
A
B