NCP1605FORWGEVB ON Semiconductor, NCP1605FORWGEVB Datasheet - Page 22

• Manufacturer Part Number: NCP1605FORWGEVB
• Description: EVAL BOARD FOR NCP1605FORWG
• Manufacturer: ON Semiconductor

Specifications of NCP1605FORWGEVB

• Design Resources: NCP1605FORWGEVB BOM NCP1605FORWGEVB Gerber Files NCP1605 EVB Schematic
• Main Purpose: AC/DC, Primary and Secondary Side with PFC
• Outputs And Type: 1, Isolated
• Voltage - Output: 19V
• Current - Output: 8A
• Voltage - Input: 90 ~ 265VAC
• Regulator Topology: Forward Converter
• Frequency - Switching: 133kHz
• Board Type: Fully Populated
• Utilized Ic / Part: NCP1217, NCP1605
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: NCP1605FORWG
• Other names: NCP1605FORWGEVBOS

The propagation delay (V
output high) is in the range of 300 ns, typically.
The Zero Current Detection:
•
•
Remarks:
•
Is used to detect the dead−time sequences (“DT” high)
and hence, to process (V
output (V
the on−time modulation block.
Prevents the MOSFET from turning on as long as the
“DT” and “ZCD” signals are low. This is the case as
long as some current flows through the coil. This
delaying action on the output stage tends to make the
MOSFET turn on at the valley. To further optimize the
valley switching, one can apply the voltage of an
auxiliary winding to Pin 6 (CS
compared to an internal 100 mV reference, so that
ZCD turns high only if (V
A resistor can be placed between Pin 6 and ground to
increase the ZCD precision.
Filter
EMI
R
sense
CONTROL
R
V
ocp
in
C
). In other words, this is an input of
CS
in
5
in
Pin6
The CS block performs the overcurrent protection and the zero current detection.
TON
Pin6
V
(I COIL )zcd +
lower than 100 mV) to (drive
Icoil
dd
) from the error amplifier
< 100 mV).
OUT
Current Mirror
). The voltage is
Ics
V
dd
R pin6 @ R CS
Figure 60. Current Sense Block
I
Ics
cs
R OCP
> 250 mA ≥ OCP
6
Icoil
100 mV
http://onsemi.com
CS
Rzcd
out
Rdrv
(RESET of the PWM latch)
+
-
100 mV +
22
•
•
It is recommended to:
OCP
outON
Vzcd
It is worth highlighting that the circuit permanently
senses the coil current and that it prevents any turn on
of the power switch as long as the core is not reset.
This feature protects the MOSFET from the possible
excessive stress it could suffer from, if it was allowed
to turn on while a huge current flows through the coil.
In particular, this scheme effectively protects the PFC
stage during the startup phase when huge in−rush
currents charge the output capacitor.
In addition this detection method does not require any
auxiliary winding. A simple coil can then be used in
the PFC stage.
ZCD
R pin6 @ 250 mA
1. Keep R
2. Choose R
than (3 x R
leakage prevents a proper zero current detection.
For instance, if R
exceed 6.6 kW.
100 mV
S
LdT
R
output
OCP
buffer
Q
ZCD
OCP
equal to or lower than 5 kW
@ (I COIL ) MAX +
as high as possible but not bigger
Vcc
). This is to avoid that the Pin 6
OCP
DT
DRV
is 2.2 kW, R
10
400 W
R pin6
L1
M1
ZCD
C
@ (I COIL ) MAX
D1
bulk
should not
Vout
LOAD