NCP1607BDR2G ON Semiconductor, NCP1607BDR2G Datasheet - Page 13

• Manufacturer Part Number: NCP1607BDR2G
• Description: IC PFC CONTROLLER CRM 8SOIC
• Manufacturer: ON Semiconductor

Specifications of NCP1607BDR2G

• Mode: Critical Conduction (CRM)
• Current - Startup: 23.5µA
• Voltage - Supply: 9.5 V ~ 20 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Switching Frequency: 70 KHz
• Maximum Power Dissipation: 450 mW
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Frequency - Switching: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

out the bulk voltage ripple, then this on time is truly
constant over the ac line cycle.
when V
capacitor must be sized to ensure that the required on time
can be delivered at full power and the lowest input voltage
condition. The maximum on time is given by:
OFF TIME SEQUENCE
time in CRM operation varies with the instantaneous input
voltage. The NCP1607 determines the correct off time by
sensing the inductor voltage. When the inductor current
drops to zero, the drain voltage (“V
essentially floating and naturally begins to drop. If the
switch is turned on at this moment, then CRM operation
will be achieved. To measure this high voltage directly on
the inductor is generally not economical or practical.
Rather, a smaller winding is taken off of the boost inductor.
This winding, called the zero current detector (ZCD)
winding, gives a scaled version of the inductor output and
is more useful to the controller.
Note that the maximum on time of the controller occurs
Combining this equation with equation 1, gives:
where V
I
While the on time is constant across the ac cycle, the off
V
CHARGE
in
CONTROL
CTMAX
= 297 mA (max)
N
N
Ct w
ZCD
B
t
on(MAX)
R
= 2.9 V (min)
is at its maximum. Therefore, the Ct
ZCD
2 @ P
h @ Vac
+
OUT
R
Ct @ V
SENSE
@ L @ I
I
2
CHARGE
@ V
ZCD
CTMAX
CTMAX
CHARGE
drain
Figure 29. Implementation of the ZCD Winding
” in Figure 23) is
VCL(NEG)
VCL(POS)
Active
Clamp
Clamp
V
DD
http://onsemi.com
(eq. 5)
(eq. 6)
+
V
13
SDL
+
+
−
+
ZCD winding. When the drive is on, a negative voltage
appears on the ZCD winding. And when the drive is off, a
positive voltage appears. When the inductor current drops
to zero, then the ZCD voltage falls and starts to ring around
zero volts. The NCP1607 detects this falling edge and starts
the next driver on time. To ensure that a ZCD event has
truly occurred, the NCP1607’s logic (Figure 29) waits for
the ZCD pin voltage to rise above V
and then fall below V
CRM operation is easily achieved.
Figure 28 gives typical operating waveforms with the
V
V
V
V
V
V
Figure 28. Voltage Waveforms for Zero Current
CL(POS)
CL(NEG)
ZCDH
ZCDL
ZCD(off)
ZCD(on)
V
V
+
−
+
−
V
ZCDH
ZCDL
OUT
Shutdown
DRIVE
Winding
Drain
DRV
ZCD
ZCDL
Detection
(1.6 V typical). In this way,
Dominant
R
S
Latch
Reset
ZCDH
Q
Q
Demag
(2.1 V typical)