NCP1608BDR2G ON Semiconductor, NCP1608BDR2G Datasheet - Page 19

• Manufacturer Part Number: NCP1608BDR2G
• Description: IC PFC CTLR/PRECONVERTER 8-SOIC
• Manufacturer: ON Semiconductor

Specifications of NCP1608BDR2G

• Mode: Critical Conduction (CRM)
• Frequency - Switching: Adjustable
• Current - Startup: 24µA
• Voltage - Supply: 8.8 V ~ 12.5 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

Overvoltage Protection (OVP)
active PFC stages to react to changes in output load or input
voltages slowly. Consequently, there is a risk of overshoots
during startup, load steps, and line steps. For reliable
operation, it is critical that overvoltage protection (OVP)
prevents the output voltage from exceeding the ratings of
the PFC stage components. The NCP1608 detects
excessive output voltages and disables the driver until V
decreases to a safe level, which ensures that V
the PFC stage component ratings. An internal comparator
connected to the FB pin provides the OVP protection. The
OVP detection voltage is calculated using Equation 13:
V
Where V
Figure 43 depicts the operation of the OVP circuitry.
Undervoltage Protection (UVP)
is forced to equate to the peak of the line voltage. The
NCP1608 detects an undervoltage fault if V
low, such that V
the drive and error amplifier are disabled. The UVP feature
protects the system if there is a disconnection in the power
path to C
disconnected.
using Equation 17:
V
out(OVP)
out(UVP)
The low bandwidth of the feedback network causes
When the input voltage is applied to the PFC stage, V
The output voltage that causes an UVP fault is calculated
OVP
+
bulk
+ V
V
V
/V
OVP
REF
(i.e. C
UVP
REF
FB
@ V
@ R
is less than V
is the OVP detection threshold.
bulk
REF
out1
V
is unable to charge) or if R
out(OVPL)
@ R
@
R
R
out1
out2
out2
UVP
OVP Fault
V
V
out(OVPL)
+
@
) R
out(OVP)
@ R
R
. During an UVP fault,
R
DRV
V
out2
out2
FB
out
FB
V
V
) R
) 1
OVP
REF
@ R
out
FB
FB
@ V
out
is unusually
Figure 43. OVP Operation
) 1
REF
is within
(eq. 13)
(eq. 17)
http://onsemi.com
out1
* V
out
out
is
OVP(HYS)
19
inadvertently triggered by the 100 Hz or 120 Hz ripple of
V
Equation 14:
Where V
ripple and f
ensure that V
NCP1608 attempts to restart and to ensure noise immunity.
The output voltage at which the NCP1608 attempts a restart
(V
Open Feedback Loop Protection
against open feedback loop conditions by including OVP,
UVP, and FPP. Figure 44 illustrates three conditions in
which the feedback loop is open. The corresponding
number below describes each condition shown in
Figure 44.
out
The value of C
V
The OVP logic includes hysteresis (V
The NCP1608 features comprehensive protection
out(OVPL)
ripple(peak-peak)
. The minimum value of C
1. UVP Protection: The connection from R
2. OVP Protection: The connection from R
C
V
@ R
ripple(peak−peak)
bulk
the FB pin is open. R
to ground. The UVP comparator detects an UVP
fault and the drive and error amplifier are
disabled.
the FB pin is open. R
V
10 V and R
The OVP comparator detects an OVP fault and
the drive is disabled.
ripple(peak-peak)
out
w
out1
) is calculated using Equation 16:
line
. The ESD diode clamps the FB voltage to
out
2 @ p @ V
@
is the ac line frequency.
R
has sufficient time to discharge before the
R
out2
bulk
out2
is calculated using Equation 15:
out1
t 2 @ V
) R
ripple(peak−peak)
@ R
is sized to ensure that OVP is not
limits the current into the FB pin.
is the peak−to−peak output voltage
FB
FB
P
) 1
out2
out1
out(OVP)
out
pulls down the FB pin
pulls up the FB pin to
bulk
@ f
* V
is calculated using
line
@ V
out
OVP(HYS)
out
out1
out2
(eq. 16)
(eq. 14)
(eq. 15)
to
) to
to