NCP1910GEVB ON Semiconductor, NCP1910GEVB Datasheet - Page 24

• Manufacturer Part Number: NCP1910GEVB
• Description: BOARD EVAL NCP1910DEMO-B-TLS
• Manufacturer: ON Semiconductor
• Series: -r

Specifications of NCP1910GEVB

• Design Resources: NCP1910 Schematic NCP1910GEVB BOM
• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Power - Output: -
• Voltage - Output: Adj down to 0.8V
• Current - Output: 3A
• Voltage - Input: 3 ~ 5.5 V
• Regulator Topology: Buck
• Frequency - Switching: 1MHz
• Board Type: Fully Populated
• Utilized Ic / Part: NCP1910
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: NCP1910GEVBOS

PFC Current Sense
sense scheme in Figure 47. The device maintains the voltage
at CS pin to be zero voltage, i.e. V
Where:
of components for current sensing. The sense current I
represents the inductor current I
duty modulation to generate the multiplier voltage V
Over−Power Limitation
Protection. Equation 13 would insist in the fact that it
provides the flexibility in the R
allows to detect in−rush currents.
PFC Over−Current Protection (OCP)
larger than I
the CS pin is typical 10 mV and it is neglected in the
calculation. Hence, the maximum OCP inductor current
threshold I
PFC drive goes low. The device automatically resumes
operation when the inductor current goes below the
threshold.
The device senses the inductor current I
This scheme has the advantage of the minimum number
PFC Over−Current Protection is reached when I
When over−current protection threshold is reached, the
♦
♦
♦
♦
Figure 47. PFC Current Sensing Configuration
detection.
R
V
V
R
R
R
SENSE
ac,on
ac,off
SENSE
CS
SENSE
R
I
L OCP
CS
is the offset resistor between CS pin and
L(OCP)
is the rms ac voltage to starts PFC operating.
S(OCP)
the rms ac voltage for line brown−out
.
is the sense resistor to sense I
I
I
+
L
CS
I
L
is obtained in Equation 14.
R
(200 mA typical). The offset voltage of
CS
R
CS
I
SENSE
CS
I
V
S OCP
+
CS
−
+
NCP1910
R
(OPL),
SENSE
R
+
L
CS
GND
R
and will be used in the PFC
SENSE
R
SENSE
CS
I
CS
L
= 0 V, so that
and
choice and that it
L
200 mA
L
by the current
Over−Current
.
(eq. 13)
(eq. 14)
http://onsemi.com
CS
CS
M
is
,
24
PFC Over−Power Limitation (OPL)
dependent. Sense current I
I
Input voltage signal V
The product (I
power (I
permissible level 275 mVA, the device turns off the PFC
driver so that the input power is limited. The OPL is
automatically deactivated when the product (I
lower than the 275 mVA level. This 275 mVA level
corresponds to the approximated input power (I
be smaller than the particular expression in Equation 15.
I
Where
CS
L
Figure 48. PFC Over−Power Limitation Configuration
I
I
This is a second OCP with a threshold that is line
When the product (I
L
L
and hence represents the input current approximately.
R
V
R
R
@ V
V
LBO
LBOU
SENSE
R
LBOL
in
CS
ac
L
t 275 mVA
t
x V
I
R
CS
ac
CS
SENSE
). It is illustrated in Figure 48.
R
K
x V
R
2 2 K
CS
LBO
R
C
CS
SENSE
LBO
@ K
LBO
LBO
@ p
I
LBO
CS
p
L
+
LBO
LBO
) represents an approximated input
CS
R
CS
represents the rms input voltage.
LBOU
@ V
@ 97 mVA
Current
represents the inductor current
mirror
x V
R
ac
LBOL
) R
LBO
t 275 mVA
LBOL
) is greater than a
> 275 mVA?
CS
L
x V
x Vac) to
(eq. 15)
LBO
OPL
) is