NCP1378P ON Semiconductor, NCP1378P Datasheet - Page 12
NCP1378P
Manufacturer Part Number
NCP1378P
Description
IC CTRLR PWM CM OVP UVLO 8DIP
Manufacturer
ON Semiconductor
Datasheet
1.NCP1378DR2.pdf
(15 pages)
Specifications of NCP1378P
Pwm Type
Current Mode
Number Of Outputs
1
Frequency - Max
100kHz
Voltage - Supply
8.2 V ~ 18 V
Buck
No
Boost
No
Flyback
Yes
Inverting
No
Doubler
No
Divider
No
Cuk
No
Isolated
No
Operating Temperature
0°C ~ 125°C
Package / Case
8-DIP (0.300", 7.62mm), 7 Leads
Frequency-max
100kHz
Output Voltage
16 V
Output Current
500 mA
Mounting Style
Through Hole
Switching Frequency
100 KHz
Maximum Operating Temperature
+ 150 C
Fall Time
20 ns
Rise Time
40 ns
Synchronous Pin
No
Topology
Flyback
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Duty Cycle
-
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
Other names
NCP1378POS
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
NCP1378PG
Manufacturer:
ON/安森美
Quantity:
20 000
Soft- -Start
soften the constraints occurring in the power supply during
startup. It is activated during the power on sequence. As
soon as V
increased from nearly zero up to the maximum clamping
level (e.g. 1.0 V). The Soft- - Start is also activated during
the overcurrent burst (OCP) sequence. Every restart
attempt is followed by a Soft- - Start activation. Generally
speaking, the Soft- - Start will be activated when V
up either from zero (fresh power–on sequence) or 5.5 V, the
latch–off voltage occurring during OCP.
Calculating the Vcc Capacitor
consumption as soon as V
a NCP1378 is used and drives a MOSFET with a 30 nC
total gate charge (Qg). The total average current is thus
made of ICC1 (1.0 mA) plus the driver current, Fsw x Qg
or 1.8 mA. The total current is therefore 2.8 mA. The ΔV
available to fully startup the circuit (e.g. never reach the
7.5 V UVLO during power on) is 8.4 – 7.5 = 0.9 V. We have
a capacitor that then needs to supply the NCP1378 with
2.8 mA during a given time until the auxiliary supply takes
over. Suppose that this time was measured at around 10 ms.
CV
31.1 mF. Select a 47 mF/25 V and this will fit. During the
latchoff phase, the current consumption drops to 220 mA.
We can now calculate how long this latchoff phase will last:
(7.5–5.5) x 47 m/220 u = 427 ms.
The NCP1378 features an internal 1.0 ms Soft- - Start to
The V
CC
is calculated using the equation
CC
CC
capacitor can be calculated knowing the IC
reaches VCC
CC
ON
reaches VCC
Vcc
, the peak current is gradually
Figure 27. Typical Waveforms in Short Circuit Conditions
ON
C =
ON
. Suppose that
Vcc
Δt · i
ΔV
OFF
CC
or C ≥
Vcc
http://onsemi.com
ramps
latch
12
Protecting Pin 8 Against Negative Spikes
negative voltages that could appear on its pins. To avoid
any adverse latchup of the IC, we strongly recommend to
insert a resistor in series with pin8. This resistor prevents
from adversely latching the controller in case of negative
spikes appearing on the bulk capacitor during the
power- - off sequence. A typical value of 6.8 kΩ/0.5 W is
suitable. This resistor does not dissipate any power since it
only sees current during the startup sequence and during
overload.
Operating Shots
Vin = 120 VDC with a transformer featuring a 800 mH
primary inductance.
As any CMOS controller, NCP1378 is sensitive to
Below are some oscilloscope shots captured at
Driving Pulses
Vcc