NCP1200AD100R2 ON Semiconductor, NCP1200AD100R2 Datasheet - Page 7

• Manufacturer Part Number: NCP1200AD100R2
• Description: IC CTRLR PWM CM HV 8SOIC
• Manufacturer: ON Semiconductor

Specifications of NCP1200AD100R2

• Output Isolation: Isolated
• Frequency Range: 90 ~ 114kHz
• Voltage - Input: 12.1 ~ 16 V
• Operating Temperature: 0°C ~ 150°C
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: NCP1200AD100ROSTR

Introduction
architecture where the switch−off time is dictated by the
peak current setpoint. This component represents the ideal
candidate where low part−count is the key parameter,
particularly in low−cost AC−DC adapters, auxiliary
supplies, etc. Due to its high−performance High−Voltage
technology, the NCP1200A incorporates all the necessary
components normally needed in UC384X based supplies:
timing components, feedback devices, low−pass filter and
self−supply. This later point emphasizes the fact that
ON Semiconductor’s NCP1200A does NOT need an
auxiliary winding to operate: the product is naturally
supplied from the high−voltage rail and delivers a V
IC. This system is called the Dynamic Self−Supply (DSS).
Dynamic Self−Supply
V
can easily describe the current source operation with a bunch
of simple logical equations:
POWER−ON: IF V
ON, no output pulses
IF V
output is pulsing
IF V
output is pulsing
Typical values are: VCC
sketch offers the necessary light:
Current
Source
CC
The NCP1200A implements a standard current mode
The DSS principle is based on the charge/discharge of the
To better understand the operational principle, Figure 15’s
V
CC
CC
CC
Figure 15. The charge/discharge cycle over a
bulk capacitor from a low level up to a higher level. We
decreasing > VCC
increasing < VCC
10.0 M
V
ripple
= 2 V
10 mF V
30.0 M
CC
< VCC
ON
H
L
H
CC
= 12 V, VCC
UVLO
THEN Current Source is OFF,
THEN Current Source is ON,
capacitor
50.0 M
OUTPUT PULSES
H
H
THEN Current Source is
= 12 V
UVLO
L
70.0 M
= 10 V
L
= 10 V
OFF
APPLICATION INFORMATION
CC
90.0 M
http://onsemi.com
to the
7
consumption and the MOSFETs gate charge Qg. If we select
a MOSFET like the MTP2N60E, Qg max equals 22 nC.
With a maximum switching frequency of 68 kHz for the P60
version, the average power necessary to drive the MOSFET
(excluding the driver efficiency and neglecting various
voltage drops) is:
F
F
Qg = MOSFETs gate charge
V
V
consumption at no−load will therefore heavily rely on the
internal IC consumption plus the above driving current
(altered by the driver’s efficiency). Suppose that the IC is
supplied from a 350 VDC line. The current flowing through
pin 8 is a direct image of the NCP1200A consumption
(neglecting the switching losses of the HV current source).
If ICC2 equals 2.3 mA @ T
dissipated (lost) by the IC is simply: 350 x 2.3 m = 805 mW.
For design and reliability reasons, it would be interesting to
reduce this source of wasted power which increases the die
temperature. This can be achieved by using different
methods:
SW
SW
CC
CC
The DSS behavior actually depends on the internal IC
To obtain the final IC current, simply divide this result by
1. Use a MOSFET with lower gate charge Qg
2. Connect pin through a diode (1N4007 typically) to
3. Permanently force the V
: I
⋅ Qg ⋅ V
= maximum switching frequency
= V
one of the mains input. The average value on pin 8
becomes
contribution example drops to: 223 x 2.3 m = 512
mW. If a resistor is installed between the mains and
the diode, you further force the dissipation to
migrate from the package to the resistor. The
resistor value should account for low−line startup.
an auxiliary winding. It will automatically
disconnect the internal startup source and the IC
will be fully self−supplied from this winding.
Again, the total power drawn from the mains will
significantly decrease. Make sure the auxiliary
voltage never exceeds the 16 V limit.
driver
GS
= F
level applied to the gate
CC
SW
V MAINS(peak) @ 2
with
⋅ Qg = 1.5 mA. The total standby power
p
CC
J
= 25°C, then the power
level above VCC
. Our power
H
with