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Número de pieza | NCP1379 | |
Descripción | Quasi-Resonant Current-Mode Controller | |
Fabricantes | ON Semiconductor | |
Logotipo | ||
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Quasi-Resonant
Current-Mode Controller for
High-Power Universal
Off-line Supplies
The NCP1379 hosts a high−performance circuitry aimed to
powering quasi−resonant converters. Capitalizing on a proprietary
valley−lockout system, the controller shifts gears and reduces the
switching frequency as the power loading becomes lighter. This
results in a stable operation despite switching events always occurring
in the drain−source valley. This system works down to the 4th valley
and toggles to a variable frequency mode beyond, ensuring an
excellent standby power performance.
The controller includes an Over Power Protection circuit which
clamps the delivered power at high−line. Safety−wise, a fixed internal
timer relies on the feedback voltage to detect a fault. Once the timer
elapses, the controller stops and enters auto−recovery mode, ensuring
a low duty−cycle burst operation. To further improve the safety of the
power supply, the NCP1379 features a pin to implement a combined
brown−out/overvoltage protection.
Particularly well suited for TVs power supply applications, the
controller features a low startup voltage allowing the use of an
auxiliary power supply to power the device.
Features
• Quasi−Resonant Peak Current−Mode Control Operation
• Valley Switching Operation with Valley−Lockout for Noise−Immune
Operation
• Frequency Foldback at Light Load to Improve the Light Load
Efficiency
• Adjustable Over Power Protection
• Auto−Recovery Output Short−Circuit Protection
• Fixed Internal 80 ms Timer for Short−Circuit Protection
• Combined Overvoltage Protection and Brown−out
• +500 mA / −800 mA Peak Current Source/Sink Capability
• Internal Temperature Shutdown
• Direct Optocoupler Connection
• Low VCC(on) Allowing to Use a Standby Power Supply to Power the
Device
• Extremely Low No−Load Standby Power
• SO8 Package
• These Devices are Pb−Free and are RoHS Compliant
Typical Applications
• High Power ac−dc Converters for TVs, Set−Top Boxes etc.
• Offline Adapters for Notebooks
This document contains information on a product under development. ON Semiconductor
reserves the right to change or discontinue this product without notice.
http://onsemi.com
QUASI−RESONANT PWM
CONTROLLER FOR HIGH
POWER AC−DC WALL
ADAPTERS
8
1
SOIC−8
D SUFFIX
CASE 751
MARKING
DIAGRAMS
8
1379
ALYW
G
1
1379
A
L
Y
W
G
= Specific Device Code
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb−Free Package
PIN CONNECTIONS
ZCD 1
FB 2
CS 3
GND 4
8 CT
7 FAULT
6 VCC
5 DRV
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 21 of this data sheet.
© Semiconductor Components Industries, LLC, 2009
December, 2009 − Rev. P0
1
Publication Order Number:
NCP1379/D
1 page NCP1379
ELECTRICAL CHARACTERISTICS (Unless otherwise noted: For typical values TJ = 25°C, VCC = 12 V, VZCwDw=w0.DVa, VtaFSBh=e3etV4,U.com
VCS = 0 V, Vfault = 1.5 V, CT = 680 pF) For min/max values TJ = −40°C to +125°C, Max TJ = 150°C, VCC = 12 V)
Symbol
Parameter
Conditions
Min Typ Max Unit
CURRENT COMPARATOR − CURRENT SENSE
VOPP(MAX) Setpoint decrease for VZCD = −300 mV (Note 5)
VCS(stop)
Threshold for immediate fault protection activation
tBCS
Leading Edge Blanking Duration for VCS(stop)
DRIVE OUTPUT − GATE DRIVE
VZCD = −300 mV, VFB =
4 V, VCS increasing
35.0 37.5 40.0
1.125
−
1.200
120
1.275
−
%
V
ns
RSNK
RSRC
ISNK
ISRC
tr
Drive Resistance
DRV Sink
DRV Source
Drive current capability
DRV Sink
DRV Source
Rise Time (10 % to 90 %)
VDRV = 10 V
VDRV = 2 V
− 12.5 −
− 20 −
W
VDRV = 10 V
VDRV = 2 V
mA
− 800 −
− 500 −
CDRV = 1 nF, VDRV from 0
to 12 V
−
40 75 ns
tf Fall Time (90 % to 10 %)
CDRV = 1 nF, VDRV from 0
to 12 V
−
25 60 ns
VDRV(low)
DRV Low Voltage
VCC = VCC(off) + 0.2 V
CDRV = 1 nF, RDRV=33 kW
VDRV(high)
DRV High Voltage (Note 6)
VCCCDR=VV=CC1(MnFAX)
DEMAGNETIZATION INPUT − ZERO VOLTAGE DETECTION CIRCUIT
8.4
10.5
9.1
13.0
−
15.5
V
V
VZCD(TH)
VZCD(HYS)
VCH
VCL
tDEM
ZCD threshold voltage
ZCD hysteresis
Input clamp voltage
High state
Low state
Propagation Delay
VZCD decreasing
VZCD increasing
Ipin1 = 3.0 mA
Ipin1 = −2.0 mA
VZCD
decreasing from
to −0.3 V
4
V
35
15
8
−0.9
−
55
35
10
−0.7
150
90
55
12
−0.3
250
mV
mV
V
ns
CPAR
Internal input capacitance
tBLANK
Blanking delay after on−time
toutSS
tout
Timeout after last demag transition
RZCD(pdown) Pulldown resistor (Note 3)
TIMING CAPACITOR − TIMING CAPACITOR
− 10 − pF
2.30 3.15 4.00 ms
During soft−start
28 41 54 ms
After the end of soft−start
5.0
5.9
6.7
140 320 500 kW
VCT(MAX)
ICT
VCT(MIN)
Maximum voltage on CT pin
Source current
Minimum voltage on CT pin, discharge switch
activated
VFB < VFB(TH)
VCT = 0 V
5.15 5.40 5.65
V
18 20 22 mA
− − 90 mV
CT Recommended timing capacitor value
FEEDBACK SECTION − FEEDBACK
220 pF
RFB(pullup)
Internal pullup resistor
15 18 22 kW
Iratio Pin FB to current setpoint division ratio
3.8 4.0 4.2
VFB(TH)
FB pin threshold under which CT is clamped to
VCT(MAX)
0.26 0.30 0.34
V
3. Guaranteed by design
4. The peak current setpoint goes down as the load decreases. It is frozen below Ipeak(VCO) (Ipeak = cst)
5. If negative voltage in excess to −300 mV is applied to ZCD pin, the current setpoint decrease is no longer guaranteed to be linear
6. Minimum value for TJ = 125°C
http://onsemi.com
5
5 Page NCP1379
NCP1379 OPERATING MODES
www.DataSheet4U.com
NCP1379 has two operating mode: quasi−resonant
operation and VCO operation for the frequency foldback.
The operating mode is fixed by the FB voltage as
portrayed by Figure 22:
• Quasi−resonant operation occurs for FB voltage higher
than 0.8 V (FB decreasing) or higher than 1.4 V (FB
increasing) which correspond to high output power and
medium output power. The peak current is variable and
is set by the FB voltage divided by 4.
• Frequency foldback or VCO mode occurs for FB
voltage lower than 0.8 V (FB decreasing) or lower than
1.4 V (FB increasing). This corresponds to low output
power.
• During VCO mode, the peak current decreases down to
17.5% of its maximum value and is then frozen. The
switching frequency is variable and decreases as the
output load decreases.
• The switching frequency is set by the end of charge of
the capacitor connected to the CT pin. This capacitor is
charged with a constant current source and the
capacitor voltage is compared to an internal threshold
fixed by FB voltage. When this capacitor voltage
reaches the threshold the capacitor is rapidly discharged
down to 0 V and a new period start.
Figure 22. Operating Valley According to FB Voltage
VALLEY DETECTION AND SELECTION
The valley detection is done by monitoring the voltage of
the auxiliary winding of the transformer. A valley is detected
when the voltage on pin 1 crosses down the 55 mV internal
threshold. When a valley is detected, an internal counter is
incremented. The operating valley (1st, 2nd, 3rd or 4th) is
determined by the FB voltage as shown by Figure 22.
http://onsemi.com
11
11 Page |
Páginas | Total 22 Páginas | |
PDF Descargar | [ Datasheet NCP1379.PDF ] |
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