ON Semiconductor’s variable frequency controllers include quasi-resonant and resonant controllers.
These controllers are used respectively in critical conduction mode quasi-resonant flyback converters
and half bridge resonant LLC converters. These topologies minimize EMI radiation, provide better
magnetic utilization and offer excellent power conversion efficiency - up to 90%. Our variable
frequency controllers combine the advantages of working directly off-line (with our proprietary
VHVIC technology) with the ability to drive an external high-voltage MOSFET of your choice, and
offer you more design flexibility than our competitors.
A 60 W Power Adapter
Using NCP1337
12 V
NTP75N06
OPTO-1
OPTO-2
SMPS
MOSFET
EMI
Filter
AC
NCP1337
SMPS
Controller
Synchronous
Rectification
Circuitry
12V
12V
OPTO-1
TL431
OPTO-2
12V
Key Features & Benefits
~
~
~
~
~
~
~
Quasi-resonant mode valley switching
i
Minimizes EMI
i
Reduces switching losses
High-voltage start-up-current source
i
Offers clean loss-less start-up sequence
Dynamic Self Supply (DSS) capability
i
Simplifies transformer design
Adjustable skip-mode and Soft-Skip™ capability
i
No acoustic noise generation
Gate drive capability up to 500 mA
i
Gives flexibility in choosing external MOSFET
Over-current and over-voltage protection
i
Protects circuitry
Over-power compensation
Flyback Quasi-Resonant
Controller Technology
for Increased Efficiency
and Lower EMI
Voltage Feedback
Over Voltage
Protection
VARIABLE
FREQUENCY
CONTROLLERS
Variable
t
off
Operating
Mode
Device
NCP1215A
NCP1351
NCP1205
NCP1207A
NCP1308
NCP1337
NCP1377/B
NCP1378
NCP1381
NCP1395
Max
Output
Power
1
(W)
10
50
150
150/100
1
150
200
150
150
200
500
Mode
Current, Var t
off
Current, Var t
off
Current
Current
Current
Current
Current
Current
Current
Voltage
Standby
Power
Method
Freq Foldback
Freq Foldback
Freq Foldback
Adj Skip Cycle
Adj Skip Cycle
Adj Skip Cycle
Adj Skip Cycle
Adj Skip Cycle
Adj Skip Cycle
Adj Skip Cycle
Output
Gate
Drive
(mA) @
V
CC
= 11V
30
150
300
500
500
500
500
500
500
180
Max
Switching
Frequency
(kHz)
Adjustable
65
Adj., Default 125
Set by Min, Toff = 8µs
Set by Min, Toff = 10µs
130
Set by Min, Toff = 3 or 8µs
Set by Min, Toff = 8µs
125
1000
500V Off-Line
Startup FET
Dynamic Self
Supply
Brown-Out
Soft-Start
Enable
Latch
OPC
3
OVP
2
Package(s)
SO-8, TSOP-6
SO-8
SO-16, PDIP-8, PDIP-14
SO-8, PDIP-8
SO-8
SO-7, PDIP-7
SO-7, PDIP-7
SO-7, PDIP-7
SO-14
SOIC-16, PDIP-16
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
Yes
EMI
Troubling?
Need higher
efficiency?
No
Quasi-
Resonant
Resonant
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
1. Maximum Power Output with DSS 2. Overvoltage Protection 3. Over Power Compensation
Page 4
Fixed Frequency Controllers
Low Cost and Low Power Consumption. . .
Fixed frequency controllers from ON Semiconductor are the perfect solution for many applications. DVD
players, set-top boxes, notebook power adapters, printers, scanners, LCD monitors, and a wealth of other end
products use our controllers. Extremely low standby power helps you easily meet applicable regulations. The
Dynamic Self-Supply (DSS) feature of our devices saves cost by avoiding the use of an auxiliary transformer
winding, and current-mode topologies give tighter control of output voltage. Our fixed frequency controllers
can help you meet your toughest design challenges while still keeping cost to a minimum.
Key Features & Benefits
~
Dynamic Self Supply (DSS) capability
i
No auxiliary transformer winding
~
Current-mode control with adjustable skip-cycle and Soft-
Skip™capability
i
Provides excellent efficiency at light loads
i
No acoustic noise generation
~
Fixed frequencies up to 200 kHz
i
Offers suitable solution for all applications
~
High-voltage start-up-current source
i
Clean loss less start-up sequence
HV Pin Handles Up to
500 V Directly
~
Frequency jittering
i
Reduces EMI signature
~
Go-to-standby for PFC front stage
i
Minimizes standby losses
~
Internal short–circuit protection independent of auxiliary voltage
i
Reliable short-circuit protection, immediately reducing the
output power
~
Under-voltage lockout at 7.6 V typical
i
Suitable for applications already using UC3843
+
AC
Input
EMI
Filter
Output
Voltage
−
Latch
Input
Latch Protection
skip/latch HV
FB
CS
V
CC
Gnd
Drv
HV Pin
Protection
Adjust
Skip
Level
Decoupling
Capacitors
NCP1271
NCP1271
Demo Board
Compensation
Ramp
Primary Current Limitation
Current-Mode Operation
NCP1271 Typical Schematic for Fixed Frequency Controller with Soft-Skip™
Ramp
Compensation
500V Off-Line
Starup FET
Freq Jittering
Dynamic Self
Supply
FIXED
FREQUENCY
CONTROLLERS
Device
Max
Output
Power
(W)
150/40
1
Mode
Current
Current
Current
Current
Current
Current
Current
Current
Voltage
Standby
Power
Method
Adj Skip
Adj Skip
Adj Skip
Adj Skip
Adj Skip
Adj Skip
Adj Skip
Adj Skip w/ TLD
5
Skip Cycle
Output
Gate Drive
(mA) @
V
CC
= 11V
250
250
250
500
500
500
500
500
200
Frequency
Options
(kHz)
40,60,100
60,100
40,60,100
65,100,133
65,100,133
Adj Up to 150
65,100,133
65,100
Adj Up to 1000
Brown-Out
Soft-Start
Enable
4
4
4
4
4
4
4
4
Latch
OVP
4
Package(s)
SO-8, PDIP-8
SO-8, PDIP-8
SO-8, PDIP-8
SO-8, PDIP-7
SO-7, PDIP-7
SO-8, PDIP-8
SO-8, PDIP-8
SO-7
SO-16
Low End
Yes
Do you
need low
Standby
power?
No
What
features
do you
need?
High End
NCP1200
NCP1201
150
NCP1203
150
NCP1216/A
2
150/100
1
NCP1217/A
2
150
NCP1212
150
NCP1230
150
NCP1271
150
NCP1282/1562*
400
4
4
4
4
4
4
4*
4
4
4
4
4
4
4
4
4
4
4
4
4
4
3
4
3
4
4
4
4
4
4
4
4
4
EXT
EXT
EXT
INT
INT
EXT
INT
INT
EXT
4
4
1. Maximum power output with DSS 2. “A” Versions Have a 50% Max Duty Cycle for Forward Topologies 3. Only Available on “A” Versions 4. Overvoltage Protection 5. Transient Load Detection * NCP1562 has 100 V startup FET
Please visit our website at www.onsemi.com for additional options.
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