energy-efficient pwm controller with peak power excursion...
TRANSCRIPT
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www.onsemi.cn
Energy-efficient PWM Controller with
Peak Power Excursion NCP1254/5
具备瞬时功率功能的高能效
PWM控制器NCP1254/5
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We have parts for
all of these
Topologies
forward flyback
half-bridge
push-pull
full-bridge
2-transistor forward
3
Wide Portfolio of Controller Solutions
Output
Power
Relative
Performance
90W 150W 200W+
NCP1246 Fixed Freq. Flyback
NCP1380 Quasi Resonant Flyback
NCP1398 Resonant Half Bridge Controller
NCP1652A Flyback for single stage PFC
Incorporating PFC
Continuing to develop
higher performing
devices that reduce
cost and improve size
and efficiency
40W
NCP1250 6 pin Controller
4
AC-DC Fixed Frequency Flyback
Controller Evolution
2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 |
NCP1200
NCP1203
- w/o DSS
NCP1216
- Soft-Start
- Ramp Comp
NCP1217
- w/o DSS
1st Generation
High Voltage
Controllers
Fe
atu
res a
nd
Effic
ien
cy
3rd Generation
Major Leap in Light
Load Efficiency
4th Generation
Improved No Load
Power Consumption
NCP1237
-Dual OCP
-AC OVP
NCP1238
- No Dual OCP
NCP1288
- No Dss
NCP1236
-No Dual OCP
NCP1234
- w/o Brown Out
NCP1250
-No HV
NCP1251
-Vcc OVP
2nd Generation
Advance Protection
Features
NCP1230 - PFC Stby
Industry first AC-DC
controllers with Direct
Connection to High
Voltage Line
-Timer Based Over Current
Protection
-Latch Fault Protection
-Frequency Foldback
-Brown Out Protection
-Overpower Compensation
-X2 Capacitor Discharge
-Low Consumption Off
Mode
NCP1246
NCP1244
- w/o Brown Out
NCP1219
NCP1271
- w/o DSS
NCP4354 - No Load
Detection
Dynamic Self Supply –
No need for Auxiliary
Winding
Introduction of Skip Mode
NCP1247 NCP1249
NCP1255
- Peak Power
NCP1254
-No BO
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Low Standby Product Roadmap N
o L
oa
d S
tan
db
y P
ow
er
NCP1246/47 • Active X2 Discharge
• Off Mode
| 2011 | 2012 | 2013
NCP4354 • No Load
Detection
< 30 mW (230Vac)
< 10 mW (230Vac)
< 5 mW (230Vac)
NCP1937 • Active X2 Discharge
• Improved Off Mode
NCP4355 • No Load
Detection
NCP1249 • Active X2 Discharge
• Off Mode
• Improved ICC
NCP4354 • No Load
Detection
NCP4352 • ECO Mode
NCP1250/1/3 • Low Icc, Low Istart
NCP124x • Improved ICC
• Improved BO Divider
NCP4355 • No Load
Detection
NCP1249 • Active X2 Discharge
• Off Mode
• Improved ICC
NCP431 •Standard
NCP1254/5 • Peak Power
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NCP1255 Fixed Frequency PWM Controller
with Peak Power Excursion
The NCP1255 is a fixed frequency, PWM controller designed for applications requiring a peak power capability. It
includes frequency foldback and skip cycle to ensures a high efficiency design across the entire load range.
• 65 kHz frequency with
130kHz during peak power
• Frequency Foldback with
Skip Mode
• Adjustable Brown Out
Protection
• Adjustable dual timer OCP
• Vcc OVP
• Peak power capability
without large transformer
• Improved light-load
efficiency
• Improved protection
• Adjustable Over Power Protection
• Frequency Jittering in normal and frequency foldback
• Internal 4 ms soft-start
• Low no-load standby power
• Double Vcc hiccup for reduced power in fault
• Printer power supplies
• AC-DC Adapters
• Game console adapters
Market & Applications
Other Features
Ordering & Package Information
Part Number Frequency OCP
NCP1255AD65R2G 65 kHz Latched
NCP1255BD65R2G 65 kHz Auto-Recovery
Eris
Vbulk
..
ramp
comp.
OPP
Vout
OVP
.
1
2
3
4 5
8
6
7
Eris
BO
Benefits
Value Proposition
Unique Features
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• Fixed frequency peak-current mode control
• Frequency foldback down to 26 kHz in light load conditions
• Frequency jittering from full load to skip-cycle
• Skip-cycle operation in no-load conditions
• Adjustable slope compensation for Continuous Conduction Mode
• Non-dissipative proprietary OPP compensation
• Latch input for OVP and OTP implementations
• 15-µA maximum start-up current
• 4-ms internal soft-start sequence
• Adjustable timer-based short-circuit protection
• Auto-recovery or Latched
• 130 kHz frequency excursion for peak power requirements
• Adjustable Brown Out Protection
• Vcc supply up to 35 V
• 100% to 25% timer reduction from overload to short-circuit fault
• Double Vcc hiccup for reduced average power in fault mode
Feature Overview
Upgraded
Features
8
Eris
Vbulk
..
ramp
comp.
OPP
Vout
OVP
.
1
2
3
4 5
8
6
7
Eris
BO
NCP1255 Typical Schematic
OPP /
Latch
FB
CS
GND
Timer
Vcc
DRV
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Peak Power Excursion
Many power supplies now have requirements for both nominal power
and peak power. For example, 60W nominal with 90W peak.
The peak power is only required in short bursts. Rather than design the
power supply for 90W continuous power, we can use advanced control
techniques to meet these requirements.
These controllers increase the switching frequency for a short duration
(<1s) while keeping the peak current at a fixed value.
This allows for increased power delivery without increasing the size of the
transformer, lowering costs and minimizing form factor!
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2out p peak swP L I F
@130kHz 2 @65kHzout outP P
65 kHz
130 kHz
nominal
peak
x2
*For DCM Operation
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NCP1255 Peak Power Excursion
When feedback voltage increases above 3.2V, the switching frequency
increases until it doubles at VFB=4.0V. Peak current remains frozen.
This allows the SMPS to deliver more power without growing transformer
size
Fsw
VFB
VCS
VFB
65 kHz
26 kHz
400 mVVfold
3.2 V Vfold 3.2 V
0.8 V
0.47 V
FB
Vfreeze
0.25 V
1 V 1.9 V
1.9 V
max
min
max
min
Vfold,end
Frequency Peak current setpoint
130 kHz
4 V Vskip
0.4 V
1.5 V
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Overload Timer for Peak Power
The peak power duration is limited by the overload timer
The nominal overload timer is adjustable (up to 1 second)
There are dual levels for the overload timer, dependent of the FB voltage
The timer is divided by 4 when a short circuit is detected
VFB (V)
t
4.0
3.2
Open loop voltage
100% timer – overload
25% timer – short-circuit
65 kHz
130 kHz
Fixed-frequency variable peak current
26 kHz
Max Ipeak
31% max Ipeak
Skip cycle0.4
1
4.5 max
1.91.5 Frequency foldback variable peak current
65 kHz
Frozen peak current
Frozen current Fixed frequency variable peak current
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Dual Level Overload / Short Circuit
When 3.2 V < VFB < 4.0 V, an overload condition is detected
When VFB > 4.0 V, a short circuit is detected and the fault timer is decreased
to 25%
* Actual OVL/SC thresholds are lower when using OPP. For example, with an
OPP level of -200 mV, the OVL threshold becomes (0.8 – 0.2) x 4 = 2.4 V
VFB
4.0 V
3.2 V
VFB
4.0 V
3.2 V
fault fault
VCt
OVLSC
SCOVLSCOVL
130 kHz
65 kHz
130 kHz
65 kHz
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Brown Out Protection
A simple comparator monitors the input voltage on the BO pin. When line
voltage is too low, pulses are stopped and the Vcc hiccups
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Brown Out Design Equations
The hysteresis is fixed by the internal ratio VBOon/VBOoff = 1.33
Select the bridge current. Say 10 µA. Then R2 is:
2
0.880kΩ
10
BOon
bridge
VR
I u
,
1
1100.8
3.14 3.4MΩ10
in onBOon
bridge
VV
RI u
The turn-off voltage will then be:
7758Vrms
1.33 1.33
BOonBOoff
VV
Turn-on
is 77 V
rms
2R
1R
BO
Half-wave
rectification
1μF
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Brown Out Protection
The Brown Out recovery is always synchronized with the Vcc signal
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Double Vcc Hiccup
During a fault, driving pulses are stopped and Vcc drops to Vcc(min)
At Vcc(min) the controller consumption drops to a few uA and the Vcc recharges by
the resistive staring network
When Vcc reaches Vcc(on) the controller purposely ignores the re-start and waits for
another Vcc cycle
This lowers the duty ratio, reducing average input power during fault conditions
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Double Vcc Hiccup w/ Brown Out
If a Brown Out transition is detected, the double hiccup is interrupted and
the controller re-starts at the next Vcc(on) in order to shorten the re-start
time
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NCP1254 Fixed Frequency PWM Controller
with Peak Power Excursion in tiny TSOP-6
The NCP1254 is a fixed frequency, PWM controller in TSOP-6 designed for applications requiring a peak power
capability. It includes frequency foldback and skip cycle to ensures a high efficiency design across the entire load range.
• 65 kHz frequency with
130kHz during peak power
• Frequency Foldback with
Skip Mode
• Adjustable Over Power
Protection
• Fixed dual timer OCP
• Peak power capability
without large transformer
• Improved light-load
efficiency
• Improved protection
• Vcc OVP
• Frequency Jittering in normal and frequency foldback
• Internal 4 ms soft-start
• Low no-load standby power
• Double Vcc hiccup for reduced power in fault
• Printer power supplies
• AC-DC Adapters
• Game console adapters
Market & Applications
Other Features
Ordering & Package Information
Part Number Frequency OCP
NCP1254ASN65T1G 65 kHz Latched
NCP1254BSN65T1G 65 kHz Auto-Recovery
1
2
3
6
4
5
NCP125x
Vbulk
..
rampcomp.
OPP
Vout
OVP
.
Value Propositions
Unique Features Benefits
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NCP1254 Typical Schematic
OPP /
Latch
FB
CS
GND
Vcc
DRV 1
2
3
6
4
5
NCP125x
Vbulk
..
rampcomp.
OPP
Vout
OVP
.
NCP1254
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NCP1254 vs NCP1255 Feature Comparison
NCP1254 NCP1255
Fault Timer 200ms Fixed Adjustable
Brown Out No Yes
Device Options Latch (A version)
Auto-Recovery (B version)
Latch (A version)
Auto-Recovery (B version)
Package TSOP-6 SOIC-8
Operating Frequency 65kHz->130kHz 65kHz->130kHz
1
2
3
4 5
8
6
7
DRV
Vcc
BO
Gnd
CS
FB
OPP
Latch Timer
NC
P1
25
5 1
2
3
6
4
5
OPP/Latch
FB
CS
GND DRV
Vcc
NC
P1
25
4
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Demoboard
• Vin = 100 – 240 Vrms, Vout = 32 V
• Pout = 25W nominal, 41W peak
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Demoboard Efficiency
WoutP
%
100VrmsinV
230VrmsinV
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Peak Power Performance
outv t
100 V rmsinV FBv t
,
0.5 A
1.1A
out
out peak
I
I
outv t
100 V rmsinV FBv t
1.15
3.5%
V
,
0.5 A
1.3 A
out
out peak
I
I
Overload Region - 35W for 100ms Short Region - 41W for <50ms