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PDF CM6805B Data sheet ( Hoja de datos )
| Número de pieza | CM6805B | |
| Descripción | 10-PIN Green-Mode PFC/PWM Combo CONTROLLER | |
| Fabricantes | Champion Microelectronic | |
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GENERAL DESCRIPTION
CM6805(A;B)/CM6806A
10-PIN Green-Mode PFC/PWM Combo CONTROLLER for High Density AC Adapter
FEATURES
The CM6805A and CM6806A are the Green-Mode
PFC/PWM Combo controller for High Density AC Adapter.
For the power supply, its input current shaping PFC
performance could be very close to the performance of the
CM6800 or ML4800 leading edge modulation average
current topology.
CM6805A/CM6806A offers the use of smaller, lower cost
bulk capacitors, reduces power line loading and stress on
the switching FETs, and results in a power supply fully
compliant to IEC1000-3-2 specifications. The CM6805A /
CM6806A includes circuits for the implementation of a
leading edge, input current shaping technique “boost” type
PFC and a trailing edge, PWM.
The CM6805A’s PFC and PWM operate at the same
frequency, 67.5kHz. A PFC OVP comparator shuts down
the PFC section in the event of a sudden decrease in load.
The PFC section also includes peak current limiting for
enhanced system reliability.
Both PFC and PWM have the Green Mode Functions.
When the load is below GMth, Green Mode Threshold,
PFCOUT is turned off. The GMth can be programmed by
the designer. PWM Green Mode will happen when the
PWMCMP (PWM Comparator) Duty Cycle is less than ~
6%, in the next cycle, the PWMOUT pulse will be removed
until PWMCMP Duty Cycle is greater than 6%, then the
next cycle, PWMOUT pulse appears.
PWM has a PWMtrifault pin which can sense the PWM
short and determine the GMth to turn off PFC.
Both PFC and PWM have the Green Mode to meet blue
angel and energy star spec.
10-Pin SOIC package
PWM pulse skipping for the green mode
Use RAC as the Startup resistor around 5 Mega Ohm at
IAC pin
It can use the HV bipolar to start up the chip and it helps
green mode.
Easy to configure into Boost Follower
Enable lowest BOM for power supply with PFC
Internally synchronized PFC and PWM in one IC
Patented slew rate enhanced voltage error amplifier with
advanced input current shaping technique
Universal Line Input Voltage
CCM boost or DCM boost with leading edge modulation
PFC using Input Current Shaping Technique
Feedforward IAC pin to do the automatic slope
compensation
PFCOVP, VCCOVP, Precision -1V PFC ILIMIT, PFC
Tri-Fault Detect comparator to meet UL1950
Low supply currents; start-up: 100uA typical, operating
current: 2mA typical.
Synchronized leading PFC and trailing edge modulation
PWM to reduce ripple current in the storage capacitor
between the PFC and PWM sections and to reduce
switching noise in the system
VINOK Comparator to guarantee to enable PWM when
PFC reach steady state
High efficiency trailing-edge current mode PWM
Exact 50% PWM maximum duty cycle
UVLO, REFOK, and brownout protection
Digital PFC and PWM soft start, ~10mS
Precision PWM 1.5V current limit for current mode
operation
PWMtrifault to sense DC to DC short and Turn off PFC at
GMth
PWMtrifault also can be programmed to do the Thermal
Protection
2006/10/11 Rev1.0
Champion Microelectronic Corporation
Page 1
1 page  
CM6805(A;B)/CM6806A
10-PIN Green-Mode PFC/PWM Combo CONTROLLER for High Density AC Adapter
ELECTRICAL CHARACTERISTICS (Conti.)Unless otherwise stated, these specifications apply
Vcc=+15V, RT = 52.3kΩ, CT = 470pF,TA=Operating Temperature Range (Note 1)
Symbol
Parameter
DC to DC Short
Test Conditions
PWM Tri-Fault Detect Comparator
Sweep PWMtrifault
Green Mode Threshold
Sweep PWMtrifault
Voltage Stability
Temperature Stability
Total Variation
PFC Dead Time (Note 2)
Minimum Duty Cycle
Maximum Duty Cycle
Output Low Rdson
Output Low Voltage
Output High Rdson
Output High Voltage
Rise/Fall Time (Note 2)
Duty Cycle Range
Output Low Rdson
Output Low Voltage
Output High Rdson
Output High Voltage
Rise/Fall Time (Note 2)
Start-Up Current
Operating Current
Undervoltage Lockout Threshold
Undervoltage Lockout Hysteresis
PFC Frequency
10V < VCC < 15V
Line, Temp (CM6805A)
Line, Temp (CM6805B)
Line, Temp (CM6806A)
PFC
IAC=100uA,VFB=2.55V, ISENSE = 0V
IAC=0uA,VFB=2.0V, ISENSE = 0V
IOUT = -100mA
IOUT = -10mA, VCC = 8V
IOUT = 100mA, VCC = 15V
CL = 1000pF
PWM
IC
IOUT = -100mA
IOUT = -10mA, VCC = 8V
IOUT = 100mA, VCC = 15V
CL = 1000pF
Supply
VCC = 11V, CL = 0
VCC = 15V, CL = 0
CM6805A/CM6806A
Min.
Typ.
Max.
VCC-0.9
VCC-0.1
-400mV+
(VCC-1.
4)/2
(VCC-1.4)
/2
+400mV
+(VCC-1
.4)/2
1
2
60 67 74.5
85 95 106
49 55 60
0.3 0.45 0.65
1
90 95
15 22.5
0.8 1.5
0.4 0.8
30 45
13.5 14.2
50
0-50
15 22.5
0.8 1.5
0.7 1.5
30 45
13.5 14.2
50
100 150
2 4.0
12.35 13 13.65
2.7 3 3.3
Unit
V
V
%
%
kHz
kHz
kHz
us
%
%
ohm
V
V
ohm
V
ns
%
ohm
V
V
ohm
V
ns
uA
mA
V
V
Note 1: Limits are guaranteed by 100% testing, sampling, or correlation with worst-case test conditions.
Note 2: Guaranteed by design, not 100% production test.
2006/10/11 Rev1.0
Champion Microelectronic Corporation
Page 5
5 Page 
CM6805(A;B)/CM6806A
10-PIN Green-Mode PFC/PWM Combo CONTROLLER for High Density AC Adapter
The ISENSE Filter is a RC filter. The resistor value of the
ISENSE Filter is between 100 ohm and 50 ohm. By selecting
RFILTER equal to 50 ohm will keep the offset of the IEAO less
than 5mV. Usually, we design the pole of ISENSE Filter at
fpfc/6, one sixth of the PFC switching frequency. Therefore,
the boost inductor can be reduced 6 times without
disturbing the stability. Therefore, the capacitor of the ISENSE
Filter, CFILTER, will be around 283nF.
IAC, RAC, Automatic Slope Compensation, DCM at high line
and light load, and Startup current
There are 4 purposes for IAC pin:
1.) For the leading edge modulation, when the duty
cycle is less than 50%, it requires the similar slope
compensation, as the duty cycle of the trailing
edge modulation is greater than 50%. In the
CM6805A/CM6806A, it is a relatively easy thing to
design. Use an more than 800K ohm resistor, RAC
to connect IAC pin and the rectified line voltage. It
will do the automatic slope compensation. If the
input boost inductor is too small, the RAC may
need to be reduced more.
2.) During the startup period, Rac also provides the
initial startup current, 100uA;therefore, the bleed
resistor is not needed.
3.) Since IAC pin with RAC behaves as a feedforward
signal, it also enhances the signal to noise ratio
and the THD of the input current.
4.) It also will try to keep the maximum input power to
be constant. However, the maximum input power
will still go up when the input line voltage goes up.
Start Up of the system, UVLO, VREFOK and Soft Start
During the Start-up period, RAC resistor will provide the start
up current~100uA from the rectified line voltage to IAC pin.
Inside of CM6805A/CM6806A during the start-up period,
IAC is connected to VCC until the VCC reaches UVLO
voltage which is 15V and internal reference voltage is
stable, it will disconnect itself from VCC. During the Start
up, the soft start function is triggered and the duration of the
soft start will last around 10mS.
PFC section wakes up after Start up period
After Start up period, PFC section will softly start since
VEAO is zero before the start-up period. Since VEAO is a
slew rate enhanced transconductance amplifier (see figure
3), VEAO has a high impedance output like a current
source and it will slowly charge the compensation net work
which needs to be designed by using the voltage loop gain
equation.
Before PFC boost output reaches its design voltage, it is
around 380V and VFB reaches 2.5V, PWM section is off.
PWM section wakes up after PFC reaches steady state
PWM section is off all the time before PFC VFB reaches
2.45V. Then internal 10mS digital PWM soft start circuit
slowly ramps up the soft-start voltage.
PFC OVP Comparator
PFC OVP Comparator sense VFB pin which is the same the
voltage loop input. The good thing is the compensation
network is connected to VEAO. The PFC OVP function is a
relative fast OVP. It is not like the conventional error amplifier
which is an operational amplifier and it requires a local
feedback and it make the OVP action becomes very slow.
The threshold of the PFC OVP is 2.5V+10% =2.75V with
250mV hysteresis.
PFC Tri-Fault Detect Comparator
To improve power supply reliability, reduce system
component count, and simplify compliance to UL1950 safety
standards, the CM6805A/CM6806A includes PFC Tri-Fault
Detect. This feature monitors VFB (Pin 5) for certain PFC
fault conditions.
In case of a feedback path failure, the output of the PFC
could go out of safe operating limits. With such a failure, VFB
will go outside of its normal operating area. Should VFB go
too low, too high, or open, PFC Tri-Fault Detect senses the
error and terminates the PFC output drive.
PFC Tri-Fault detect is an entirely internal circuit. It requires
no external components to serve its protective function.
VCC OVP and generate VCC
For the CM6805A/CM6806A system, if VCC is generated
from a source that is proportional to the PFC output voltage
and once that source reaches 17.9V, PFCOUT, PFC driver
will be off.
The VCC OVP resets once the VCC discharges below
16.4V, PFC output driver is enabled. It serves as redundant
PFC OVP function.
Typically, there is a bootstrap winding off the boost inductor.
The VCC OVP comparator senses when this voltage
exceeds 17.9V, and terminates the PFC output drive. Once
the VCC rail has decreased to below 16.4V the PFC output
drive be enabled. Given that 16V on VCC corresponds to
380V on the PFC output, 17.9V on VCC corresponds to an
OVP level of 460V.
It is a necessary to put RC filter between bootstrap winding
and VCC. For VCC=15V, it is sufficient to drive either a
power MOSFET or a IGBT.
2006/10/11 Rev1.0
Champion Microelectronic Corporation
Page 11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet CM6805B.PDF ] | |
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