R2A20115 Datasheet, PDF (1/1 Pages) Renesas Technology Corp – Continuous Conduction Mode PFC IC

Renesas Continuous Conduction Mode PFC IC
R2A20115 with High Accurate Constant Power Limiter
Rev.6.0
April 2010
Features
• No reference voltage adjustment resistor is needed with higher accurate built-in circuit (+/-1.6%) than previous products (+/-2%).
• No margin for inductor design is needed with higher accuracy of detect level of the built-in over current protection circuit. (Previously,
the margin can not be omitted for its lower accuracy)
• Prevention of “coil vibration” at starting-up or over current period by the function of
power limiter. (Previously, it’s not supported)
• The function of power limiter cuts down unnecessary power supplied to the next
stage. (Previously, the higher AC input voltage is applied, the higher power can be
supplied to the next stage, of which power supply might be heavily loaded unnecessarily.)
• Prevention of overshoot on output voltage by dynamic OVP function without specific
Pins. (Previously, this function is not supported or partly supported using specific Pins)
• Power dissipation is cut down by 35% of comparable products.
OUT
GND
DELAY
CGND
CAI
VREF
CAO
CLIMIT
DIP16
or
SOP16
VCC
SS
EO
FB
IAC
PFC-ON
CT
RT
• Easy system design by using calculation sheet in Excel format provided for customers.
1-1. Introduction of Constant Power Limiter
1-2. Introduction of Constant Power Limiter and Reduction of
Using Current Monitoring and Setting Pins Separately Needless Device Margin by the Improvement of it’s Accuracy
Conventional
Multiplier
CS Current amplifier
Over-current limiter
R2A20115
Voltage amplifier
FB
Constant
power limiter
EO
CAI ^Multiplier
VREF
Current amplifier
6000
5000
4000
3000
2000
1000
Input Ef f ectiv e Power v s Input AC Voltage
R有2効A2電01力15(R[W2]A20115) [W]
U_過s_電ing_流o_検nly_出O_のve_みr C_電u_力rre_制nt_限Li₍m_計it_算er_値(ca₎ lculated) [W]
“Coil vibration” is prevented by
gradual/steady control when over
current occurs.
CLIMIT
Over-current limiter
0
0
50
100
150
200
250
300
Constant power limiter is effectively
working independently of input voltage
Input AC v oltage [V]
1-3. Reduction of Maximum Current in Boost Inductor by Improved Accuracy of Power Limiter and Current Limiter
Input AC Current
Current limiter
accuracy
R2A20111
Current Limiter
Input AC Current
R2A20115
Current Limiter
Cut the extra margin by minimizing the
peak current distribution of inductor
due to high accuracy power limiter
and current limiter function.
Power Limiter
accuracy
Vcl=+/-78mv
Power Limiter
Vcl=+/-15mv
Power Limiter
Inductor
Inductor
Input
AC Voltage
2. Improvement of Load Regulation by Utilizing gm AMP in Feedback Loop
Input
AC Voltage
3. Hold Function at Brownout
In case voltage amplifier is feedback type, the current via
feedback resister influences load regulation. By using gm
amplifier, there is no current path in the circuit. So that,
load regulation can be improved.
Competitor’s
R2A20115
Additionally, contributed by the improvement
in accuracy of circuit (2% to 1.6%), the
resister to adjust the reference voltage
becomes unnecessary.
VOUT
VEO
AC Input
Brownout
Brownout
Hold Counter
PFC Output voltage
Detection level
Detection level
Hold time can be adjusted.
VOUT
VOUT
1.6%
2%
FET OUT
(R2A20115)
R2
Error AMP
R1
VEO
VREF
R2
FB Error AMP
R1
VREF
FFiinnaall aaddjjuussttmmeenntt ooff rreessiisstteerr
iiss nnoott nneeeeddeedd..
5
4
VEO 3
2
1
Io
By hold function, the IC keeps
working if the duration of
brownout is shorter than the
preset hold time. So that it can
recover rapidly.
The IC restarts safely with
soft-start mode if the
duration of brownout is
longer than the preset
hold time.
4. Prevention of “Coil Vibration” and Overshooting Contributed by Dynamic OVP
The IC newly integrates Dynamic OVP circuit, which limits peak current by making
the width of OUT pulse narrower gradually and then prevents over voltage, when
over voltage is detected, in addition to Static OVP circuit, which stops the output
pulse. Even if overshooting occurs in transition period,
such as the period of start-up or sudden variation of
load, Dynamic OVP keeps the output pulse on, so that,
“coil vibration” can be prevented.
Operations just after sudden variation of load <0.1A-1.3A>
Error Amp Block
Dynamic
OVP
Renesas Electronics
URL http://www.renesas.com/pfcic
With Dynamic OVP
©2010. Renesas Electronics Corporation, All rights reserved.
Without Dynamic OVP