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PDF R7731A Data sheet ( Hoja de datos )
| Número de pieza | R7731A | |
| Descripción | Burst Triple-Mode PWM Flyback Controller | |
| Fabricantes | RICHPOWER | |
| Logotipo |  |
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R7731A
Burst Triple-Mode PWM Flyback Controller
General Description
The R7731A is a high-performance, low cost, low start-up
current and current mode PWM controller with burst triple-
mode to support green mode power saving operation. The
R7731A integrates functions of soft start, Under VoItage
LockOut (UVLO), Leading Edge Blanking (LEB), Over
Temperature Protection (OTP) and internal slope
compensation. It provides the users a superior AC/DC
power application of higher efficiency, low external
component counts and lower cost solution.
To protect the external power MOSFET from being
damaged by supply over voltage, the R7731A output driver
is clamped at 12V. Furthermore, R7731A features fruitful
protections like Over Load Protection (OLP) and Over
Voltage Protection (OVP) to eliminate the external
protection circuits and provide reliable operation. R7731A
is available in SOT-23-6 and DIP-8 packages.
Applications
Adaptor and Battery Charger
ATX Standby Power
Set-Top Box (STB)
DVD and CD(R)
TV/Monitor Standby Power
PC Peripherals
Typical Application Circuit
Features
Very Low Start-up Current (<30uA)
10/14V UVLO
Soft Start Function
Current Mode Control
Jittering Switching Frequency
Internal Leading Edge Blanking
Built-in Slope Compensation
Burst Triple-Mode PWM for Green-Mode
Cycle-by-Cycle Current Limit
Feedback Open Protection
Over Voltage Protection
Over Temperature Protection
Over Load Protection
Soft Driving for Reducing EMI
High Noise Immunity
Opto-Coupler Short Protection
RoHS Compliant and Halogen Free
AC Mains
(90V to 265V)
VO+
VO-
RT VDD
R7731A
COMP
GATE
GND
CS
#
R7731A-07 Mar 2010
# See Application Information
1
1 page  
R7731A
Parameter
Frequency Jittering Range
Symbol
Conditions
PWM Frequency Jitter Period
Maximum Duty Cycle
Frequency Variation Versus VDD
Deviation
Frequency Variation Versus
Temperature Deviation
COMP Input Section
TJIT
DM AX
fDV
fDT
For 65 kHz
VDD = 12V to 25V
TA = −30°C to 105°C (Note 5)
Open Loop Voltage
VCOMP_OP COMP pin open
COMP Open-loop Protection Delay
Cycles
TOLP
RT = 100kΩ
Short Circuit Current
IZER O
VCOMP = 0V
Current-Sense Section
Initial Peak Current Limit Offset
Leading Edge Blanking Time
Propagation Delay Time
GATE Section
VCSTH
TLEB
TPD
Rising Time
Falling Time
Gate Output Clamping Voltage
Over Temperature Protection
TR
TF
VCL AM P
TOTP
VDD = 15V, CL = 1nF
VDD = 15V, CL = 1nF
VDD = 22V
OTP Hysteresis
TOTP _H YS
Min Typ Max Unit
-- ±6 -- %
-- 4 -- ms
70 75 80 %
-- -- 2 %
-- -- 5 %
5.2 5.6
6
V
-- 60 -- ms
-- 1.2 2.2 mA
0.8 0.85 0.9
-- 420 520
-- 100 --
V
ns
ns
-- 250 350
-- 150 250
-- 12 --
140 --
--
-- 30 --
ns
ns
V
°C
°C
Note 1. Stresses beyond those listed under “ Absolute Maximum Ratings” may cause permanent damage to the device.
These are stress ratings only, and functional operation of the device at these or any other conditions beyond those
indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
Note 2. θJA is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity test board of
JEDEC 51-3 thermal measurement standard.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
Note 5. Guaranteed by design.
R7731A-07 Mar 2010
5
5 Page 
#It's highly recommended to add a resistor in parallel
with the opto-coupler. To provide sufficient bias current
to make TL-431 regulate properly, 1.2kΩ resistor is
suggested.
Brownout Protection : During heavy load, this will
trigger 60ms protection and shut down the system. If
it's in light load condition, system will be shut down
after VDD is running low and triggers UVLO.
OVP : Output voltage can be roughly sensed by VDD
pin.If the sensed voltage reaches 27V threshold, system
will be shut down after 20us deglitch delay.
Feedback Open and Opto-Coupler Short : This will
trigger OVP or 60ms delay protection. It depends on
which one occurs first.
OTP : Internal OTP function will protect the controller
itself from suffering thermal stress and permanent
damage. It stops the system from switching until the
temperature is under threshold level. Meanwhile, if VDD
reaches VDD turn off threshold voltage, system will
hiccup till over temperature condition is gone.
R7731A
R7731A-07 Mar 2010
11
11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet R7731A.PDF ] | |
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