Richtek RT8465ZS Schematic [ru]
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RT8465
Constant Voltage High Power Factor PWM Boost Driver Controller for MR16 Application
General Description
The RT8465 is a constant output voltage, active high power factor, PWM Boost driver controller. It can be used as the first Boost stage followed by a constant current Buck converter with input from AC/electronic transformer in MR16/AR111 application. To achieve high power factor, the AC input voltage from AC/electronic transformer is sensed via the SIN pin. An internal power factor correction circuit follows the sensed sine waveform and modulates the external MOSFET duty cycle-by-cycle to achieve constant output voltage.
The output voltage is adjustable via an output resistive divider. By operating at 220kHz, the filter component size can be small to fit in tight MR16 space. To drive industrial grade MOSFET switches, the RT8465 gate driver can deliver up to 0.8A output current with 9V gate output voltage.
Features
zWide Input Voltage Range : 8V to 32V
zHigh Power Factor Correction with Simple System Circuits
zAdjustable Constant Output Voltage
zBuilt-in High Power Factor Correction Circuit
zTypical 250μA Start-Up Supply Current
zLow Quiescent Current : 0.1μA
zSOP-8 Package
zRoHS Compliant and Halogen Free
Applications
zMR16, AR111 Lamps
zPFC Controller
Simplified Application Circuit |
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AC IN |
~ |
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D1 |
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D2 |
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RT8465 |
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VCC |
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R1 |
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R2 |
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SIN |
GATE |
M1 |
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C2 |
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C1 |
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ICOMP |
FB |
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C3 |
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VCOMP |
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R4 |
R5 |
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R3 |
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C4 |
C5 |
SENSE |
GND |
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RS |
Copyright ©2013 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
DS8465-01 March 2013 |
www.richtek.com |
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1 |
RT8465
Ordering Information
RT8465 
Package Type
S : SOP-8
Lead Plating System
Z : ECO (Ecological Element with Halogen Free and Pb free)
Note :
Richtek products are :
`RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.
`Suitable for use in SnPb or Pb-free soldering processes.
Functional Pin Description
Pin Configurations
(TOP VIEW)
GND |
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8 |
VCOMP |
GATE |
2 |
7 |
SIN |
VCC |
3 |
6 |
ICOMP |
SENSE |
4 |
5 |
FB |
SOP-8
Marking Information
RT8465 |
RT8465ZS : Product Number |
YMDNN : Date Code |
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ZSYMDNN |
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Pin No. |
Pin Name |
Pin Function |
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1 |
GND |
Ground. |
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2 |
GATE |
Gate Driver for External MOSFET Switch. |
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3 |
VCC |
Power Supply. For good bypass, place a ceramic capacitor near the VCC pin. |
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Inductor Current Sense Input. The inductor current is sensed by a resistor between |
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4 |
SENSE |
GND and SENSE pins. The sense pin signal is used as the saw tooth signal to the |
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PWM comparator. The comparator output will modulate the GATE turn-on duty to |
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achieve the output voltage regulation. |
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Output Voltage Sense Input. The Output voltage is sensed through an external |
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5 |
FB |
resistive divider. The sensed voltage (which is tied to amplifier negative input) is |
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compared to an internal reference threshold at 1.2V (which is tied to amplifier |
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positive input). |
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Output of the Multiplier. To achieve high power factor, the voltage loop amplifier |
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6 |
ICOMP |
output signal is modulated with the sensed input voltage through the SIN pin by an |
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internal multiplier. A compensation network between ICOMP and GND is needed. |
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7 |
SIN |
Input Power Voltage Sensing for PFC Function. An external resistor |
for input |
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voltage sensing is connected to the power input. |
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8 |
VCOMP |
Output of the Internal Voltage Loop GM Amplifier. A compensation |
network |
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between VCOMP and GND is needed. |
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Copyright ©2013 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
www.richtek.com |
DS8465-01 March 2013 |
2
RT8465
Function Block Diagram
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Chip |
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Enable |
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VCC |
10V/8V |
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8V |
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OVP |
OSC |
S |
Q |
GATE |
35V |
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R |
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200k |
- |
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PWM |
R |
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GND |
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Control |
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SENSE |
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Circuit |
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ICOMP |
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VCOMP |
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PFC |
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1.2V |
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SIN |
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Control |
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FB |
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Circuit |
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Operation
The RT8465 is a floating-GND Boost PWM current mode controller with an integrated low side floating gate driver. The start up voltage of RT8465 is around 10V. Once VCC is above 10V, the RT8465 will maintain operation until VCC drops below 8V.
The RT8465's main control loop consists of a 220kHz fixed frequency oscillator, an internal 1.2V feedback (FB) voltage sense threshold, and the PFC control circuit with a PWM comparator. In normal operation, the GATE turns high when the gate driver is set by the oscillator (OSC). When the feedback (FB) voltage is below the reference
1.2V threshold, the VCOMP pin voltage will go high. The ICOMP signal is the result of VCOMP signal multiplied with SINsignal. Higher ICOMP voltage means longerGATE turn-on period. The GATE does not always turn off in each cycle. The GATE will be turned on again by OSC for the next switching cycle.
The RT8465 provides several protections, including input voltage Under Voltage Lockout (UVLO), Over Current Protection (OCP) and VCC Over Voltage Protection (OVP). Additionally, to ensure the system reliability, the RT8465 is built with internal thermal protection function.
Copyright ©2013 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
DS8465-01 March 2013 |
www.richtek.com |
3
RT8465
Absolute Maximum Ratings (Note 1)
z VCC, SIN to GND ---------------------------------------------------------------------------------------------------------- |
−0.3V to 40V |
z GATE to GND (Note 6) ------------------------------------------------------------------------------------------------- |
−0.3V to 16V |
z VCOMP, ICMOP to GND ------------------------------------------------------------------------------------------------ |
−0.3V to 4V |
z FB to GND ------------------------------------------------------------------------------------------------------------------ |
−0.3V to 2V |
z SENSE to GND ------------------------------------------------------------------------------------------------------------ |
−1V to 0.3V |
z Power Dissipation, PD @ TA = 25°C |
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SOP-8 ------------------------------------------------------------------------------------------------------------------------ |
0.53W |
z Package Thermal Resistance (Note 2) |
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SOP-8, θJA ------------------------------------------------------------------------------------------------------------------ |
188°C/W |
z Junction Temperature ----------------------------------------------------------------------------------------------------- |
150°C |
z Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------- |
260°C |
z Storage Temperature Range -------------------------------------------------------------------------------------------- |
−65°C to 150°C |
z ESD Susceptibility (Note 3) |
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HBM (Human Body Model) ---------------------------------------------------------------------------------------------- |
2kV |
MM (Machine Model) ----------------------------------------------------------------------------------------------------- |
200V |
Recommended Operating Conditions |
(Note 4) |
z Supply Input Voltage, VCC ---------------------------------------------------------------------------------------------- |
8V to 32V |
z Junction Temperature Range -------------------------------------------------------------------------------------------- |
−40°C to 125°C |
z Ambient Temperature Range -------------------------------------------------------------------------------------------- |
−40°C to 85°C |
Electrical Characteristics
(VCC = 24VDC, CLOAD = 1nF, RLOAD = 2.2Ω in series, TA = 25°C, unless otherwise specified)
Parameter |
Symbol |
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Test Conditions |
Min |
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Typ |
Max |
Unit |
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Input Start-Up Voltage |
VST |
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-- |
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10 |
11 |
V |
Under Voltage Lockout Threshold |
VUVLO |
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7 |
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8 |
-- |
V |
Under Voltage Lockout Threshold |
VUVLO |
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-- |
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2 |
-- |
V |
Hysteresis |
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Input Supply Current |
ICC |
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After Start-Up, VCC = 24V |
-- |
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2 |
5 |
mA |
Input Quiescent Current |
IQC |
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Before Start-Up, VCC = 7V |
-- |
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0.1 |
-- |
μA |
Oscillator |
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Switching Frequency |
fSW |
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VSIN = 14V |
190 |
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220 |
250 |
kHz |
Maximum Duty in Transient |
DMAX(TR) |
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VC = 3V |
-- |
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-- |
100 |
% |
Operation |
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Maximum Duty in Steady State |
DMAX |
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-- |
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97 |
-- |
% |
Operation |
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Blanking Time |
tBLANK |
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200 |
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-- |
-- |
ns |
Minimum Turn-Off Time |
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(Note 5) |
-- |
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650 |
-- |
ns |
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Current Sense Amplifier |
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Current Sense Voltage |
VSENSE |
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VCOMP = 1V, SIN = 15V |
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−100 |
-- |
mV |
Sense Input Current |
ISENSE |
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Sense = 100mV (Note 5) |
-- |
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10 |
-- |
μA |
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Copyright ©2013 Richtek Technology Corporation. All rights reserved. |
is a registered trademark of Richtek Technology Corporation. |
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www.richtek.com |
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DS8465-01 March 2013 |
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