Richtek RT8465ZS Schematic [ru]

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Richtek RT8465ZS Schematic

®

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

 

 

 

 

 

 

+

 

 

 

 

L

 

AC IN

~

 

 

 

 

 

D1

-

D2

 

 

 

 

 

 

 

 

RT8465

 

 

 

 

 

 

 

 

 

 

 

 

 

VCC

 

 

 

 

 

R1

 

 

 

 

R2

 

 

 

 

 

 

SIN

GATE

M1

 

 

 

C2

 

 

 

 

C1

 

 

 

 

 

 

ICOMP

FB

 

 

 

 

C3

 

 

VCOMP

 

 

 

 

 

R4

R5

 

 

R3

 

 

 

 

 

 

 

 

 

 

C4

C5

SENSE

GND

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RS

Copyright ©2013 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS8465-01 March 2013

www.richtek.com

 

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

 

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

ZSYMDNN

 

 

 

Pin No.

Pin Name

Pin Function

 

1

GND

Ground.

 

2

GATE

Gate Driver for External MOSFET Switch.

 

 

 

 

3

VCC

Power Supply. For good bypass, place a ceramic capacitor near the VCC pin.

 

 

Inductor Current Sense Input. The inductor current is sensed by a resistor between

4

SENSE

GND and SENSE pins. The sense pin signal is used as the saw tooth signal to the

PWM comparator. The comparator output will modulate the GATE turn-on duty to

 

 

 

 

achieve the output voltage regulation.

 

 

 

Output Voltage Sense Input. The Output voltage is sensed through an external

5

FB

resistive divider. The sensed voltage (which is tied to amplifier negative input) is

compared to an internal reference threshold at 1.2V (which is tied to amplifier

 

 

 

 

positive input).

 

 

 

Output of the Multiplier. To achieve high power factor, the voltage loop amplifier

6

ICOMP

output signal is modulated with the sensed input voltage through the SIN pin by an

 

 

internal multiplier. A compensation network between ICOMP and GND is needed.

7

SIN

Input Power Voltage Sensing for PFC Function. An external resistor

for input

voltage sensing is connected to the power input.

 

 

 

 

8

VCOMP

Output of the Internal Voltage Loop GM Amplifier. A compensation

network

between VCOMP and GND is needed.

 

 

 

 

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

 

+

Chip

 

 

 

+

-

Enable

 

 

 

VCC

10V/8V

 

 

 

8V

 

 

 

 

 

OVP

OSC

S

Q

GATE

35V

+

 

R

 

200k

-

 

 

PWM

R

 

 

GND

 

 

 

 

Control

 

 

SENSE

 

 

Circuit

 

 

 

ICOMP

 

 

 

 

 

VCOMP

 

PFC

 

 

 

1.2V

+

 

 

SIN

Control

 

 

FB

 

 

-

Circuit

 

 

 

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

 

SOP-8 ------------------------------------------------------------------------------------------------------------------------

0.53W

z Package Thermal Resistance (Note 2)

 

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)

 

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

 

Test Conditions

Min

 

Typ

Max

Unit

 

 

 

 

 

 

 

 

 

Input Start-Up Voltage

VST

 

 

--

 

10

11

V

Under Voltage Lockout Threshold

VUVLO

 

 

7

 

8

--

V

Under Voltage Lockout Threshold

VUVLO

 

 

--

 

2

--

V

Hysteresis

 

 

 

Input Supply Current

ICC

 

After Start-Up, VCC = 24V

--

 

2

5

mA

Input Quiescent Current

IQC

 

Before Start-Up, VCC = 7V

--

 

0.1

--

μA

Oscillator

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Switching Frequency

fSW

 

VSIN = 14V

190

 

220

250

kHz

Maximum Duty in Transient

DMAX(TR)

 

VC = 3V

--

 

--

100

%

Operation

 

 

Maximum Duty in Steady State

DMAX

 

 

--

 

97

--

%

Operation

 

 

 

 

 

 

 

 

 

 

 

Blanking Time

tBLANK

 

 

200

 

--

--

ns

Minimum Turn-Off Time

 

 

(Note 5)

--

 

650

--

ns

 

 

 

 

 

 

 

 

 

Current Sense Amplifier

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current Sense Voltage

VSENSE

 

VCOMP = 1V, SIN = 15V

--

 

−100

--

mV

Sense Input Current

ISENSE

 

Sense = 100mV (Note 5)

--

 

10

--

μA

 

 

 

 

 

 

 

 

 

Copyright ©2013 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

 

 

 

 

DS8465-01 March 2013

4

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