Richtek RT8465ZS Schematic [ru]

RT8465

Constant Voltage High Power Factor PWM 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

z Wide Input Voltage Range : 8V to 32V

z High Power Factor Correction with Simple System

Circuits

z Adjustable Consta nt Output Voltage

z Built-in High Power Factor Correction Circuit

z T ypical 250

z Low Quiescent Current : 0.1

z SOP-8 Package

z RoHS Compliant and Halogen Free

μμ

μA Start-Up Supply Current

μμ

Applications

z MR16, AR111 Lamps

z PFC Controller

Boost Driver

μμ

μA

μμ

Simplified Application Circuit

AC IN

+ ~

VCC

SIN

VCOMP

RT8465

GNDSENSE

GATE

FBICOMP

DS8465-01 March 2013 www.richtek.com

RT8465

Ordering Information

Pin Configurations

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 require-

ments of IPC/JEDEC J-STD-020.

` Suitable for use in SnPb or Pb-free soldering processes.

Marking Information

RT8465 ZSYMDNN

Functional Pin Description

Pin No. Pin Name Pin Function

1 GND Ground.

2 GATE Gate Driver for External MOSFET Switc h.

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

5 FB

6 ICOMP

7 SIN

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 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 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.

Input Power Voltage Sensing for PFC Function. An external resistor for input voltage sensing is connected to the power input.

(TOP VIEW)

GND

GATE

VCC

SENSE

SOP-8

RT8465ZS : Product Number

YMDNN : Date Code

VCOMP

SIN

ICOMP

8 VCOMP

Output of the Internal Voltage Loop GM Amplifier. A compensation network between VCOMP and GND is needed.

DS8465-01 March 2013www.richtek.com

Function Block Diagram

RT8465

VCC

35V

GND

ICOMP

VCOMP

1.2V

10V/8V

OVP

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

Chip

Enable

OSC

PWM

Control

Circuit

PFC

Control

Circuit

S Q

200k

GATE

SENSE

SIN

1.2V threshold, the VCOMP pin voltage will go high. The

ICOMP signal is the result of VCOMP signal multiplied

with SIN signal. Higher ICOMP voltage means longer GATE

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.

DS8465-01 March 2013 www.richtek.com

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, P

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

@ T

= 25°C

Recommended Operating Conditions

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

(Note 4)

Electrical Characteristics

(VCC = 24VDC, C

Input Start-Up Voltage VST -- 10 11 V

Under Voltage Lockout Threshold V

Under Voltage Lockout Threshold 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 V

Maximum Duty in Transient Operation

Maximum Duty in Steady State Oper ation

LOAD

= 1nF, R

= 2.2Ω in series, TA = 25°C, unless otherwise specified)

LOAD

Parameter Symbol Test Conditions Min Typ Max Unit

7 8 -- V

UVLO

ΔV

-- 2 -- V

UVLO

= 14V 190 220 250 kHz

SIN

MAX(TR)

MAX

VC = 3V -- -- 100 %

-- 97 -- %

Blanking Time t

200 -- -- ns

BLANK

Minimum Turn-Off Time (Note 5) -- 650 -- ns

Current Sense Amplifier

Current Sense Voltage V

Sense Input Current I

SENSE

= 1V, SIN = 15V -- −100 -- mV

COMP

Sense = 100mV (Note 5) -- 10 -- μA

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Richtek RT8465ZS Schematic [ru]

Specifications and Main Features

Frequently Asked Questions

User Manual