Microsemi Corporation LX1686CPW Datasheet

RangeMAX

)

D IGITAL DIMMING CCFL CONTROLLER IC

TM

LX1686

T HE I NFINITE P OWER OF I NNOVATION

DESCRIPTION KEY FEATURES

The LX1686 Backlight Controller IC

provides all the control functions needed
to implement Linfinity’s direct drive in­verters used to operate cold cathode fluo­rescent lamps (CCFL’s). This IC can be
used to control single or multiple-lamp
configurations. CCFL’s are used for back
or edge lighting of liquid crystal flat panel
displays (LCD’s) and typically find appli­cation in notebook computers, web
browsers, automotive and industrial in­strumentation, and entertainment sys­tems.

The LX1686 includes a PWM con-

trolled lamp current burst circuit that

can provide a >100:1 dimming range from
a simple zero to 2.5V potentiometer in­put. The PWM dimming burst rate is
easily synchronized to the LCD panel’s
frame rate to prevent interference from
optical beat frequencies.

NOTE: For current data & package dimensions, visit our web site: http://www.linfinity.com.

Safety and reliability features in-

clude a new dual feedback contol loop

that permits regulation of maximum lamp
strike voltage as well as lamp current.
Regulating maximum lamp voltage per­mits the designer to provide for ample
worst case lamp strike voltage while at
the same time conservatively limit maxi­mum open circuit voltage.

An innovative new strike voltage

generation technique enables the mod-

ule designer to optimize high voltage
transformer design for maximum oper­ating efficiency with no power dissipat­ing overhead to guarantee strike capa­bility.

Direct drive topology is a non-reso­nant, oscillator-controlled PWM regu­lation method. The LX1686 allows a

wide choice of fixed operating frequen­cies to match lamp current frequency to
the lamp’s most efficient operating point,
and to minimize high frequency interfer­ence.

P RELIMINARY DATA SHEET

■ RangeMAX

■ Synchronizable To Display Video Frequency

■ High Voltage Feedback Loop Directly

Controls Maximum Open Lamp And
Minimum Strike Voltages

■ Transformer Protected From Over-Heating

During Lamp Striking

■ Micro-Amp Sleep Mode

■ User-Programmable Fixed Frequency

Operation

■ Under-Voltage Lockout Feature With Power-

Up Reset

■ Built-In Soft-Start Feature

■ Operates With 3.3V or 5V Power Supplies

■ 100mA Output Drive Capability

■ Notebooks

■ Instrumentation Displays

■ Desktop Computer Monitors

■ Low Ambient Light Displays (used in

Aircraft, Automobiles, and Hand-held
Equipment)

■ Extemely High Efficiency From 3.3V or 5V

Power Supplies

■ Lower Cost Than Conventional Buck / Royer

Inverter Topologies

■ Improved Lamp Strike Capability

■ Improved Over-Voltage Control

TM

Wide Range Dimming (>100:1)

APPLICATIONS

BENEFITS

Power Used (Watts)

Copyright © 2000
Rev. 0.4 1/00

RANGEMAX VS. ANALOG DIMMING

5

4

3

2

1

0

30 45

Standard Analog
Dimming Inverter

60

75 90 105

Light Output (Nits

Note: All surface-mount packages are available in Tape & Reel.

LinFinity's
RangeMAX

Append the letter "T" to part number. (i.e. LX1686CPWT)

L INF INITY MICROELECTRONICS INC.

11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841, 714-898-8121, FAX: [phone]

PRODUCT HIGHLIGHT

Light emitted by a CCFL is proportional to the current
flowing through it. There are two ways to control the
current: by adjusting the amplitude of a continuous AC
current; or, as with RangeMAX technology, by varying
the amount of time a burst of full current is present.
RangeMAX technology frees the backlight inverter
module designer to operate in a lower brightness and
lower power consumption mode than is possible with
conventional amplitude control methods.

PACKAGE ORDER INFO

T

(°C)

A

0 to 85 LX1686CPW

Plastic TSSOP

PW

24-pin

1

PRODUCT DATABOOK 1996/1997

LX1686

D IGITAL DIMMING CCFL CONTROLLER IC

P RELIMINARY DATA SHEET

ABSOLUTE MAXIMUM RATINGS (Note 1)

Supply Voltage (VDD, VDD_P) ......................................................................... 6.5V

Digital Inputs .................................................................................. -0.3 to VDD+0.5V

Analog Inputs .................................................................................. -0.3 to VDD+0.5V

Digital Outputs ................................................................................ -0.3 to VDD+0.5V

Analog Outputs ............................................................................... -0.3 to VDD+0.5V

Operating Junction Temperature

Plastic (DB, PW Packages) .......................................................................... 150°C

Storage Temperature Range .............................................................. -65°C to 150°C

Lead Temperature (Soldering, 10 seconds) .................................................... 300°C

Note 1. Exceeding these ratings could cause damage to the device. All voltages are with

PW PACKAGE:

Junction Temperature Calculation: TJ = TA + (P
The θ
system. All of the above assume no ambient airflow.

respect to Ground. Currents are positive into, negative out of the specified
terminal.

THERMAL DATA

D

x θ

θθ

θ

θθ

JA

).

JA

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

numbers are guidelines for the thermal performance of the device/pc-board

JA

100°C/W

RangeMAX

PACKAGE PIN OUTS

AOUT

VSS_P

VSS

AFD_C

RAMP_C

RAMP_R

FVERT

PD_CR

VCO_C

BRT_POS

BRITE

DIG_DIM

1 24

223

322

421

520

619

718

817

916

10 15

11 14

12 13

PW PACKAGE

(Top View)

TM

BOUT
VDD_P
VDD
TRI_C
OLSNS
ISNS
ICOMP
VSNS
VCOMP
BRT
I_R
ENABLE

ELECTRICAL CHARACTERISTICS

(Unless otherwise specified, these specifications apply over the recommended operating conditions of TA = 0 to 85°C, VDD=VDD_P= 3.0 to 5.5V)
(Ri = 40kΩ, C

Power Supply Voltage VDD VDD = VDD_P
Operating Current I
Power Supply Voltage VDD_P VDD = VDD_P
Output Buffer Operating Current I
UVLO Threshold V
UVLO Hysteresis V

= 0.01µF, C

VCO

= 0.22µF, C

AFD

Parameter

= 0.83µF, C

TRI

= 208pF, R

RAMP

Symbol

DD

DD_P

TH_UVLO

H_UVLO

= 15kΩ, C

RAMP

= 0.22µF, C

PD

= 0.047µF, R

PDC

Test Conditions Units

VDD = VDD_P = 5V

Volsns = VDD = VDD_P = 5V, CA = CB = 1000pF

= 110kΩ.)

PD

LX1686

Min. Typ. Max.

35.5V
57mA

35.5V
210mA

2.7 2.9 V
160 mV

Direct Drive Ramp Block

Triangular Wave Generator Analog Output Peak Voltage V
Triangular Wave Generator Analog Output Valley Voltage
Triangular Wave Generator Oscillation Frequency F
Triangular Wave Generator Oscillation Charge Current I
Triangular Wave Generator Oscillation Discharge Current

I

DISCHG_TRI

Ramp Generator Analog Output Peak Voltage V
Ramp Generator Analog Output Valley Voltage V
Ramp Frequency Change Threshold V

Ramp Generator Oscillation Frequency - Nominal F
Ramp Generator Oscillation Frequency - Maximum F
OLSNS Threshold Voltage V
OLSNS Hysteresis V
OLSNS-to-ICOMP Propagation Delay T

P_TRI

V

V_TRI

_TRI

CHG_TRI

Tri_c = 0V
Tri_c = 3V

P_RAMP

V_RAMP

TH_RAMP_R

VDD = 3V
VDD = 5.5V

RAMPVTRI_C

RAMP_HIVTRI_C

TH_OLSNS

H_OLSNS

D_OLSNS

VDD = 3V
VDD = 3V
GBD

= 1.4V
= 2.25V

-2.3 -2.55 -2.9 µA

1.55 1.65 1.8 V

170 200 256 KHz
250 300 360 mV

2.25 V

0.75 V
10 Hz

2.3 2.65 2.9 µA

2.25 V

0.75 V

1.4 1.5 1.65 V

84 100 116 KHz

45 mV

1µS

2

Copyright © 2000

Rev. 0.4 1/00