MAX8709B Просмотр технического описания (PDF) - Maxim Integrated

Номер в каталоге

Компоненты Описание

производитель

MAX8709B

High-Efficiency CCFL Backlight Controller with SMBus Interface

Maxim Integrated 

High-Efficiency CCFL Backlight

Controller with SMBus Interface

Table 4. SHMD Register Bit Descriptions

BIT NAME POR

STATE

DESCRIPTION

2 SHMD2

0

SHMD2 = 1 forces the lamp off and sets STATUS1. SHMD2 = 0 allows the lamp to operate,

although it may still be shut down by SUS (depending on the state of SHMD1 and SHMD0).

1 SHMD1

0

When SUS = 0, this bit has no effect. SUS = 1 and SHMD1 = 1 forces the lamp off and sets STATUS1.

SUS = 1 and SHMD1 = 0 allows the lamp to operate, although it may still be shut down by the SHMD2 bit.

0 SHMD0

1

When SUS = 1, this bit has no effect. SUS = 0 and SHMD0 = 1 forces the lamp off and sets STATUS1.

SUS = 0 and SHMD0 = 0 allows the lamp to operate, although it may still be shut down by the SHMD2 bit.

Brightness Register [BRIGHT4 – BRIGHT0]

(POR = 0b10111)

The 5-bit brightness register corresponds to the 5-bit

brightness code used in dimming control (See the

Dimming Control section). BRIGHT4 - BRIGHT0 =

0b11111 sets minimum brightness and BRIGHT4 -

BRIGHT0 = 0b00000 sets maximum brightness. Note that

the brightness-register polarity of command bytes 0xA9

and 0xAA are inverted from that of command byte 0x01.

Shutdown-Mode Register [SHMD2–SHMD0]

(POR = 0b001)

The 3-bit shutdown-mode register configures the oper-

ation of the device when the SUS pin is toggled as

described in Table 4. The shutdown-mode register can

also be used to directly shut off the CCFL regardless of

the state of SUS (Table 5).

Table 5. SUS and SHMD Register Truth

Table

SUS

0

0

1

1

X

SHMD2 SHMD1 SHMD0 OPERATING MODE

0

X

0 Operate

0

X

1 Shutdown, STATUS1 set

0

0

X Operate

0

1

X Shutdown, STATUS1 set

1

X

X Shutdown, STATUS1 set

Status Register [STATUS1–STATUS0]

(POR = 0b11)

The status register returns information on fault condi-

tions. If the MAX8709B detects that VIFB does not

exceed 30% of VLOT continuously for 1.22s, the IC

latches STATUS1 to zero. STATUS1 is reset to 1 by tog-

gling SUS or by toggling the input power.

STATUS0 reports 1 as long as no overcurrent condi-

tions are detected. If an overcurrent condition is detect-

ed in any given DPWM period, STATUS0 is cleared for

the duration of the following DPWM period. If an over-

current condition is not detected in any given DPWM

period, STATUS0 is set for the duration of the following

DPWM period. Note that the status-register polarity of

command bytes 0xA9 and 0xAA are inverted from that

of command byte 0x02.

ID Registers

The ID registers return information on the manufacturer

chip ID and the chip revision number. The MAX8709B is

the first-generation advanced CCFL controller and its

ChipRev is 0x00. Reading from MfgID register returns

0x4D, which is the ASCII code for M (for Maxim). The

ChipID register returns 0x0D. Writing to these registers

has no effect.

Table 6. Status-Register Bit Descriptions (Read Only, Writes Have No Effect)

BIT

NAME

POR

STATE

DESCRIPTION

1 STATUS1

STATUS1 = 0 (or STATUS1 = 1) means that a lamp-out condition has been detected. The

1

STATUS1 bit stays clear even after the lamp-out condition has gone away. The only way to set

STATUS1 is to shut off the lamp by programming the shutdown-mode register or by toggling SUS.

0 STATUS0

STATUS0 = 0 (or STATUS0 = 1) means that an overcurrent condition was detected during the

1

previous DPWM period. STATUS0 = 1 means that an overcurrent condition was not detected

during the previous DPWM period.

______________________________________________________________________________________ 19

Share Link: