AS3677 datasheet(19/68 Pages) AMSCO

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AS3677

Datasheet - D e ta i l e d D e s c r i p t i o n

8.4

Current Sinks

The AS3677 contains three general purpose current sinks intended to control backlight LEDs.

CURR1, CURR2 and CURR6 are used as feedback for the Step Up DC/DC Converter (regulated to 0.5V in this config-

uration) see Feedback Selection on page 11.

The processing inside the AS3677 is shown in Figure 15 (shown for one current source only):

Table 18. Curr low voltage status2

Addr: 2Bh

Curr low voltage status2

Indicates the low voltage status of the current sinks. If the currX_low_v bit is

set, the voltage on the current sink is too low, to drive the selected output

current

Bit

Bit Name

Default Access

Description

curr1_low_v

voltage of current Sink CURR1 >currhv_switch

voltage of current Sink CURR1 <currhv_switch

curr2_low_v

voltage of current Sink CURR2 >currhv_switch

voltage of current Sink CURR2 <currhv_switch

Table 19. Current Sink Function Overview

Current Sink

Max.

Voltage (V)

Max.

Current

(mA)

Resolution

Software Current

Control

Hardware On/Off

Control

(Bits)

(mA)

RGB1

5.5

25.5

0.1

Separate

Internal PWM; external

PWM at DLS1, Pattern

generator

RGB2

RGB3

CURR1

26.0

25.5

0.1

Separate

Internal PWM; external

PWM at DLS1, Pattern

generator

CURR2

Internal PWM; external

PWM at DLS1 or

DLS2, Pattern

generator

CURR6

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