tb62778fng Marktech Optoelectronics, tb62778fng Datasheet - Page 14

• Manufacturer Part Number: tb62778fng
• Description: 8-channel Constant-current Led Driver Of The 3.3-v And 5-v Power Supply Voltage Operation
• Manufacturer: Marktech Optoelectronics

Special Mode
total brightness adjustment mode and error detection (OOD/OSD) mode.
normal mode.
Sequence for Switching to Special Mode
Only the above signal sequence puts the TB62778FNG in special mode. In this mode, two sub-modes are available:
While switching to special mode, data is not latched by LATCH . After power-on, the TB62778FNG defaults to
Total Brightness Adjustment Mode
into the brightness adjustment register instead of the output latches. Once latched into the brightness adjustment
register, the brightness code is held until the TB62778FNG is powered off or it is overwritten with a new code.
Writing a brightness code
In total brightness adjustment mode, when LATCH is High, a brightness code in the shift register is latched
Adjusting the total brightness
determine the voltage applied to the R-EXT terminal (VG). Bit 1, HC, divides the voltage range into 25% to
50% (HC = 0) or 50% to 100% (HC = 1), and bits 2 to 7 are used to adjust the voltage in 64 steps within the
range selected by bit 1. After on power, total brightness adjustment code becomes the above-mentioned default
value.
Bit definition of the brightness code
Default
The 8-bit brightness code is shifted in from the SERIAL-IN terminal, with bit 7 first. Bits 1 to 7 of the code
SERIAL-IN
ENABLE
ENABLE
LATCH
LATCH
CLOCK
CLOCK
Reserved
Bit 0
1
L
H
H
1
L
Bit 7
0
2
L
L
Bit 1
HC
1
Bit 6
H
3
L
1
H
H
4
Bit 5
2
H
5
L
Bit 2
AG5
Brightness code
1
Bit 4 Bit 3
3
TENTATIVE
4
Bit 3
AG4
14
1
Bit 2
5
Bit 1
6
Bit 4
AG3
1
Bit 0
7
H
Bit 5
AG2
1
Bit 6
AG1
1
(Ver.0.0) 08-02-07
TB62778FNG
Bit 7
AG0
1