DM631B Datasheet, PDF (15/31 Pages) Silicon Touch Technology Inc. – Maximum output voltage: 17V

點晶科技股份有限公司
SILICON TOUCH TECHNOLOGY INC.
新竹市科學園區展業一路 9 號 7 樓之 1
9-7F-1, Prosperity RoadⅠ, Hsin-Chu, Taiwan, R.O.C.
Tel：886-3-5645656 Fax：886-3-5645626
DM631B
Internal/External Clock Mode selection
Grayscale luminous of each channel comes from comparisons of grayscale PWM luminous
data and grayscale counter value. In internal-clock mode, DM631B provides build-in oscillator for
counter operation. In external-clock mode, the clock source of counter is from control system
through GCK pin. The default mode is the Internal-Clock Mode(ICM^＊1) after power-on. Users
could do mode select between ICM and External-Clock Mode (ECM^∗2 ) by following timing
sequence. The option 1 shows four rising edges of latch pulses ( LAT ) when the data clock (DCK)
kept at high level and the grayscale clock (GCK) kept at low then sending three rising edges of DCK
when LAT and GCK both kept at high level. Then we can input external gray scale clock from
GCK pin to operate grayscale PWM function after the falling edge of LAT . The option 2 shows
five rising edges of LAT when DCK kept at high level and GCK at low level then sending four
rising edges of DCK , while LAT and GCK kept at high level . After the falling edge of LAT ,
grayscale PWM function operates by internal gray scale clock generator. Notice that when internal
RESET at low level, all the shift registers in DM631B will be cleared (Kept at Low level).
DCK
1 23
DCK
1 234
GCK
X
X
GCK X
X
LAT
1234
LAT
1 2345
RESET
(internal)
Option1 :
t
Signals Combination to set up
External-Clock Mode (ECM)
RESET
(internal)
t
Option 2 : Signals Combination to set up
Internal-Clock Mode (ICM)
LED Open Detection
DM631B provides a real time monitor of LED open detection function without extra
components or circuit design. It will be identified as a LED open failure when the output is turned
on but the output voltage is below 0.2V. The test result of each channel will write to its
correspondent shift register which is in LSB position (ERR[11], ERR[10], …., ERR[0]) while strobe
signal is active. User can refer to timing diagram on page11. Detecting report could be retrieved
from serial-out (DAO) data. If the system reads ‘1’ back, that indicates LED is in normal status. But
if ‘0’ was retrieved then LED open failure has occurred. In order to make sure LED open detection
function is in well operating condition, thold(L)^*3 should larger then 360n sec(typ) due to the
build-in delay between outputs. And it is recommended that all the luminance data wrote to ‘1’
during detection.
＊_{1 ICM switch to ECM timing diagram, please refer to page 20.}
∗ _{2 ECM switch to ICM timing diagram, please refer to page 21}
* _{3 Hold time between LAT and DCK, please refer to page 15.}
16-channel 12-bit PWM Constant Current LED Driver Version:PRE.001 Preliminary
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