OPERATION
GS 15, 12 BITS
194 BITS
GS 0, 12 BITS
LT3745
C1
C0
GS
FRAME
DC 15, 6 BITS
x
x
x
x
x
x
DC 0, 6 BITS
x
x
x
x
x
x
C1
C0
DC
FRAME
DC 15, 6 BITS
0
0
0
0
0 S15
COMMAND REGISTER:
C1: ENABLE LED CHANNELS - ENABLE = 1, DISABLE = 0
C0: FRAME SELECT - GS FRAME = 0, DC FRAME = 1
DC 0, 6 BITS
0
0
0
0
0
STATUS REGISTER:
S0-S15: LED 0-15 FAULT - FAULT = 1, OK = 0
F0:
OT - OVER TEMPERATURE = 1, OK = 0
S0 0
F0
STATUS
FRAME
3745 F02
Figure 2. Serial Data Frame Format
LDI
SCKI
SDI
tWH-CKI
1
tWL-CKI
DC 15
MSB
SR[0]
DC 15
MSB
SR[1]
186
tSU-SDI
tHD-SDI
DC 0
LSB
DC 0
LSB
DC 0
LSB + 1
LDO
SCKO
1
186
SDO/
SR[385]
tSU-LDI tWH-LDI tHD-LDI
193
194
1
192
193
194
1
C1
C0 = 1
GS 15
MSB
GS 0
LSB
C1
C0 = 0
GS 15
MSB
C1
C0 = 1
F0
GS 15
MSB
GS 0
LSB
C1
C0 = 0
F0
GS 15
MSB
x
C1
0
F0
tPD-LD↓
tPD-LD↑
GS 0
GS 0
LSB + 1
LSB
C1
0
F0
tPD-SCK↑
193
194
tPD-SCK↓
tPD-SD
DC 15
MSB
INPUT DATA
1
192
193
194
DC 15
MSB
DC 15
MSB – 1
STATUS DATA
0
F0
GS 15
MSB
DC 15
MSB
3746 F03
Figure 3. Serial Data Input and Output Timing Chart
3745f
15