isl97635 Intersil Corporation, isl97635 Datasheet - Page 19

• Manufacturer Part Number: isl97635
• Description: Smbus 8-channel Led Driver
• Manufacturer: Intersil Corporation

PWM Brightness Control Register (0x00)
The Brightness control resolution has 256 steps of PWM duty
cycle adjustment. The bit assignment is shown in Figure 23. All
of the bits in this Brightness Control Register can be read or
write. Step 0 corresponds to the minimum step where the
current is less than 10µA. Steps 1 to 255 represent the linear
steps between 0.39% and 100% duty cycle with approximately
0.39% duty cycle adjustment per step.
• An SMBus Write Byte cycle to Register 0x00 sets the
• An SMBus Read Byte cycle to Register 0x00 returns the
ADDRESS
PWM brightness level only if the backlight controller is in
SMBus mode (see Table 3 Operating Modes selected by
Device Control Register Bits 1 and 2).
programmed PWM brightness level, regardless of the
value of PWM_SEL.
0x00
0x01
0x02
0x03
0x07
0x08
0x09
PWM Brightness Control Register BRT[7..0] = 256 steps of DPWM duty cycle brightness control
Device Control Register
Fault/Status Register
Identification Register
DC Brightness Control Register
Configuration Register
Output Channel Mask/Fault
Readout Register
REGISTER
19
PWM_MD = PWM mode select bit (1 = absolute brightness, 0 = % change), default = 0
PWM_SEL = Brightness control select bit (1 = control by PWMI, 0 = control by SMBus), default = 0
BL_CTL = BL On/Off (1 = On, 0 = Off), default = 0
2_CH_SD = Two LED output channels are shutdown (1 = shutdown, 0 = OK)
1_CH_SD = One LED output channel is shutdown (1 = shutdown, 0 = OK)
BL_STAT = BL status (1 = BL On, 0 = BL Off)
OV_CURR = Input overcurrent (1 = Overcurrent condition, 0 = Current OK)
THRM_SHDN = Thermal Shutdown (1 = Thermal fault, 0 = Thermal OK)
FAULT = Fault occurred (Logic “OR” of all of the fault conditions)
MFG[3..0] = Manufacturer ID (16 vendors available. Intersil is vendor ID 9)
REV[2..0] = Silicon rev (Rev 0 through Rev 7 allowed for silicon spins)
BRTDC[7..0] = 256 steps of DC brightness control
VSC[1..0] = Short circuit thresholds selection
FSW[2] = Switching frequencies selection
CH[5..0] = Output Channel Read and Write. In Write, 1 = Channel Enabled, 0 = Channel Disabled.
In Read, 1 = Channel OK, 0 = Channel Not OK/Channel disabled
TABLE 2B. DATA BIT DESCRIPTIONS
VSC1
0
1
1
ISL97635
PWM_MD PWM_SEL
f
SW
0
1
X
1
0
f
f
VSC0
SW
SW
X
0
1
• An SMBus setting of 0xFF for Register 0x00 sets the
• An SMBus setting of 0x00 for Register 0x00 sets the
• Default value for Register 0x00 is 0xFF.
Device Control Register (0x01)
This register has 2 bits that control the operating mode of the
backlight controller and a single bit that controls the BL
ON/OFF state. The remaining bits are reserved. The bit
assignment is shown in Figure 24. All other bits in the Device
Control Register will read as low unless otherwise written.
Bits 7 and 6 are not implemented and will always read low.
= 600kHz
= 1.2MHz
backlight controller to the maximum brightness.
backlight controller to the minimum brightness output in
which the LED current is guaranteed to be less than 10µA.
1
0
0
DATA BIT DESCRIPTIONS
No VSC error detection
VSC = 3.1V ±15%
VSC = 8V ±15%
OPERATION
PWMI Mode
SMBus Mode
SMBus and PWMI mode with DPST
OPERATION
MODE
December 22, 2008
FN6434.2