DS3988T+T&R Maxim Integrated Products, DS3988T+T&R Datasheet - Page 16

• Manufacturer Part Number: DS3988T+T&R
• Description: Display Drivers 8-Ch CCFL Controller All N-FET Drive, La
• Manufacturer: Maxim Integrated Products

Specifications of DS3988T+T&R

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8-Channel Cold-Cathode
Fluorescent Lamp Controller
The DS3988’s Register Map is shown in Table 1.
Detailed register and bit descriptions follow in the sub-
sequent tables.
Soft-Start Profile (SSPx) Registers—Each of the four
soft-start profile registers (SSP1–4) contains two 4-bit
codes that determine the MOSFET’s duty cycle (MDC)
for two clock cycles each (see Figure 6) at the begin-
ning of each DPWM burst. Table 2 shows the duty
cycles that correspond to each code. Selecting the
Most Recent Value instructs the DS3988 to use the
MOSFET duty cycle that was used for the last lamp
cycle of the previous burst.
Table 1. Register Map
*All the configuration settings are saved in nonvolatile (EEPROM) memory.
16
ADDRESS
F8-FFh
BYTE
F0h
F1h
F2h
F3h
F4h
F5h
F6h
F7h
____________________________________________________________________
SSP1
SSP2
SSP3
SSP4
CR1
CR2
CR3
Reserved
User
Memory
NAME
BYTE
Detailed Register Descriptions
DEFAULT*
FACTORY
21h
43h
65h
77h
00h
08h
00h
00h
—
MDC code for soft-start lamp cycles 3, 4
MDC code for soft-start lamp cycles 7, 8
MDC code for soft-start lamp cycles 11, 12
MDC code for soft-start lamp cycles 15, 16
Do not modify. If it has been modified, restore to all zeros.
DPD
BIT 7
LD2
EE
—
FRS
LD1
BIT 6
EE
—
ARD
BIT 5
LD0
EE
Table 2. MOSFET Duty Cycle (MDC)
Codes for Soft-Start Settings
*The most significant bit of each MDC code is ignored.
—
MDC CODE (BINARY)*
RGSO
LSR1
BIT 4
EE
—
X000
X001
X010
X011
X100
X101
X110
X111
MDC code for soft-start lamp cycles 1, 2
MDC code for soft-start lamp cycles 5, 6
MDC code for soft-start lamp cycles 9, 10
MDC code for soft-start lamp cycles 13, 14
DPSS
BIT 3
LSR0
EE
—
Fixed at 0%
Fixed at 3%
Fixed at 6%
Fixed at 9%
Fixed at 13%
Fixed at 16%
Fixed at 19%
Most Recent Value
POSCR1
BIT 2
LFSS
EE
—
MOSFET DUTY CYCLE
POSCR0
POSCS
BIT 1
EE
—
UMWP
BIT 0
LOC
EE
—