DS3994 Maxim Integrated Products, DS3994 Datasheet - Page 21

• Manufacturer Part Number: DS3994
• Description: 4-Channel Cold Cathode Fluorescent Lamp Controller
• Manufacturer: Maxim Integrated Products

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DataSheet
4
F5h: Control Register 2 (CR2)
F8–FBh: Burst Dimming Stagger (BDS1/2/3/4)
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BIT
BIT
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
Reserved
Reserved
POSCR0
POSCR1
NAME
UMWP
BDSC0
BDSC1
BDSC2
BDSC3
BDSC4
BDSC5
BDSC6
BDSC7
BVRS
NAME
LD0
LD1
User Memory Write Protect
0 = User Memory Write Access Blocked
1 = User Memory Write Access Permitted
DPWM Oscillator Range Select. When using an external source for the dimming clock, these bits must
be set to match the external oscillator’s frequency. When using a resistor to set the dimming
frequency, these bits plus the external resistor control the frequency.
Lamp Disable. Used to disable channels if all 4 are not required for an application.
Bright Voltage Range Select.
0 = 0.5V to 2.0V
1 = 0.0V to 3.3V
8-Bit Programmable Counter That Staggers the Start of Burst Dimming. 00h = 0ms stagger. Setting
the stagger longer than the burst dimming cycle results in the channel never turning on. See Table 2.
POSCR1
LD1
0
0
1
1
0
0
1
1
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Fluorescent Lamp Controller
POSCR0
LD0
0
1
0
1
0
1
0
1
Reserved. Should be set to zero.
Reserved. Should be set to one.
4-Channel Cold-Cathode
All Channels Enabled
4
2/4
1/2/4
DIMMING CLOCK (DPWM)
FREQUENCY RANGE (Hz)
CHANNELS DISABLED
FUNCTION
FUNCTION
22.5 to 55.0
180 to 440
45 to 110
90 to 220
NUMBER OF ACTIVE
LAMP CHANNELS
(kΩ-kHz)
K
1
2
4
8
4
3
2
1
21