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PDF DS3984 Data sheet ( Hoja de datos )

Número de pieza DS3984
Descripción 4-Channel Cold-Cathode Fluorescent Lamp Controller
Fabricantes Dallas Semiconducotr 
Logotipo Dallas Semiconducotr Logotipo



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Rev 0; 4/05
4-Channel Cold-Cathode
Fluorescent Lamp Controller
General Description
The DS3984 is a 4-channel controller for cold-cathode
fluorescent lamps (CCFLs) used to backlight liquid
crystal displays (LCDs) in TV and PC monitor applica-
tions. The DS3984 supports configurations of 1 to 4
lamps, and multiple DS3984 controllers can be cascad-
ed to support applications requiring more than 4 lamps.
LCD Televisions
LCD PC Monitors
Applications
Ordering Information
PART
TEMP RANGE
DS3984T
-40°C to +85°C
DS3984T+
-40°C to +85°C
DS3984Z
-40°C to +85°C
DS3984Z+
-40°C to +85°C
+Denotes lead-free package.
PIN-PACKAGE
32 TQFP
32 TQFP
28 SO.300
28 SO.300
Pin Configurations
TOP VIEW
LOSC 1
A0 2
PSYNC 3
POSC 4
BRIGHT 5
SVM 6
GA1 7
GB1 8
LCM1 9
OVD1 10
GA2 11
GB2 12
LCM2 13
OVD2 14
DS3984
28-SO-300
28 LSYNC
27 FAULT
26 SCL
25 SDA
24 OVD4
23 LCM4
22 GB4
21 GA4
20 OVD3
19 LCM3
18 GB3
17 GA3
16 VCC
15 GND
Pin Configurations continued at end of data sheet.
Typical Operating Circuit appears at end of data sheet.
Features
High-Density CCFL Controller for LCD TV and PC
Monitor Backlights
Can Be Easily Cascaded to Support More Than
4 Lamps
Minimal External Components
Analog Brightness Control
Per-Channel Lamp Control Ensures Equal
Brightness Among Lamps and Maximizes Lamp
Life
Gate Driver Phasing Minimizes DC Supply Current
Surges
Per-Channel Lamp Fault Monitoring for Lamp
Open, Lamp Overcurrent, Failure to Strike, and
Overvoltage Conditions
Accurate (±5%) Independent On-Board Oscillators
for Lamp Frequency (40kHz to 80kHz) and DPWM
Burst Dimming Frequency (22.5Hz to 440Hz)
Can Be Synchronized to External Sources for the
Lamp and DPWM Frequencies
<10% to 100% Dimming Range
Programmable Soft-Start Minimizes Audible
Transformer Noise
I2C-Compatible Serial Port and On-Board
Nonvolatile (NV) Memory Allow Device
Customization
8-Byte NV User Memory for Storage of Serial
Numbers and Date Codes
4.5V to 5.5V Single-Supply Operation
-40°C to +85°C Temperature Range
32-Lead TQFP (7mm x 7mm) Package or
28-Pin SO (300 mils) Package
I2C is a trademark of Philips Corp. Purchase of I2C compo-
nents from Maxim Integrated Products, Inc., or one of its subli-
censed Associated Companies, conveys a license under the
Philips I2C Patent Rights to use these components in an I2C
system, provided that the system conforms to the I2C Standard
Specification as defined by Philips.
______________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

1 page




DS3984 pdf
4-Channel Cold-Cathode
Fluorescent Lamp Controller
(VCC = +5.0V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics
ACTIVE SUPPLY CURRENT
vs. SUPPLY VOLTAGE
14
fLF:OSC = 71kHz
13
12 GATE QC = 3.5nC
11
10
9
DPWM = 100%
DPWM = 50%
8
7
6
5
4.5
DPWM = 10%
SVM = 0V
4.7 4.9 5.1 5.3
SUPPLY VOLTAGE (V)
5.5
ACTIVE SUPPLY CURRENT
vs. TEMPERATURE
14.0
VCC = 5.5V
13.5 VCC = 5.0V
13.0 VCC = 4.5V
12.5
12.0
11.5
11.0
10.5
10.0 fLF:OSC = 71kHz
9.5
GATE QC = 3.5nC
9.0
-40 -15 10
DPWM = 100%
35 60 85
TEMPERATURE (°C)
INTERNAL FREQUENCY CHANGE
vs. TEMPERATURE
4
3
2
LAMP FREQUENCY
1
0
-1 DPWM FREQUENCY
-2
-3
-4
-40
-15 10 35 60
TEMPERATURE (°C)
85
TYPICAL OPERATION AT 12V
10µs
5.0V GA
10µs
5.0V GB
10µs
2.0V LCM
10µs
2.0V OVD
TYPICAL OPERATION AT 15V
10µs
5.0V GA
10µs
5.0V GB
10µs
2.0V LCM
10µs
2.0V OVD
TYPICAL OPERATION AT 18V
10µs
5.0V GA
10µs
5.0V GB
10µs
2.0V LCM
10µs
2.0V OVD
TYPICAL STARTUP WITH SVM
2ms
2.0V SVM
2ms
5.0V GB
2ms
2.0V LCM
2ms
2.0V OVD
BURST DIMMING AT 150Hz AND 10%
1ms
5.0V GA
1ms
5.0V GB
1ms
2.0V LCM
1ms
2.0V OVD
_____________________________________________________________________ 5

5 Page





DS3984 arduino
4-Channel Cold-Cathode
Fluorescent Lamp Controller
ANALOG DIMMING
CONTROL VOLTAGE
0.5V
DPWM
SIGNAL
22.5Hz TO 440Hz
RESISTOR TO SET THE
DIMMING FREQUENCY
RESISTOR-SET DIMMING CLOCK
2.0V
BRIGHT
PSYNC (OUTPUT)
POSC
ANALOG DIMMING
CONTROL VOLTAGE
0.5V
DPWM
SIGNAL
EXTERNAL
DIMMING CLOCK
22.5Hz TO 440Hz
22.5Hz to 440Hz
EXTERNAL DIMMING CLOCK
2.0V
BRIGHT
PSYNC (OUTPUT)
POSC
Figure 3. DPWM Source Configuration Options
DPWM
SIGNAL
22.5Hz TO 440Hz
BRIGHT
PSYNC (OUTPUT)
POSC
Figure 4. The DPWM Receiver Configuration
To generate the DPWM signal internally, the DS3984
requires a clock (referred to as the dimming clock) to
set the DPWM frequency. The user can supply the dim-
ming clock by setting POSCS = 1 in CR1 and applying
an external 22.5Hz to 440Hz signal at the POSC pin, or
DS3984’s clock can be generated by the DS3984’s
oscillator (set POSCS = 0 in CR1), in which case the
frequency is set by an external resistor at the POSC
pin. These two dimming clock options are shown in
Figure 3. Regardless of whether the dimming clock is
generated internally or sourced externally, the POSC1
and POSC2 bits in CR2 must be set to match the
desired dimming clock frequency.
When the DPWM signal is generated internally, its duty
cycle (and, thus, the lamp brightness) is controlled by a
user-applied analog voltage at the BRIGHT input. A
BRIGHT voltage less than 0.5V will cause the DS3984 to
operate with the minimum burst duty cycle, providing
the lowest brightness setting, while any voltage greater
than 2.0V will cause a 100% burst duty cycle (i.e., lamps
always being driven), which provides the maximum
brightness. For voltages between 0.5V and 2V the duty
cycle will vary linearly between the minimum and 100%.
The internally generated DPWM signal is available at
the PSYNC I/O pin (set RGSO = 0 in CR1) for sourcing
to other DS3984s, if any, in the circuit. This allows all
DS3984s in the system to be synchronized to the same
DPWM signal. The DS3984 that is generating the
DPWM signal for other DS3984s in the system is
referred to as the DPWM source.
When the DPWM signal is provided by an external
source, either from the PSYNC pin of another DS3984 or
from some other user-generated source, it is input into the
PSYNC I/O pin of the DS3984. In this mode, the BRIGHT
and POSC inputs are disabled and should be grounded
(see Figure 4). When multiple DS3984s are used in a
design, DS3984s configured to use externally generated
DPWM signals are referred to as DPWM receivers.
Lamp Frequency Configuration
The DS3984 can generate its own lamp frequency clock
internally (set LFSS = 0 in CR1), which can then be
sourced to other DS3984s if required, or the lamp clock
can be supplied from an external source (set LFSS = 1 in
CR1). When the lamp clock is internally generated, the
frequency (40kHz to 80kHz) is set by an external resistor
at the LOSC. In this case, the DS3984 can act as a lamp
frequency source because the lamp clock is output at
the LSYNC I/O pin for synchronizing any other DS3984s
configured as lamp frequency receivers.
The DS3984 acts as a lamp frequency receiver when
the lamp clock is supplied externally. In this case, a
40kHz to 80kHz clock must be supplied at the LSYNC
I/O. The external clock can originate from the LSYNC
I/O of a DS3984 configured as a lamp frequency
source or from some other source.
____________________________________________________________________ 11

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