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PDF XRP6840 Data sheet ( Hoja de datos )
| Número de pieza | XRP6840 | |
| Descripción | 4.3A Supercapacitor Flash LED Driver | |
| Fabricantes | Exar Corporation | |
| Logotipo |  |
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December 2009
XRP6840
4.3A Supercapacitor Flash LED Driver with I2C
Rev. 1.0.0
GENERAL DESCRIPTION
The XRP6840 is a controlled-current dual-cell
supercapacitor charger and high power LED
driver. Operating from a standard lithium-ion
battery, the XRP6840 provides up to 4.3A of
programmable Flash LED current and up to
600mA and 5.6V of programmable
supercapacitor charging current and voltage.
Architectured around a 2.4MHz tri-mode 1x,
1.5x and 2x charge pump, the XRP6840
charges the stacked supercapacitor to the
programmed output voltage with no more
than 600mA drawn from the battery. While
charging, an internal active balance circuitry
insures matching of the stacked capacitors’
voltages.
A standard 2-line I2C serial interface allows
the dynamic programming of LED currents in
torch and flash modes, flash timeout, channel
enable, gain control, capacitor charge voltage,
and enable. The XRP6840 comes in a 2 and 3
channel version supporting respectively
440mA/2.15A per channel and 300mA/1.45A
in torch/flash modes.
The flexibility designed into the XRP6840 can
also allow it to reverse the power flow back to
the input to prevent unintended system resets
as the battery voltage drops.
The XRP6840 is available in a lead-free,
“green”/halogen free 20-pin TQFN package.
APPLICATIONS
• High Power Torch/Strobe/Flash LED
• High Resolution Cameras
• Generic High Power Lighting
• High Power White LED Backlighting
FEATURES
• Programmable 4.3A Flash LED Driver
− Torch and Flash Modes
− 2 and 3 Channels Versions
• Programmable Supercapacitor Charger
− 600mA Adjustable Charging Current
− Programmable Supercapacitor Voltage
− In-rush Current Control
− Active Voltage Balance Control
• Tri-mode Charge Pump Architecture
− 1x, 1.5x, 2x Operation Modes
− 2.4MHz Switching Frequency
• I2C Serial Interface
• Thermal, Over Current and Output
Short Protection
• LED Short Detection
• RoHS Compliant “Green”/Halogen Free
20-pin 4mmx4mm TQFN package
TYPICAL APPLICATION DIAGRAM
Fig. 1: XRP6840 – 3 Channels Application Diagram
Exar Corporation
48720 Kato Road, Fremont CA 94538, USA
www.exar.com
Tel. +1 510 668-7000 – Fax. +1 510 668-7001
1 page  
BLOCK DIAGRAM
XRP6840
4.3A Supercapacitor Flash LED Driver with I2C
PIN ASSIGNEMENT
Fig. 3: XRP6840 Block Diagram (XRP6840A Shown)
XRP6840A – 3 Channel Version
XRP6840B – 2 Channel Version
Fig. 4: XRP6840 Pin Assignment
© 2009 Exar Corporation
5/17
Rev. 1.0.0
5 Page 
XRP6840
4.3A Supercapacitor Flash LED Driver with I2C
represent the DAC codes D2, D1, D0. They are
used to set the flash LED current levels in each
channel. Table 5 provides the DAC codes and
the corresponding nominal current levels for
each channel:
D2-D0
XRP6840A
D2-D0
XRP6840B
Code IOUT/Ch. (mA) Code IOUT/Ch. (mA)
000
001
010
011
100
101
110
111
0
400
586
770
948
1197
1291
1445
000
001
010
011
100
101
110
111
0
597
875
1127
1400
1671
1910
2150
Table 5: Nominal Flash Mode Output Current
LEDTORCH Register
LEDTORCH register bits B2 to B7, also
summarized in Table 1; they correspond to
LED1, LED2 and LED3. Bits B4, B3, B2, and
B1 represent the DAC codes D3, D2, D1, D0.
They are used to set the torch LED current
levels in each channel. Table 6 provides the
DAC codes and their corresponding nominal
current levels for each channel. Remember
that the total current that can be supported in
torch mode is 600mA divided by the gain of
the charge pump. If 2 channels are set to
440mA (a total of 880mA), even with a gain of
1X, the input current limit will clamp the total
current to approximately 600mA.
D3-D0
Code
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
XRP6840A
D3-D0
XRP6840B
IOUT/Ch. (mA) Code IOUT/Ch. (mA)
0 0000 0
23 0 0 0 1 34
46 0 0 1 0 66
66 0 0 1 1 97
86
0100
127
105 0 1 0 1 155
125 0 1 1 0 185
145 0 1 1 1 215
165 1 0 0 0 245
185 1 0 0 1 275
205 1 0 1 0 305
225 1 0 1 1 330
245 1 1 0 0 360
260 1 1 0 1 385
280 1 1 1 0 415
300 1 1 1 1 440
Table 6: Torch Mode Output Current
Addressing and Writing Data
To write data to the XRP6840 one of the
following two sequences is required:
Easy shutdown/startup sequence
[Slave Address with write bit][Data for Status]
Full shutdown/startup sequence
[Slave Address with write bit][Data for Status]
[Data for LEDFLASH][Data for LEDTORCH]
Slave address is ‘28’ Hex.
Addressing and Reading Data
To read data from the XRP6840 the following
sequence is required:
[Slave Address with read bit][Data for Status]
[Data for LEDFLASH][Data for LEDTORCH]
© 2009 Exar Corporation
11/17
Rev. 1.0.0
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet XRP6840.PDF ] | |
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