XRP6840 Exar Corporation, XRP6840 Datasheet - Page 11

• Manufacturer Part Number: XRP6840
• Description: 4.3a Supercapacitor Flash Led Driver With I2c
• Manufacturer: Exar Corporation

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:
LEDTORCH
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.
that the total current that can be supported in
torch mode is 600mA divided by the gain of
the charge pump.
440mA (a total of 880mA), even with a gain of
1X, the input current limit will clamp the total
current to approximately 600mA.
© 2009 Exar Corporation
D2-D0
LEDTORCH Register
D3-D0
0 0 0 0
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
0 1 0 1
0 1 1 0
0 1 1 1
1 0 0 0
1 0 0 1
1 0 1 0
1 0 1 1
1 1 0 0
1 1 0 1
1 1 1 0
1 1 1 1
Code
Code
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
Table 5: Nominal Flash Mode Output Current
Table 6: Torch Mode Output Current
I
I
OUT
OUT
XRP6840A
XRP6840A
register
/Ch. (mA)
/Ch. (mA)
1197
1291
1445
400
586
770
948
105
125
145
165
185
205
225
245
260
280
300
23
46
66
86
0
0
If 2 channels are set to
bits
D2-D0
D3-D0
0 0 0 0
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
0 1 0 1
0 1 1 0
0 1 1 1
1 0 0 0
1 0 0 1
1 0 1 0
1 0 1 1
1 1 0 0
1 1 0 1
1 1 1 0
1 1 1 1
Code
Code
0 0 0
0 0 1
0 1 0
0 1 1
1 0 0
1 0 1
1 1 0
1 1 1
B2
I
to
I
OUT
OUT
XRP6840B
XRP6840B
Remember
/Ch. (mA)
/Ch. (mA)
B7,
1127
1400
1671
1910
2150
4
597
875
127
155
185
215
245
275
305
330
360
385
415
440
4
34
66
97
0
0
.
.
3
3
A
A
also
S
S
u
u
11/17
p
p
e
e
r
r
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.
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]
c
c
Addressing and Writing Data
Addressing and Reading Data
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Rev. 1.0.0
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