NCP5623C View Datasheet(PDF) - ON Semiconductor
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MFG CO.
NCP5623C Datasheet PDF : 11 Pages
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NCP5623C
The dimming is built with 30 steps and the time delay
encoded into the second byte of the I2C transaction: see
Table 1.
When the gradual dimming is deactivated (B7 = B6 = 0,
B5 = 1), the output current is straightforwardly set up to the
level defined by the contain of the related register upon
acknowledge of the output current byte.
The gradual dimming sequence must be set up before a
new output current data byte is send to the NCP5623C . At
this point, the brightness sequence takes place when the new
data byte is acknowledged by the internal I2C decoder. Since
the six registers are loaded on independent byte flow
associated to the I2C address, any parameter of the
NCP5623C chip can be updated ahead of the next function
as depicted in Table 2.
Table 2. Basic Programming Sequences
I2C Address COMMAND Bits[7:0]
$72
000X XXXX
$72
0010 0000
0011 1111
Operation
System Shut Down
Set Up the ILED current
$72
0100 0000
0101 1111
$72
0110 0000
0111 1111
Set Up the PWM1
Set Up the PWM2
Note
Bits[4:0] are irrelevant
ILED register
Bits[4:0] contain the IMAX value as defined by the
Iref value
PWM1
Bits[4:0] contain the PWM value
PWM2
Bits[4:0] contain the PWM value
$72
1000 0000
1001 1111
Set Up the PWM3
PWM3
Bits[4:0] contain the PWM value
$72
1010 0000
Set Up the IEND Upward
1011 1111
UPWARD
Bits[4:0] contain the IEND value
$72
1100 0000
Set Up the IEND Downward
1101 1111
DWNWRD
Bits[4:0] contain the IEND value
$72
1110 0000
Set Up the Gradual Dimming time
GRAD
1111 1111
and run the sequence
Bits[4:0] contain the TIME value
The number of step for a given sequence, depends upon
the start and end output current range: since the IPEAK
value is encoded in the Bits[4:0] binary scale, a maximum
of 31 steps is achievable during a gradual dimming
operation.
The number of steps will be automatically recalculated by
the chip according to the equation:
Nstep = | existing step position − new step position |
As an example, assuming the previously programmed
step was 5 and the new one is 15, then we will have 10 steps
to run between the actual location to the end value. If the
timing was set at 16 ms, the total gradual dimming sequence
will be 160 ms.
To select the direction of the gradual dimming (either
Upward or Downward), one shall send the appropriate
register before to activate the sequence as depicted below:
1010 1111 ³ 1110 0011 ³ select an UPWARD sequence
with 24 ms/step, the end IPEAK current being (IREF *
2400) / (31 − 16) mA.
1100 0001 ³ 1110 0100 ³ select the DOWNWARD
sequence with 32 ms/step, the end IPEAK current being
(IREF * 2400) / (31 − 1) mA.
Table 3. Output Current Programmed Value (ILED = F(Step))
Step
ILED (mA)
Step
ILED (mA)
Step
0 / $00
0
9 / $09
1.25
18 / $12
1 / $01
0.92
10 / $0A
1.31
19 / $13
2 / $02
0.95
11 / $0B
1.38
20 / $14
3 / $03
0.98
12 / $0C
1.45
21 / $15
4 / $04
1.02
13 / $0D
1.53
22 / $16
5 / $05
1.06
14 / $0E
1.62
23 / $17
6 / $06
1.10
15 / $0F
1.72
24 / $18
7 / $07
1.15
16 / $10
1.84
25 / $19
8 / $08
1.20
17 / $11
1.97
26 / $1A
ILED (mA)
2.12
2.30
2.50
2.76
3.06
3.45
3.94
4.60
5.52
Step
27 $1B
28 / $1C
29 / $1D
30 / $1E
31 / $1F
ILED (mA)
6.90
9.20
13.80
27.60
27.60
NOTE: The table assumes IREF = 11.5 mA
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