NCP5623C View Datasheet(PDF) - ON Semiconductor
Part Name
Description
MFG CO.
NCP5623C Datasheet PDF : 11 Pages
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NCP5623C
B7
B6
B5
B4
B3
B2
B1
B0
Byte#1 : I2C Physical Address, based 7 bits : % 011 1001 ³ $39 *
0
1
1
1
0
0
1
R/W
Byte#2 : DATA register
RLED2
RLED1
RLED0
BLED4
BLED3
BLED2
BLED1
BLED0
*Note: according to the I2C specifications, the physical address is based on 7 bits out of the SDA byte, the 8th bit representing the R/W command.
Since the NCP5623C is a receiver only, the R/W command is 0 and the hexadecimal byte send by the MCU is %0111 0010 = $72
B[7:5] : Internal Register Selection:
B7
B6 B5
Function
0
0
0 Chip Shut Down ³ all LED current = zero
0
0
1 Set up the maximum Output LED Current
0
1
0 PWM1 : LED1 control
0
1
1 PWM2 : LED2 control
1
0
0 PWM3 : LED3 control
1
0
1 Set the Upward Iend target
1
1
0 Set the Downward Iend target
1
1
1 Set the number of steps and activate the Gradual Dimming
The contain of bits B[4:0] depends upon the type of function selected by bits B[7:5] as depicted in Table 1
Table 1. Internal Register Bits Assigment
B7 B6 B5
B4
B3
B2
B1
B0
Comments
0
0
0
X
X
X
X
X
Shut down
0
0
1
16
8
4
2
1
Output LED Step, see Figure 4 (Note 11)
0
1
0 BPWM16 BPWM8 BPWM4
BPWM2
BPWM1 PWM1
0
1
1 BPWM16 BPWM8 BPWM4
BPWM2
BPWM1 PWM2
1
0
0 BPWM16 BPWM8 BPWM4
BPWM2
BPWM1 PWM3
1
0
1
GDIM5
16
GDIM4
8
GDIM3
4
GDIM2
2
GDIM1
1
Set Gradual Dimming
Upward Iend Target (Note 12)
1
1
0
GDIM5
16
GDIM4
8
GDIM3
4
GDIM2
2
GDIM1
1
Set Gradual Dimming
Downward Iend Target (Note 12)
1
1
1
GDIM5
GDIM4
GDIM3
128 ms
64 ms
32 ms
GDIM2
16 ms
GDIM1
8 ms
Gradual Dimming
Step Number & run
11. The programmed current applies to the three LED simultaneously, the gradual dimming is not engaged
12. The bit values represent the steps count, not the ILED current: see equations 1 & 2, page 7, to derive the ILED value.
GRADUAL DIMMING
The purpose of that function is to gradually Increase or
Decrease the brightness of the backlight LED upon
command from the external MCU. The function is activated
and controlled by means of the I2C protocol.
In order to avoid arithmetic division functions at silicon
level, the period (either upward or downward) is equal to the
time defined for each step, multiplied by the number of
steps.
To operate such a function, the MCU will provide three
information:
1 – The target current level (either upward or downward)
2 – The time per step
3 – The Upward or Downward mode of operation
When a new gradual dimming sequence is requested, the
output current increases, according to an exponential curve,
from the existing start value to the end value. The end current
value is defined by the contain of the Upward or Downward
registers, the width of each step is defined by the third
register, the number of step being in the 1 to 30 range. In the
event of software error, the system checks that neither the
maximum output current (30 mA), nor the zero level are
forced out of their respective bounds. Similarly, software
errors shall not force the NCP5623C into an uncontrolled
mode of operation.
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