SSD1811_ Просмотр технического описания (PDF) - Solomon Systech
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SSD1811_ Datasheet PDF : 14 Pages
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APPLICATION NOTE 2: CONTRAST CONTROL CALCULATION
In the SSD181X/SSD1815A/SSD1815B series IC revision 2.5 onwards, there has been an update on the data information, when
using VL6 voltage regulator internal resistors and the electronic volume function, software control of the 64 contrast voltage levels
is at each voltage regulator feedback gain can be used (without adding any external resistors). The equation given is as follows:
From the above table, the formula can provide a quick estimation of the voltage generated by the software setting
and the electronic booster circuit in the IC.
VL6 −VDD = Gain ∗ (1+ Contrast) ∗Vref
β
Vref = (VBE + R ∗ (VDD − VSS) )
1+ R
where
Int. Reg Resistor
Ratio Setting
(IRS)
20Hex 21Hex 22Hex 23Hex 24Hex 25Hex 26Hex 27Hex Ext. Resistor
Gain
-3.36 -3.84 -4.38 -4.93 -5.50 -5.89 -6.54 -7.10 -(1+R2/R1)
β
90.54 89.95 89.32 88.69 88.04 87.59 86.77 86.01
96.68
and
TC
0
2
4
7
(-0.01%/°C) (-0.10%/°C) (-0.18%/°C) (-0.25%/°C)
VBE
0.025
0.523
0.520
0.517
R
0.72
0.423
0.272
0.121
*Note: There may be a calculation error of max. 6% when comparing with measurement values.
Case sample: When the voltage regulator internal resistance are used:
The liquid crystal power supply voltage VL6 can be set with the VL6 voltage regulator internal resistors (IRS pin is
pulled “H”). When selecting Ta=25°C, with VDD = 2.775V, IRS = 23hex, Contrast setting = 25hex (=37dec), Tem-
perature Compensation (TC) = 0;
By using the formula,
Vref = ( 0.025 + 0.72 ∗ (2.775 − 0) )
1 + 0.72
Vref = 1.176V
Then,
VL 6 − VDD = − 4 .93 ∗ (1 + 37 ) ∗ 1 .176
88 .69
Therefore, calculated VL6 is -8.22V.
Application of SSD181X/SSD1815A/SSD1815B to Existing LCD Modules
4
SOLOMON
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