LM3509 Datasheet, PDF (15/24 Pages) National Semiconductor (TI) – OLED Displays with Dual Current Sinks and I2C Compatible Brightness Control

REGISTER DESCRIPTIONS
There are 4, 8 bit registers within the LM3509 as detailed in Table 1.
TABLE 1. LM3509 Register Descriptions
Register Name
General Purpose (GP)
Brightness Main (BMAIN)
Brightness Sub (BSUB)
General Purpose
I/O (GPIO)
Hex Address
10
A0
B0
80
Power -On-Value
0xC0
0xE0
0xE0
0XF8
GENERAL PURPOSE REGISTER (GP)
The General Purpose register has four functions. It controls
the on/off state of MAIN and SUB/FB, it selects between Uni-
son or Non-Unison mode, provides for control over the rate of
change of the LED current (see Brightness Rate of Change
Description), and selects between White LED and OLED
mode. Figure 6 and Table 2 describes each bit available with-
in the General Purpose Register.
30004340
FIGURE 6. General Purpose Register Description
TABLE 2. General Purpose Register Bit Function
Bit
Name
Function
Power-On-Value
0
ENM
Enable MAIN. Writing a 1 to this bit enables the main current sink (MAIN).
0
Writing a 0 to this bit disables the main current sink and forces MAIN high
impedance.
1
ENS
Enable SUB/FB. Writing a 1 to this bit enables the secondary current sink (SUB/
0
FB). Writing a 0 to this bit disables the secondary current sink and forces SUB/
FB high impedance.
2
UNI
Unison Mode Select. Writing a 1 to this bit disables the BSUB register and
0
causes the contents of BMAIN to set the current in both the MAIN and SUB/
FB current sinks. Writing a 0 to this bit allows the current into MAIN and SUB/
FB to be independently controlled via the BMAIN and BSUB registers
respectively.
3
RMP0
Brightness Rate of Change. Bits RMP0 and RMP1 set the rate of change of
0
4
RMP1
the LED current into MAIN and SUB/FB in response to changes in the contents
0
of registers BMAIN and BSUB (see brightness rate of change description).
5
OLED
OLED = 0 places the LM3509 in White LED mode. In this mode both the MAIN
0
and SUB/FB current sinks are active. The boost converter ensures there is at
least 500mV at V_MAIN and V_SUB/FB.
OLED = 1 places the LM3509 in OLED mode. In this mode the boost converter
regulates V_SUB/FB to 1.25V. V_MAIN is unregulated and must be > 400mV for the
MAIN current sink to maintain current regulation.
6
Don't Care These are non-functional read only bits. They will always read back as a 1.
1
7
15
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