LM3509SDEV National Semiconductor, LM3509SDEV Datasheet - Page 15

• Manufacturer Part Number: LM3509SDEV
• Description: BOARD EVALUATION FOR LM3509SD
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM3509SDEV

• Current - Output / Channel: 40mA
• Outputs And Type: 2, Non-Isolated
• Voltage - Output: 21V
• Features: Dimmable, I²C Interface
• Voltage - Input: 2.7 ~ 5.5V
• Utilized Ic / Part: LM3509
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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