LM3530UME-25A/NOPB National Semiconductor, LM3530UME-25A/NOPB Datasheet - Page 18

• Manufacturer Part Number: LM3530UME-25A/NOPB
• Description: IC LED DRVR PRGRAM I2C 10LED SMD
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LM3530UME-25A/NOPB

• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Backlight
• Type - Secondary: White LED
• Frequency: 500kHz
• Voltage - Supply: 2.7 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 12-XFBGA
• Operating Temperature: -40°C ~ 85°C
• Current - Output / Channel: Adjustable
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Other names: LM3530UME-25A/NOPBTR

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LED CURRENT CONTROL
The LED current is is a function of the Full Scale Current, the
Brightness Code, and the PWM input duty cycle. The Bright-
The following sections describe each of these LED current
control methods.
PWM + I
PWM + I
‘1’ to the Enable PWM bit (General Configuration Register bit
[5]) and writing a ‘1’ to the I
Configuration Register bit 0). This makes the LED current a
function of the PWM input duty cycle (D), the Full-Scale LED
current (I
of Full-Scale LED current is set by the code in the Brightness
Zone Boundary Code
2
2
LED_FS
C-compatible current control is enabled by writing a
C-COMPATIBLE CURRENT CONTROL
0x00
0x01
0x02
0x03
0x04
), and the % of full-scale LED current . The %
TABLE 1. Ideal Zone Boundary Settings with Hysteresis (Lower 5 Codes)
2
C Device Enable bit (General
Typical Zone Boundary
FIGURE 10. Current Control Block Diagram
Threshold
15.8mV
15.8mV
15.8mV
15.8mV
19.7mV
18
ness Code can either come from the BRT Register (0xA0) in
I2C Compatible Current Control, or from the ALS Zone Target
Registers (Address 0x70-0x74) in Ambient Light Current Con-
trol.
Control Register. The LED current using PWM + I
patible Control is given by the following equation:
BRT is the percentage of Full Scale Current as set in the
Brightness Control Register. The Brightness Control Register
can have either exponential or linear brightness mapping de-
pending on the setting of the BMM bit (bit [1] in General
Configuration Register).
Typical Threshold +
Figure 10
Hysteresis
19.3mV
19.3mV
19.3mV
19.3mV
23.2mV
shows the current control block diagram.
Typical Threshold -
Hysteresis
12.3mV
12.3mV
12.3mV
12.3mV
16.2mV
30086625
2
C-Com-