NCP1840Q8A6MNG ON Semiconductor, NCP1840Q8A6MNG Datasheet - Page 8

• Manufacturer Part Number: NCP1840Q8A6MNG
• Description: LED Lighting Drivers PRGRM MULTI LED DRIVER
• Manufacturer: ON Semiconductor

Specifications of NCP1840Q8A6MNG

• Product Category: LED Lighting Drivers
• Rohs: yes
• Input Voltage: 3 V to 5.5 V
• Operating Frequency: 400 kHz
• Maximum Supply Current: 0.75 mA
• Output Current: 30 mA
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: QFN-20
• Minimum Operating Temperature: - 40 C

Constant Current Control
regulated constant current sources. The maximum current
per channel is 30 mA but can be reduced by adjusting the
resistor R
ground. R
and 20.5 kW. The maximum current per channel can be
calculated with the following equation:
PWM Control
each of its 8 channels, allowing each channel to be dimmed
independent of the other channels and without sacrificing
the LED color output. Programming PWM duty cycle is
achieved by loading data into channel−specific registers
through the I
LED can be calculated by multiplying the duty cycle
percentage by the typical PWM period of 575 ms.
Charge Pump
QUAD−MODE (1x, 1.33x, 1.5x, and 2x) charge pump. This
allows for higher forward voltage LEDs and/or multiple
LEDs in series per channel to be driven with a low−voltage
supply. In order to optimize efficiency while maintaining
constant current regulation, the NCP1840 automatically
senses when it should change charge pump modes based on
the voltage across the LED current sources. By utilizing the
1.33x mode, approximately 10% more efficiency than a
typical 1.5x mode is achieved.
pump output voltage will be approximately equal to the
input supply voltage. If the output voltage is sufficient to
regulate all LED currents, the device remains in this mode.
However, if the input voltage is insufficient to regulate the
current in all active channels, the device automatically
The NCP1840 has 8 LED channels that are individually
The NCP1840 provides 6−bit PWM duty cycle control for
The NCP1840 incorporates a high efficiency, low noise,
The NCP1840 powers up in 1x mode where the charge
35
30
25
20
15
10
5
0
1
BIAS
BIAS
3
2
5
C serial interface. The typical on time of the
, which is placed between the R
is required and can vary between 10.25 kW
7
I
9
max
11
+ 250 *
13
15
Figure 12. Logarithmic Output Current (R
17
1.23 V
R
19
BIAS
21
23
25
OPERATION DESCRIPTION
BIAS
27
29
pin and
http://onsemi.com
31
8
each of the 8 channels to be fully programmable via a 5−bit
DAC on each output, allowing for the desired luminance to
be achieved for each channel. Programming the current
level is achieved by loading data into channel−specific
registers through the I
levels are logarithmic, providing a perceived linear LED
brightness to the human eye, as shown in Figure 12. This
allows for a more gradual and natural viewing change in
LED brightness between levels.
switches into 1.33x mode. In this mode, the output voltage
is approximately equal to 1.33 times the input supply
voltage. If the input voltage is insufficient again to maintain
current regulation in all active channels, the device will
automatically switch to the 1.5x mode. In this mode, the
output voltage will be approximately equal to 1.5 times the
input supply voltage. If the input voltage is still insufficient
to maintain the constant current regulation in all active
channels, the device will automatically switch to the 2x
mode where the output voltage is approximately equal to
two times the input supply voltage. In all modes, if the
device detects a sufficient input voltage to drive all LED
currents in 1x mode, it will automatically change back to 1x
mode to optimize efficiency.
I
through an I
being configured as a Slave device, a Master device is
required on the communication bus. The NCP1840 has a
factory programmed 7−bit Slave address of 0011011 (1B
hex). The last bit of the Slave address specifies whether a
Read (1) or Write (0) operation is to be performed. The
maximum clock frequency for the serial interface is 400 kHz
and both the SCL and SDA lines require external pull−up
resistors.
2
C Serial Interface
Additionally, the NCP1840 allows for the current through
The registers of the NCP1840 are programmed and read
BIAS
High
Low
2
C serial interface. Due to the NCP1840 only
= 10.25 KW)
0
2
C serial interface. The output current
DAC Level
31