NCP1840Q8A6MNG ON Semiconductor, NCP1840Q8A6MNG Datasheet - Page 14

• 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

Output Control Register
set the status, either ON or OFF, of all 8 channels. As shown
in the following table, each bit in the register corresponds to
one of the 8 LED channels. Each channel will be turned ON
with a 1 loaded into the corresponding bit and will be turned
Main Status Register
indicate the operating condition of the part and is read−only.
As shown in the following table, bit D0 indicates either
normal operation (0) or an over temperature condition (1).
When the on−chip temperature sensor detects an
over−temperature condition, it will turn off all LED outputs,
along with the charge pump, and set bit D0 to a logic one. If
the over−temperature condition goes away, bit D0 will
automatically reset to a logic zero and the part will resume
normal operation. Therefore, bit D0 of this register can be
read and used to help determine if an over−temperature
Fault Management
intended to provide increased performance and reliability to
both the system and the part itself:
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OUTPUT CONTROL REGISTER DESCRIPTION
MAIN STATUS REGISTER DESCRIPTION
The Output Control Register on the NCP1840 is used to
The Main Status Register of the NCP1840 is used to
The NCP1840 has several fault management features
D7
Each LED output will detect if it is shorted to the
charge pump output and if so will turn that particular
channel’s circuitry OFF. This saves power consumption
that would otherwise be lost and provides the user with
the ability to ensure that unused channels are turned
OFF by tying them to the charge pump output.
The charge pump output will detect any over−current
events and automatically limit the current to less than
800 mA. This helps to prevent any damage to the chip
and the system due to elevated current on this output.
The charge pump output will detect a short−circuit
event (less than 0.7 V) and limit the current to the
soft−start limit of less than 94 mA. This helps to
prevent damage to the chip and the system that could
potentially be seen with the output being
short−circuited to ground.
The charge pump will reset itself to 1x mode if it
reaches an overvoltage level (5.5 V to 6 V). This helps
to prevent damage to the chip and the system in the
0
D6
0
Register Bit (1 = ON, 0 = OFF)
Corresponding LED Channel
D5
0
D4
0
D3
0
0 = Normal Operation
1 = Low Power Mode
D2
http://onsemi.com
LED8
D7
14
LED7
D6
OFF with a 0 loaded into that bit. When an LED channel is
turned ON, the current level and PWM duty cycle of that
channel will be dictated by the data that is loaded into its
Current Level Register and PWM Register. It is important to
note that any unused LED channel should not be turned ON.
condition currently exists on the part. Likewise, bit D2
indicates either normal operation (0) or low power mode
operation (1). When all LED outputs are turned OFF and
there is no I
itself in a low power mode and set bit D2 to a logic one.
When the Master wakes the device up with I
communication, bit D2 will be set to a logic zero once the
entire chip is ready to run in normal operation. Therefore,
when the Master wakes up the device, it can read bit D2 and
wait for this bit to change to 0, indicating the return to normal
operation.
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event that the supply voltage increases while the charge
pump is operating in the 1.33x, 1.5x, or 2x mode.
If the external resistor, R
output current and the internal reference current, is too
small or otherwise short−circuits, the NCP1840 will
detect this over−current condition and turn off the
reference current and LED outputs. This helps to
prevent damage to the chip and system due to elevated
currents that would be present.
The NCP1840 has an on−chip over temperature sensor
that will detect any over−temperature condition (130°C
− 163°C) and turn off all LED outputs along with the
charge pump. In an over−temperature state, bit D0 of
the Main Status Register will be set to a logic one.
When the over−temperature condition goes away, the
part will resume normal operation and bit D0 will be set
to a logic zero. The D0 bit of the Main Status Register
can be read through the I
provide feedback to the Master controller. This helps to
protect the chip and system in the event that the
temperature increases beyond a safe operating
condition.
D1
0
LED6
D5
2
C communication for 5 ms, the part will put
LED5
D4
1 = Over Temperature
0 = Normal Operation
LED4
D3
BIAS
2
C interface and can be used to
, used to set the maximum
D0
LED3
D2
LED2
D1
LED1
D0
2
C