MC34844AEP Freescale Semiconductor, MC34844AEP Datasheet - Page 44

• Manufacturer Part Number: MC34844AEP
• Description: IC LED DVR BACKLIGHT 10CH 32QFN
• Manufacturer: Freescale Semiconductor

Specifications of MC34844AEP

• Constant Current: Yes
• Internal Driver: Yes
• Type - Primary: Backlight
• Mounting Type: Surface Mount
• Topology: PWM, Step-Up (Boost)
• Number Of Outputs: 10
• Frequency: Adjustable/Selectable
• Voltage - Supply: 7 V ~ 28 V
• Voltage - Output: 60V
• Package / Case: 32-VFQFN Exposed Pad
• Operating Temperature: -40°C ~ 105°C
• Operating Supply Voltage: 7 V to 28 V
• Maximum Supply Current: 10 mA
• Maximum Power Dissipation: 3.9 W
• Maximum Operating Temperature: + 105 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

REGULATORS
the 7.0 to 28 V range. This is stepped down internally by
LDOs to 2.5 V (VDC1 and VDC3) and 6 V (VDC3) for
powering internal circuitry. If the input voltage falls below the
UVLO threshold, the device automatically enters in shut
down mode.
the ENABLE and PWM signals, is very important to assure a
good performace of the part.
SCK bus lines, resulting in three distinct operation modes:
44
34844A
FUNCTIONAL DESCRIPTION
FUNCTIONAL INTERNAL BLOCK DESCRIPTION
1. Apply V
2. Wait for a couple of miliseconds (~2.0 ms) to let the
3. Take the EN pin high, or keep it low depending on the
4. Apply the PWM signal
The 34844A is designed to operate from input voltages in
Power UP Sequence:
The power up sequence for applying V
It is recommended to follow this sequence:
Operating Modes:
The device can be operated by the EN pin and/or SDA/
logic and internal regulators get settled
operating mode
IN
first
MC34844 - Functional Block Diagram
Logic Control
Regulator / Power down
Protection / Failure Detection
Regulators / Power Down
Optical and Temperature Control
Over-temperature Protection
Under-voltage Protection
Serial Interface Control
Over-voltage Protection
FUNCTIONAL INTERNAL BLOCK DESCRIPTION
Over-current Protection
LED Open Protection
3 Internal Regulators
Logic Control
PWM Dimming
Figure 25. Functional Internal Block Diagram
IN
LED Channels
, with respect to
Protection / Failure Detection
Boost
• Manual mode, there is no I
• SM Bus mode, EN pin must be tied low and the device is
• I
must be tied low, and the EN pin controls the ON/OFF
operation. To shutdown the part in Manual mode, first the
PWM pin should be taken low followed by the EN pin. The
part will not shut down unless V
below 30 V.
turned ON by any activity on the bus lines. The part shuts
down if the bus lines are held low for more than 30 ms, the
30 ms watchdog timer can be disabled by I
SETI2C bit high) or tying the EN pin high. In Sleep mode
(EN bit=0) the device reduces the power consumption by
leaving “alive” only the blocks required for I
communication.To shutdown the part in SM Bus mode, the
EN bit should first be a '0', then the SCK and SDA should
be taken low.
(SETI2C bit = 1) right after the IC is turned ON, it prevents
the part from being turned ON/OFF by the bus. Sleep
mode is also present and it is intended to save power, but
still keep the IC prepared to communicate by I
taking the EN bit low and then the EN pin low, the part
enters into a shutdown mode.
2
C mode, has to be configured by I
LED Channels
Boost
Analog Integrated Circuit Device Data
2
C capability, the bus line pins
OUT
Freescale Semiconductor
collapses to a voltage
2
C communication
2
2
C (setting
C
2
C. By