LM3553SDX/NOPB National Semiconductor, LM3553SDX/NOPB Datasheet - Page 8

• Manufacturer Part Number: LM3553SDX/NOPB
• Description: IC LED DRIVER PHOTO FLASH 12-LLP
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: Photo Flash LED (I²C Interface)r

Specifications of LM3553SDX/NOPB

• Topology: Step-Up (Boost)
• Number Of Outputs: 1
• Internal Driver: Yes
• Type - Primary: Backlight, Flash/Torch
• Frequency: 1MHz ~ 1.35MHz
• Voltage - Supply: 2.7 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 12-LLP
• Operating Temperature: -30°C ~ 85°C
• Current - Output / Channel: 1.2A
• Internal Switch(s): Yes
• Efficiency: 90%
• For Use With: LM3553SDEV - BOARD EVALUATION FOR LM3553S
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Other names: LM3553SDX

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Block Diagram
Circuit Description
CIRCUIT COMPONENTS
F
The flash enable pin, F
I
'1', the flash current level defined through the I2C interface,
will be delived to the Flash LED. If the F
during the flash pulse, the flash event will stop. In the event
that F
will continue to deliver the flash current until the safety timer
duration (set through the I2C interface) is reached.
The LM3553 does not provide a fixed off-time after the flash
pulse has ended. Most flash LED manufacturers require that
the flash pulse duration be 10% of the total Flash cycle. Ex-
ample: If the flash pulse duration is set to be 200 milliseconds
(Flash Duration Code= 0011), the recommended off time for
the LED would be 1.8 seconds. Please consult the LED man-
ufacturers datasheet for exact timing requirements.
If the LM3553 is placed in indicator mode or torch mode
through the I
then low, at the end of the flash event, the LM3553 will return
to the mode stored in the General Purpose Register.
It is recommended that an external pull-down be placed be-
tween the F
during system start-up due to unknown control logic states.
2
EN
C) for starting the flash pulse. When F
Pin
EN
is not pulled low during the flash pulse, the LM3553
EN
2
C interface and the F
pin and GND to prevent unwanted LED flashing
EN
, provides an external method (non-
EN
pin is pulled high and
EN
EN
is pulled high, logic
pin is driven low
8
T
The transmission pin (T
drawn from the battery during a PA transmission. When the
T
LM3553 will switch to the programmed torch current level.
Once the T
to the flash current if this event occurs within the original flash
duration.
It is recommended that an external pull-down be placed be-
tween the T
during system start-up due to unknown control logic states.
M/F Pin
The multi-function pin (M/F) can be configured to provide
hardware RESET or a general purpose input/output (GPIO).
All functionality is programmed through the I
interface and set in the M/F pin functionality control register
(address 0x20). The default function is a RESET, where a
logic '1' places the part in the normal operating mode, and a
logic '0' places the part into a RESET state. A reset condition
will place all LM3553 registers into their default states.
X
X
Pin
pin is driven high (logic '1') during a flash pulse, the
X
X
pin is driven low (logic '0'), the LM3553 will return
pin and GND to prevent unwanted LED flashing
X
) can be used to limit the current
20171417
2
C compatible