LP3913SQ-AR/NOPB National Semiconductor, LP3913SQ-AR/NOPB Datasheet - Page 50

• Manufacturer Part Number: LP3913SQ-AR/NOPB
• Description: IC PMU FLASH MEM PROGRMMBL 48LLP
• Manufacturer: National Semiconductor
• Series: PowerWise®r

Specifications of LP3913SQ-AR/NOPB

• Applications: Handheld/Mobile Devices
• Voltage - Supply: 2.5 V ~ 6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-LLP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Supply: -
• Other names: LP3913SQ-ARTR

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BUCK3: Synchronous Magnetic DC/
DC Converter
The LP3913 is equipped with a synchronous Buck3 magnetic
DC-DC converter to supply power to the Flash memory that
has a typical 1.7V-3.3V operating voltage. This voltage is low-
er than the maximum battery voltage (4.2V typically for Li-
polymer cells) and higher than the minimum battery voltage
BUCK3 CONTROL REGISTER
Buck3 is controlled through its dedicated control register.
Buck3 is enabled through the power-on sequencing. The sys-
tem processor is required to select the desired Buck3 output
voltage through bits D4-0 before enabling it by setting bit D6
in the control register. Buck3 is also disabled when 5'b00000
Schematic Section for Buck3 Operation
50
(typically 2.8V). Therefore, in order to provide 3.3V, regard-
less of the battery voltage, the Buck3 converter efficiently
steps down the battery voltage. The Buck3 automatically
switches between PWM and PFM modes depending on the
load.
By setting bit D6 of the Buck3 control register, the Buck3 will
be forced to operate using PWM modulation regardless of the
load. By default, this bit is cleared.
is programmed in the register field D4-0, regardless of the
state of the bit D6. When Buck3 is disabled, its output is in-
ternally tied low through a 1MΩ resistor. If D4-0 is set to
5'b00000, the 1MΩ resistor is disconnected.
The default output voltage for the buck can be set to 1.8V,
2.5V, 2.8V, 3.3V, and is factory programmable.
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