DS2740(3)

NAME
DS2740 - High-Precision Coulomb Counter

SYNOPSIS
Voltage and Switch

36 [.]XXXXXXXXXXXX[XX][/[ memory | PIO | sensed | vis | vis_B | volthours |
smod |
]]

FAMILY CODE

36

SPECIAL PROPERTIES

  memory
read-write, binary
Access to the full 256 byte memory range. Much of this space is reserved or special use. User space is the page area.
See the DATASHEET for a full memory map.

  PIO
write-only, yes-no
Controls the PIO pin allowing external switching.
Writing "1" turns the PIO pin on (conducting). Writing "0" makes the pin non-conducting. The logical state of the voltage can be read with the sensed property. This will reflect the current voltage at the pin, not the value sent to PIO
Note also that PIO will also be altered by the power-status of the DS2670 See the datasheet for details.

  sensed
read-only, yes-no
The logical voltage at the PIO pin. Useful only if the PIO property is set to "0" (non-conducting).
Value will be 0 or 1 depending on the voltage threshold.

  vis
read-only, floating point
Current sensor reading (unknown external resistor). Measures the voltage gradient between the Vis pins. Units are in Volts
The vis readings are integrated over time to provide the volthours property.
The current reading is derived from vis assuming the internal 25 mOhm resistor is employed. There is no way to know this through software.

  vis_B
read-only, floating point
Current sensor reading (unknown external resistor). Measures the voltage gradient between the Vis pins. Units are in Volts
The vis readings are integrated over time to provide the volthours property.
The vis_B is from a different tuning of the DS2740 (3) chip with faster sampling and lower resolution. There is no way to know this through software.

  volthours
read-write, floating point
Integral of vis over time. Units are in volthours

OBSCURE PROPERTIES

  smod
read-write, yes-no
Bit flags corresponding to various battery management functions of the chip. See the DATASHEET for details of the identically named entries.
In general, writing "0" corresponds to a 0 bit value, and non-zero corresponds to a 1 bit value.
Default power-on state for the corresponding properties.

STANDARD PROPERTIES

ALARMS
None.

DESCRIPTION

  DS2740
The DS2740 (3) is a class of battery charging controllers. This chip measures voltage and volthours, and has a pin that can be used for control.

ADDRESSING

DATASHEET
http://pdfserv.maxim-ic.com/en/ds/DS2740.pdf

SEE ALSO

AVAILABILITY
http://www.owfs.org

AUTHOR
Paul Alfille (paul.alfille@gmail.com)