DS2437S Maxim Integrated Products, DS2437S Datasheet - Page 5

• Manufacturer Part Number: DS2437S
• Description: IC MONITOR SMART BATTERY 16-SSOP
• Manufacturer: Maxim Integrated Products

Specifications of DS2437S

• Function: Battery Monitor
• Battery Type: Smart Batteries
• Voltage - Supply: 2.7 V ~ 10 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Voltage is expressed in this register in scaled binary format, as outlined in Table 2. Note that while codes
exist for values below 2.7V, accuracy of the ADC and the limitation on the DS2437’s supply voltage
make it unlikely that these values would be used in actual practice. See “Memory Map” section for the
VOLTAGE REGISTER address location.
Voltage/Data Relationships Table 2
For applications requiring a general purpose voltage A/D converter, the DS2437 can be configured so that
the result of a Convert V command will place the scaled binary representation of the voltage on the V
input (as opposed to the V
Table 2. Depending upon the state of the configuration register, either (but not both) the V
voltage will be stored in the VOLTAGE REGISTER upon receipt of the Convert V command. Refer to
the description of the Configuration Register in the Memory Map section for details. If the V
used as the voltage input, the A/D will be accurate for 0V < V
5.0V. Recall that the battery voltage A/D (V
feature gives the user the ability to have a voltage A/D that meets spec accuracy for inputs over the entire
range of 0V < V
OPERATION – MEASURING BATTERY CURRENT
The DS2437 features a sigma-delta A/D converter that effectively measures the current flow into and out
of the battery pack. It does so in the background at a rate of 32 measurements/sec; thus, no command is
required to initiate current flow measurements. However, the DS2437 will only perform current A/D
measurements if the IAD bit is set to 1 in the CONFIGURATION REGISTER. The DS2437 measures
current flow in and out of the battery through the VSENS pins; the voltage from the VSENS+ pin to the
VSENS- pin is considered to be the voltage across the current sense resistor, R
terminal may be tied directly to the cell side of the R
filter between the other side of R
capacitor (C
per second, or once every 31.25 ms. This filter will capture the effect of many current spikes and will thus
allow the current accumulators to accurately reflect the total charge which has gone into or out of the
battery.
VOLTAGE
BATTERY
0.01V
9.99V
3.6V
7.2V
10V
2.7
5V
F
), the filter cutoff is approximately 32 Hz. The current A/D measures at a rate of 32 times
AD
< 10V for V
DD
input) into the VOLTAGE REGISTER in the same format described in
DIGITAL OUTPUT (Binary)
DD
= 5.0V.
SENS
0000 0000 0000 0001
0000 0001 0000 1110
0000 0001 0110 1000
0000 0001 1111 0100
0000 0010 1101 0000
0000 0011 1110 0111
0000 0011 1110 1000
and VSENS-. Using a 47 kΩ=(max) resistor (R
DD
input) loses accuracy as V
SENS
5 of 31
resistor, we recommend using an RC low pass
AD
< 2V
DD
DIGITAL OUTPUT (Hex)
over the range 2.7V < V
DD
SENS
falls below 2.7V. This
02D0h
. While the VSENS+
010Eh
01F4h
03E7h
03E8h
0001h
0168h
F
) and a 0.1 µF
DD
AD
input is
or V
DS2437
DD
AD
AD
<