ltc6803g-4 Linear Technology Corporation, ltc6803g-4 Datasheet - Page 37

• Manufacturer Part Number: ltc6803g-4
• Description: Ltc6803-2/ltc6803-4 - Multicell Battery Stack Monitor
• Manufacturer: Linear Technology Corporation

APPLICATIONS INFORMATION
As an example, Figure 24 shows the DC voltage on each
pin with respect to V
connected to the LTC6803.
ADVANTAGES OF DELTA-SIGMA ADCS
The LTC6803 employs a delta-sigma analog-to-digital
converter for voltage measurement. The architecture of
delta-sigma converters can vary considerably, but the
common characteristic is that the input is sampled many
times over the course of a conversion and then filtered or
averaged to produce the digital output code. In contrast,
a SAR converter takes a single snapshot of the input
voltage and then performs the conversion on this single
sample. For measurements in a noisy environment, a
delta-sigma converter provides distinct advantages over
a SAR converter.
–
when twelve 3.6V battery cells are
Figure 24. Typical Pin Voltages for Twelve 3.6V Cells
43.2V
43.2V
43.2V
39.6V
39.6V
32.4V
32.4V
28.8V
28.8V
25.2V
25.2V
14.4V
14.4V
21.6
21.6
10.8
10.8
36V
36V
18V
18V
7.2
V
C12
S12
C11
S11
C10
S10
C9
S9
C8
S8
C7
S7
C6
S6
C5
S5
C4
S4
C3
S3
C2
+
LTC6803-4
While SAR converters can have high sample rates, the full-
power bandwidth of a SAR converter is often greater than
1MHz, which means the converter is sensitive to noise out
to this frequency. And many SAR converters have much
higher bandwidths—up to 50MHz and beyond. It is pos-
sible to filter the input, but if the converter is multiplexed
to measure several input channels a separate filter will be
required for each channel. A low frequency filter cannot
reside between a multiplexer and an ADC and achieve a
high scan rate across multiple channels. Another conse-
quence of filtering a SAR ADC is that any noise reduction
gained by filtering the input cancels the benefit of having
a high sample rate in the first place, since the filter will
take many conversion cycles to settle.
V
V
GPIO2
GPIO1
WDTB
TEMP2
TEMP1
680324 F24
V
CSBI
SCKI
V
SDO
TOS
REG
SDI
REF
NC
A3
A2
A1
A0
C0
S1
C1
S2
V
–
0V TO 5.5V
0V TO 5.5V
0V TO 5.5V
0V TO 5.5V
0V TO 5.5V
0V TO 5.5V
0V TO 5.5V
0V TO 5.5V
0V TO 5.5V
0V TO 5.5V
0V TO 5.5V
0V TO 5.5V
5V
3.1V
1.5V
1.5V
0V
0V
0V
3.6V
3.6V
7.2V
LTC6803-2/LTC6803-4
37
680324f