LTC6803HG-2#TRPBF-ES Linear Technology, LTC6803HG-2#TRPBF-ES Datasheet - Page 34

• Manufacturer Part Number: LTC6803HG-2#TRPBF-ES
• Description: SC-Special Function, Battery Stack Monitor, Addressable SPI
• Manufacturer: Linear Technology
• Type: Battery Monitoringr

Specifications of LTC6803HG-2#TRPBF-ES

• Battery Type: Li-Ion
• Operating Supply Voltage (min): 4V
• Operating Temp Range: -40C to 125C
• Package Type: SSOP
• Mounting: Surface Mount
• Pin Count: 44
• Operating Temperature Classification: Automotive
• Lead Free Status / Rohs Status: Compliant

LTC6803-2/LTC6803-4
APPLICATIONS INFORMATION
the resistive loading on the cell group when the IC enters
standby mode (i.e., when WDTB goes low). An LT6004
micropower operational amplifier section is shown for
buffering the divider signal to preserve accuracy. This
circuit has the virtue that it can be converted about four
times more frequently than the entire battery array, thus
offering a higher sample rate option at the expense of
some precision/accuracy, reserving the high resolution
cell readings for calibration and balancing data.
34
SPI_MASTEROUT
SPI_CHIPSELECT
CELLGROUP
CELLGROUP
Figure 19. Using a V
SPI_MASTERIN
SPI_CLOCK
GND_HOST
V
5V_HOST
WDTB
TEMP1
V
REG
V
+
–
–
470pF
20.0k
10.0k
1
100
100
1
2
3
4
TEMP
499k
IN1
GND1
IN2
GND2
1M
LTC1693-2
100
100
1/2 LT6004
1µF
Input for Full-Stack Readings
8
4
OUT1
OUT2
V
V
CC1
CC2
+
–
1µF
8
7
6
5
Figure 20. Providing an Isolated High Speed Data Interface
3
2
2N7002K
1
2
3
4
5
6
7
8
1µF
33nF
QUAD ISOLATOR
V
GND1
A1
A2
A3
A4
EN1
GND1
Si8441AB-C-IS
2
DD1
680324 F19
10nF
1
3
PE-68386
GND2
GND2
1
3
31.6k
V
•
EN2
DD2
B1
B2
B3
B4
•
6
4
16
15
14
13
12
11
10
9
BAT54S
12
PROVIDING HIGH SPEED ISOLATION OF THE SPI DATA
PORT
Isolation techniques that are capable of supporting the
1Mbps data rate of the LTC6803-2/LTC6803-4 require more
power on the isolated (battery) side than can be furnished
by the V
battery drain minimal, this means that a DC/DC function
must be implemented along with a suitable data isolation
circuit, such as shown in Figure 20. A quad (3 + 1) data
isolator Si8441AB-C-IS is used to provide non-galvanic
SPI signal connections between a host microprocessor
and an LTC6803-2/LTC6803-4. An inexpensive isolated DC/
DC converter provides powering of the isolator function
completely from the host 5V power supply. A quad three-
state buffer is used to allow SPI inputs at the LTC6803-2/
LTC6803-4 to rise to a logic high level when the isolator
circuitry powers down, assuring the lowest power con-
sumption in the standby condition. The pull-ups to V
are selected to match the internal loading on V
operating with a current mode SPI interface, thus balanc-
ing the current in all cells during operation. The additional
pull-up on the SDO line (1k resistor and Schottky diode)
is to improve rise time, in lower data rate applications this
may not be needed.
1µF
13
1/4 74ABT126
11
REG
output of the LTC6803-2/LTC6803-4. To keep
1/4 74ABT126
2
74ABT126 SUPPLY SHARED WITH
1
ISOLATOR V
3
1/4 74ABT126
CMDSH2-3
5
4
DD2
6
1/4 74ABT126
and GND2
1k
8
10
9
4.22k
4.22k
4.22k
4.22k
680324 F20
REG
V
SCKI
CSB1
SCI
SDO
V
REG
–
by ICs
680324f
REG