LTC6802IG-1#PBF Linear Technology, LTC6802IG-1#PBF Datasheet - Page 19

• Manufacturer Part Number: LTC6802IG-1#PBF
• Description: IC MONITOR BATT STACK MC 44-SSOP
• Manufacturer: Linear Technology

Specifications of LTC6802IG-1#PBF

• Function: Battery Monitor
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 4 V ~ 50 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 44-SOP (0.200", 5.30mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
Table 1. Monitor Mode Cell Selection
If MMB is low then brought high, all device configuration
values are reset to the default states including the VUV,
VOV, and CDC configuration bits.
SERIAL PORT
Overview
The LTC6802-1 has an SPI bus compatible serial port.
Several devices can be daisy chained in series.
There are two sets of serial port pins, designated as low
side and high side. The low side and high side ports enable
devices to be daisy chained even when they operate at dif-
ferent power supply potentials. In a typical configuration,
the positive power supply of the first, bottom device is
connected to the negative power supply of the second, top
device, as shown in Figure 1. When devices are stacked in
this manner, they can be daisy chained by connecting the
high side port of the bottom device to the low side port of
the top device. With this arrangement, the master writes to
or reads from the cascaded devices as if they formed one
long shift register. The LTC6802-1 translates the voltage
level of the signals between the low side and high side
ports to pass data up and down the battery stack.
Physical Layer
On the LTC6802-1, seven pins comprise the low side and
high side ports. The low side pins are CSBI, SCKI, SDI,
and SDO. The high side pins are CSBO, SCKO and SDOI.
CSBI and SCKI are always inputs, driven by the master
or by the next lower device in a stack. CSBO and SCKO
WDTB
0
0
0
0
1
1
1
1
GPIO2
0
0
1
1
0
0
1
1
GPIO1
0
1
0
1
0
1
0
1
CELL INPUTS MONITORED
Cells 1 to 10
Cells 1 to 11
Cells 1 to 12
Cells 1 to 5
Cells 1 to 6
Cells 1 to 7
Cells 1 to 8
Cells 1 to 9
are always outputs that can drive the next higher device
in a stack. SDI is a data input when writing to a stack of
devices. For devices not at the bottom of a stack, SDI is a
data output when reading from the stack. SDOI is a data
output when writing to and a data input when reading from
a stack of devices. SDO is an open drain output that is only
used on the bottom device of a stack, where it may be tied
with SDI, if desired, to form a single, bi-directional port.
The SDO pin on the bottom device of a stack requires a
pull-up resistor. For devices up in the stack, SDO should
be tied to the local V
To communicate between daisy-chained devices, the
high side port pins of a lower device (CSBO, SCKO, and
SDOI) must be connected through PN junction diodes to
the respective low side port pins of the next higher device
(CSBI, SCKI, and SDI). In this configuration, the devices
communicate using current rather than voltage. To signal
a logic high from the lower device to the higher device,
the lower device sinks a smaller current from the higher
device pin. To signal a logic low, the lower device sinks
a larger current. Likewise, to signal a logic high from
the higher device to the lower device, the higher device
sources a larger current to the lower device pin. To signal
a logic low, the higher device sources a smaller current.
See Figure 7.
Standby current consumed in the current mode serial inter-
face is minimized when CSBI, SCKI, and SDI are all high.
WRITE
(WRITE)
V
SENSE
+
–
Figure 7. Current Mode Interface
–
or left floating.
ON HIGHER DEVICE
ON LOWER DEVICE
HIGH SIDE PORT
LOW SIDE PORT
READ 1
LTC6802-1
(READ)
V
SENSE
+
–
68021 F07
19
68021fa