LTC6803 查看數據表（PDF） - Linear Technology

零件编号

产品描述 (功能)

生产厂家

LTC6803

Multicell Battery Stack Monitor

Linear Technology 

LTC6803-1/LTC6803-3

APPLICATIONS INFORMATION

+

+

21 C4

B4

+

23 C3

B3

+

25 C2 MUX

+

27 C1

29 V–

LTC6803-1

100µA

Figure 10. Open Connection

680313 F10

+

+

21 C4

B4

+

CF4

23 C3

B3

CF3

+

25 C2 MUX

+

27 C1

29 V–

LTC6803-1

100µA

680313 F11

Figure 11. Open Connection with RC Filtering

between C2 and C4 after several cycles of measuring cells

B3 and B4. Thus the measurements for B3 and B4 may

indicate a valid cell voltage when in fact the exact state of

B3 and B4 is unknown.

To reliably detect an open connection, the command

STOWAD is provided. With this command, two 100µA

current sources are connected to the ADC inputs and

turned on during all cell conversions. Referring again to

Figure 11, with the STOWAD command, the C3 pin will be

pulled down by the 100µA current source during the B3

cell measurement and during the B4 cell measurement.

This will tend to decrease the B3 measurement result and

increase the B4 measurement result relative to the normal

STCVAD command. The biggest change is observed in the

B4 measurement when C3 is open. So, the best method to

detect an open wire at input C3 is to look for an increase

28

in the value of battery connected between inputs C3 and

C4 (battery B4).

The following algorithm can be used to detect an open

connection to cell pin Cn:

1. Issue a STOWAD command (with 100µA sources

connected).

2. Issue a RDCV command and store all cell measurements

into array CELLA(n).

3. Issue the 2nd STOWAD command (with 100µA sources

connected).

4. Issue the 2nd RDCV command and store all cell mea-

surements into array CELLB(n).

5. For battery cells, if CELLA(1) < 0 or CELLB(1) < 0, V–

must be open.

If CELLA(12) < 0 or CELLB(12) < 0, C12 must be open.

For n = 2 to 11, if CELLB(n+1) – CELLA(n+1) > 200mV,

or CELLB(n+1) reaches the full scale of 5.375V, then

Cn is open.

The 200mV threshold is chosen to provide tolerance for

measurement errors. For a system with the capacitor con-

nected to Cn larger than 0.5µF, repeating step 3 several

times will discharge the external capacitor enough to meet

the criteria.

If the top C pin is open yet V+ is still connected, then the

best way to detect an open connection to the top C pin

is by comparing the sum of all cell measurements using

the STCVAD command to an auxiliary measurement of

the sum of all the cells, using a method similar to that

shown in Figure 21. A significantly lower result for the

sum of all 12 cells suggests an open connection to the

top C pin, provided it was already determined that no

other C pin is open.

USING THE S PINS AS DIGITAL OUTPUTS OR

GATE DRIVERS

The S outputs include an internal pull-up PMOS. Therefore

the S pins will behave as a digital output when loaded with

a high impedance, e.g., the gate of an external MOSFET.

For applications requiring high battery discharge currents,

connect a discrete PMOS switch device and suitable

680313f

Share Link: