MAX17843 datasheet(40/131 Pages) MAXIM

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Measurement Alerts

After the measurement cycle, the ALU compares the

enabled measurements to the various configured thresh-

olds, as shown in Table 12, and sets the alert bits before

the ALU data is transferred to the data registers. In over-

sampling mode, the alert status is updated after the last

oversample. The alerts are updated whether or not the

data is moved from the ALU registers to the data registers

and are only updated for those measurements enabled in

the MEASUREEN register.

Voltage Alerts

Use the ALRTOVEN and ALRTUVEN registers to enable

voltage alerts for the cell and auxiliary inputs. If a cell-

voltage alert is enabled, the cell input voltage is compared

against the programmable overvoltage and undervoltage

thresholds after every acquisition as shown in Figure 14.

Separate thresholds for both setting and clearing the alert

provide hysteresis. Configure the set thresholds for cell

undervoltage (VUVTHSET) and overvoltage (VOVTHSET)

using the UVTHSET and OVTHSET registers. Configure

the clear thresholds for cell undervoltage (VUVTHCLR)

and cell overvoltage (VOVTHCLR) using the UVTHCLR

and OVTHCLR registers.

Alert flags in the ALRTOVCELL register are set, if enabled,

when the acquired cell voltage is over VOVTHSET. Alerts

in the ALRTUVCELL register are set, if enabled, when the

acquired cell voltage is under VUVTHSET. The alerts are

cleared when the cell voltage moves in the opposite direc-

tion and crosses the clear threshold. The voltage must

cross the threshold; if it is equal to a threshold, the alert

flag does not change. Therefore, setting the overvoltage

set threshold to full scale, or setting the undervoltage set

threshold to zero scale, effectively disables voltage alerts.

The ALRTOV and ALRTUV bits in the STATUS register

are set when any alert flag is set in the ALRTOVCELL or

ALRTUVCELL registers, respectively. ALRTCELL[n] is the

logical OR of ALROVCELL[n] and ALRTUVCELL[n].

Cell Mismatch

Enable the mismatch alert to signal when the minimum

and maximum cell voltages differ by more than a specified

voltage. The MSMTCH register sets the 14-bit threshold

(VMSMTCH) for the mismatch alert (ALRTMSMTCH).

Whenever VMAX - VMIN > VMSMTCH, thenALRTMSMTCH

= 1. The alert bit is cleared when a new acquisition does

not exceed the threshold condition. To disable the alert,

write FFCH to the MSMTCH register (default value).

Cell Statistics

The cell numbers with the lowest and highest voltages

are stored in the MINMAXCELL register. When multiple

cells have the same minimum or same maximum volt-

age, only the highest cell position having that voltage is

reported. The sum of all enabled cell voltages is stored

in the TOTAL register as a 16-bit value. For acquisitions

with no enabled cell inputs, the MINMAXCELL and TOTAL

registers are not updated.

Temperature Alerts

Temperature alerts, if enabled, occur when the acquired

AUXINx input voltages fall outside the thresholds config-

ured by the AINOT and AINUT registers. Unlike the cell-

voltage alerts, the temperature thresholds do not have the

hysteresis afforded by separate set and clear thresholds.

Table 12. Measurement Alerts

DESCRIPTION

CONDITION OR RESULT

ALERT BIT

LOCATION

Cell overvoltage (OV)

VCn - VCn-1 > VVOVTHSET

ALRTOV, ALRTOVn

STATUS, ALRTOVCELL

Cell undervoltage (UV)

VCn - VCn-1 < VUVTHSET

ALRTUV, ALRTUVn

STATUS, ALRTUVCELL

Cell mismatch

VMAX - VMIN > VMSMTCH

ALRTMSMTCH

STATUS

Cell with minimum voltage

n where VCELLn = VMIN

None

MINMAXCELL

Cell with maximum voltage

n where VCELLn = VMAX

None

MINMAXCELL

Total of all cell voltages

Σ VCELLn where n = 1–12

None

TOTAL

AUXINx overvoltage

(undertemperature)

VAUXINx > VAINUT

ALTRTCOLD, ALRTOVAINx

STATUS, ALRTOVCELL

AUXINx undervoltage

(overtemperature)

VAUXINx < VAINOT

ALRTHOT, ALRTUVAINx

STATUS, ALRTUVCELL

MAX17843

12-Channel, High-Voltage Smart Sensor

Data-Acquisition Interface

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