Datasheet LTC2991 (Analog Devices) - 10

LTC2991
OPERATION
The LTC2991 monitors voltage, current, internal and remote Remote diode measurements are conducted using multiple temperatures. It can be configured through an I2C inter- ADC conversions and source currents to compensate for face to measure many combinations of these parameters. sensor series resistance. The V2, V4, V6 or V8 terminals of Single or repeated measurements can be configured. the LTC2991 are terminated with a diode if that channel is Remote temperature measurements use transistors as configured for temperature measurements. It is acceptable temperature sensors, allowing the remote sensor to be a to ground these pins, but increased noise may result on discrete NPN (ex. MMBT3904) or an embedded PNP device the temperature measurements. The LTC2991 is calibrated in a microprocessor or FPGA. The internal ADC reference to yield the correct temperature for a remote diode with an minimizes the number of support components required. ideality factor of 1.004. See the Applications Information The Functional Diagram displays the main functional com- section for compensation of sensor ideality factors other ponents of the device. The input signals are selected with an than the factory calibrated value of 1.004. input mux, controlled by the control logic block. The control The LTC2991 communicates through an I2C serial in- logic block uses the mode bits in the control registers to terface. The serial interface provides access to control, manage the sequence and types of data acquisition. The status and data registers. I2C defines a 2-wire open-drain control logic block also controls the current sources during interface supporting multiple slave devices and masters remote temperature acquisition. The order of acquisitions on a single bus. The LTC2991 supports 100kbit/s in the is fixed: V1, V2, V3, V4, V5, V6, V7, V8, TINTERNAL then standard mode and up to 400kbit/s in fast mode. The VCC. The ADC performs the necessary conversion(s) and eight physical addresses supported are listed in Table 1. supplies the data to the control logic for routing to the ap- The I2C interface is used to trigger single conversions, or propriate data register. The I2C interface supplies access start repeated conversions by writing to a dedicated trig- to control, status and data registers. The ADR2, ADR1 and ger register. The data registers contain a destructive read ADR0 pins select one of eight possible I2C addresses (see status bit (data valid), which is used in repeated mode to Table 1). The UVLO inhibits I2C communication below the determine if the registers contents have been previously specified threshold. During an undervoltage condition, the read. This bit is set when the register is updated with new part is in a reset state, and the data and control registers data, and cleared when read. are placed in the default state of 00h. 2991ff 10 For more information www.linear.com/LTC2991 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Timing Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts