Electronic Components Datasheet Search |
|
SX8744EMSTRT Datasheet(PDF) 11 Page - Semtech Corporation |
|
SX8744EMSTRT Datasheet(HTML) 11 Page - Semtech Corporation |
11 / 24 page ACS Revision 2.91/February 2010 ©2010 Semtech Corp. SX8733/SX8743/SX8744 www.semtech.com Page 11 Digital temperature sensor ADVANCED COMMUNICATIONS & SENSING DATASHEET Track resistances up to 1 kOhm may be cancelled. It is important that the track resistance values in the cathode or anode path of the external sensor are made equal. Care must be taken during PCB layout to match track resistances between the device and the sensor. Any resistance difference will lead to cancellation errors. In this mode, VSS is used for the current return path from the cathode. This connection must be placed close to the diode’s cathode. One port supply the current modulation to the anode and another port supply the cancellation current to the cathode. The resulting junction voltage modulation is measured between the 2 used ports. Figure 5 explains the method: Assume sensor Q1 is being measured in mode 2 with 3-point track resistance cancellation enabled. The PCB trace linking the device to the external sensor must be matched which means the PCB track resistance are the same. The same current is forced out of P1 and P2. The voltages developed on P1 and P2 traces are the same therefore the differential voltage seen on P1-P2 is not impacted by the track resistance. Figure 5. 3-Point Track Resistance Cancellation 3.5.3. The Kelvin (4-wire) Track Resistance Cancellation The sensor is connected to the chip via 4 wires. Two comes from the current source (force : P3, P4) and two are used for the voltage measurement (sense : P1, P2). The Kelvin connection avoids the measurement error caused by the voltage drop in the force path. Sense leads are attached directly accross the external sensor. The P1 and P2 connections must be as close as possible to sensor anode and cathode respectively. Figure 6. Kelvin (4-wire) Track Resistance Cancellation 3.6. Temperature Acquisition Sequence The SX8743 monitors up to 4 sensors (3 remote and 1 internal). Theses can be scanned in sequence to make an automatic reading of the sensors one after the other. The result of each conversion is stored in the temperature registers (see Table 6). The register RegSensor defines which sensors are scanned in the sequence. When all the sensors are selected, the sequence is the following: Int → Ext1→ Ext2→ Ext3→Int→etc. P1 P2 VSS V1 V2 I I 2I V1 P1 P2 P3 P4 I Force (+) Force (-) Sense (-) I Sense (+) |
Similar Part No. - SX8744EMSTRT |
|
Similar Description - SX8744EMSTRT |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |