Electronic Components Datasheet Search |
|
LT1113AMJ8 Datasheet(PDF) 10 Page - Linear Technology |
|
LT1113AMJ8 Datasheet(HTML) 10 Page - Linear Technology |
10 / 16 page 10 LT1113 S APPLICATI I FOR ATIO The gain therefore is 1 + CF/CS. For unity gain, CF should equal the transducer capacitance plus the input capaci- tance of the LT1113 and RF should equal RS. In the noninverting mode example, the transducer current is converted to a change in voltage by the transducer capaci- tance; this voltage is then buffered by the LT1113 with a gain of 1 + R1/R2. A DC path is provided by RS, which is either the transducer impedance or an external resistor. Since RS is usually several orders of magnitude greater than the parallel combination of R1 and R2, RB is added to balance the DC offset caused by the noninverting input bias current and RS. The input bias currents, although small at room temperature, can create significant errors over increasing temperature, especially with transducer resistances of up to 100M or more. The optimum value for RB is determined by equating the thermal noise (4kTRS) to the current noise (2qIB) times RS2. Solving for RS results in RB = RS = 2VT/IB V kT q mV at C T == ° 26 25 . A parallel capacitor, CB, is used to cancel the phase shift caused by the op amp input capacitance and RB. Reduced Power Supply Operation The LT1113 can be operated from ±5V supplies for lower power dissipation resulting in lower IB and noise at the expense of reduced dynamic range. To illustrate this benefit, let’s look at the following example: An LT1113CS8 operates at an ambient temperature of 25 °C with ±15V supplies, dissipating 318mW of power (typical supply current = 10.6mA for the dual). The SO-8 package has a θJA of 190°C/W, which results in a die temperature increase of 60.4 °C or a room temperature die operating temperature of 85.4 °C. At ±5V supplies, the die temperature increases by only one third of the previous amount or 20.1 °C resulting in a typical die operating temperature of only 45.1 °C. A 40 degree reduction of die temperature is achieved at the expense of a 20V reduction in dynamic range. If no DC correction resistor is used at the input, the input referred offset will be the input bias current at the operating die temperature times the trans- ducer resistance (refer to Input Bias and Offset Currents vs Chip Temperature graph in Typical Performance Charac- teristics section). A 100mV input VOS is the result of a 1nA IB (at 85°C) dropped across a 100M transducer resis- tance; at ±5V supplies, the input offset is only 28mV (IB at 45 °C is 280pA). Careful selection of a DC correction R2 OUTPUT RB CB R1 CS RS CB ≅ CS RB = RS RS > R1 OR R2 TRANSDUCER OUTPUT CF CB RB CB = CFCS RB = RFRS RF CS RS TRANSDUCER 1113 • F02 Q = CV; dQ dt = I = C dV dt Figure 2. Noninverting and Inverting Gain Configurations |
Similar Part No. - LT1113AMJ8 |
|
Similar Description - LT1113AMJ8 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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 |