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LMP8358

www.ti.com

SNOSB09B –APRIL 2010–REVISED MARCH 2013

LMP8358 Zero-Drift, Programmable Instrumentation Amplifier with Diagnostics

Check for Samples: LMP8358

FEATURES

DESCRIPTION

The LMP8358 is a precision programmable-gain

Typical Values Unless Otherwise Noted, T

instrumentation amplifier in TI's LMP™ precision

25°C

amplifier family. Its gain can be programmed to 10,

• Supply Voltage 2.7V to 5.5V

20, 50, 100, 200, 500, or 1000 through an SPI-

• Supply Current 1.8 mA

compatible serial interface or through a parallel

interface. Alternatively, its gain can be set to an

• Max Gain Error 0.15%

arbitrary value using two external resistors. The

• Max Gain Drift 16 ppm/°C

LMP8358 uses patented techniques to measure and

• Min CMRR 110 dB

continuously correct its input offset voltage,

eliminating offset drift over time and temperature and

• Max Offset Voltage 10 µV

the effect of 1/f noise. Its ground-sensing CMOS input

• Max Offset Voltage Drift 50 nV/°C

features a high CMRR and low input bias currents. It

• GBW (Gain = 10) 8 MHz

is capable of sensing differential input voltages in a

common-mode range that extends from 100mV below

• Max Non-Linearity 100 ppm

the negative supply to 1.4V below the positive supply,

• Operating Temperature Range −40°C to 125°C

making it an ideal solution for interfacing with ground-

• Input Fault Detection

referenced sensors, supply-referenced sensor

bridges, and any other application requiring precision

• SPI or Pin Configurable Modes

and long-term stability. Additionally, the LMP8358

• EMIRR at 1.8GHz 92 dB

includes fault detection circuitry to detect open and

• 14-Pin SOIC and 14-Pin TSSOP Package

shorted inputs and deteriorating connections to the

signal source. Other features that make the LMP8358

APPLICATIONS

a versatile solution for many applications are its rail-

to-rail output, low input voltage noise and high gain-

• Bridge Sensor Amplifier

bandwidth product.

• Thermopile Amplifier

• Portable Instrumentation

• Medical Instrumentation

• Precision Low-side Current Sensing

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2LMP is a trademark of Texas Instruments.

3All other trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (40 pages)

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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 LMP8358 Zero-Drift, Programmable Instrumentation Amplifier with Diagnostics Check for Samples: LMP8358 FEATURES 1 Typical Values Unless Otherwise Noted, TA = 25°C 23 • • • • • • • • • • • • • • Supply Voltage 2.7V to 5.5V Supply Current 1.8 mA Max Gain Error 0.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com Typical Application +5V 0.1 PF 10 PF + EMI R1 + V +IN R4 1 7 OUT 6 -IN R2 2 R3 5 VHSER/VLPAR +3.3V 8 4 VLSER/VHPAR 10 VBRIDGE 3 FB REFF VREF REFS LMP8358 SDI/G1 MICRO CONTROLLER SCK/G2 CSB/SHDN 14 13 SDO/G0 To Next SPI Device 12 11 9 - V These devices have limited built-in ESD protection.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 Operating Ratings (1) −40°C to 125°C Temperature Range Supply Voltage (VS = V+ – V−) 2.7V to 5.5V VIN Differential (V+IN − V−IN) Package Thermal Resistance (θJA (2)) (1) (2) ±100mV 14-Pin SOIC 145°C/W 14-Pin TSSOP 135°C/W Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com 3.3V Electrical Characteristics (continued) Unless otherwise specified, all limits are ensured for TA = 25°C. V+ = 3.3V , V− = 0V, VREF = V+/2, VCM = V+/2, RL = 10 kΩ to VREF, CL = 10 pF; Serial Control Register: G[2:0] = 110b (Gain = 1000x), COMP[2:0] = 000b, MUX[1:0] = 00b, POL, SHDN, FILT, PIN = 0b, CUR[2:0] = 000b. Boldface limits apply at the temperature extremes.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 3.3V Electrical Characteristics (continued) Unless otherwise specified, all limits are ensured for TA = 25°C. V+ = 3.3V , V− = 0V, VREF = V+/2, VCM = V+/2, RL = 10 kΩ to VREF, CL = 10 pF; Serial Control Register: G[2:0] = 110b (Gain = 1000x), COMP[2:0] = 000b, MUX[1:0] = 00b, POL, SHDN, FILT, PIN = 0b, CUR[2:0] = 000b. Boldface limits apply at the temperature extremes. Symbol Parameter Min (1) Conditions Typ (2) Max (1) ts 0.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com 5.0V Electrical Characteristics (continued) Unless otherwise specified, all limits are ensured for TA = 25°C. V+ = 5.0V , V− = 0V, VREF = V+/2, VCM = V+/2, RL = 10 kΩ to VREF, CL = 10 pF; Serial Control Register: G[2:0] = 110b (Gain = 1000x), COMP[2:0] = 000b, MUX[1:0] = 00b, POL, SHDN, FILT, PIN = 0b, CUR[2:0] = 000b. Boldface limits apply at the temperature extremes. Min (1) Typ (2) V − 0.1V ≤ VCM ≤ V − 1.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 5.0V Electrical Characteristics (continued) Unless otherwise specified, all limits are ensured for TA = 25°C. V+ = 5.0V , V− = 0V, VREF = V+/2, VCM = V+/2, RL = 10 kΩ to VREF, CL = 10 pF; Serial Control Register: G[2:0] = 110b (Gain = 1000x), COMP[2:0] = 000b, MUX[1:0] = 00b, POL, SHDN, FILT, PIN = 0b, CUR[2:0] = 000b. Boldface limits apply at the temperature extremes.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com 5.0V Electrical Characteristics (continued) Unless otherwise specified, all limits are ensured for TA = 25°C. V+ = 5.0V , V− = 0V, VREF = V+/2, VCM = V+/2, RL = 10 kΩ to VREF, CL = 10 pF; Serial Control Register: G[2:0] = 110b (Gain = 1000x), COMP[2:0] = 000b, MUX[1:0] = 00b, POL, SHDN, FILT, PIN = 0b, CUR[2:0] = 000b. Boldface limits apply at the temperature extremes.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 Connection Diagram +IN -IN REFS REFF FB OUT V + 1 14 2 13 3 12 4 11 5 10 6 9 7 8 SDO/G0 SDI/G1 SCK/G2 CSB/SHDN VLSER/VHPAR - V VHSER/VLPAR Figure 1.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com Block Diagram + V 7 +IN 1 -IN 2 COMP[2:0] Diff In + Zero/Cal 1/50 +IN/50 1/50 -IN/50 V - PIN + gm - OUTPUT AMP + FB 4 REFF 3 REFS S2 + SH DN 0] [ 2: MP O C PIN gm CU 2: 0 R[ ] S1 GAIN SET - T FIL G[2:0] VLSER/VHPAR 10 VHSER/VLPAR 5 POL MUX[1:0] FAULT DETECTION :0] ] X[1 OL 2:0 G[ P MU OUT FILT CUR[2:0] V 6 CONTROL INTERFACE 8 14 SDO/G0 13 SDI/G1 12 SCK/G2 11 CSB/SHDN 9 - V Figure 2.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 Timing Diagrams SCK t11 t3 t2 t1 t4 t5 t7 t11 CSB SDI D15 t9 SDO t8 D14 D0 t6 t10 OLD D15 OLD D1 OLD D0 Figure 3. SPI Timing Diagram IOL 200 PA + TO PIN V /2 CL 10 pF IOH 200 PA Figure 4.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics V+ = 3.3V and TA = 25°C unless otherwise noted. Gain vs. Frequency for Various COMP Settings Gain vs. Frequency for Various COMP Settings 30 50 20 40 COMP = 000 10 GAIN (dB) GAIN (dB) COMP = 000 COMP = 100 0 COMP = 001 30 COMP = 010 COMP = 100 20 -10 GAIN = 10 GAIN = 100 + + V = +2.5V V = +2.5V - - V = -2.5V -20 100 V = -2.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 Typical Performance Characteristics (continued) + V = 3.3V and TA = 25°C unless otherwise noted. Gain Error vs. Common Mode Voltage, VS = 3.3V Gain Error Distribution, Gain = 10, VS = 3.3V 25 0.03 SAMPLE SIZE = 10000 GAIN = 10 RELATIVE FREQUENCY (%) GAIN ERROR (%) + V = +1.65V 0.02 0.01 0 -0.01 GAIN = 100 -0.02 GAIN = 10 + - 20 V = -1.65V 15 10 5 V = +3.3V - -0.03 -0.5 V = 0V 0.0 0.5 1.0 1.5 0 -0.1 2.0 -0.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics (continued) + V = 3.3V and TA = 25°C unless otherwise noted. TCVOS Distribution, VS = 3.3V SAMPLE SIZE = 8400 TCVOS Distribution, VS = 5V SAMPLE SIZE = 8400 Gain = 1000 Gain = 1000 + V = +2.5V + - 40 35 30 25 20 15 10 5 0 V = -1.65V -0.02 -0.01 0 0.01 RELATIVE FREQUENCY (%) RELATIVE FREQUENCY (%) V = +1.65V - 40 35 30 25 20 15 10 5 0 V = -2.5V -0.02 0.02 -0.01 Figure 18. VOS vs.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 Typical Performance Characteristics (continued) + V = 3.3V and TA = 25°C unless otherwise noted. VOS vs. VREF, VS = 3.3V CMRR vs. Frequency 140 -40°C 0 120 -0.3 GAIN = 10 + CMR (dB) VOS (PV) V = +1.65V - -0.6 V = -1.65V 25°C 100 80 -0.9 125°C 60 GAIN = 1000 + -1.2 V = +2.5V - -1.9 -1.5 -1.1 -0.7 -0.3 0.1 40 0.5 V = -2.5V 10 100 1k Figure 23. Figure 24. CMRR vs. Frequency PSRR vs.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics (continued) + V = 3.3V and TA = 25°C unless otherwise noted. Small Signal Step Response for Various COMP Settings Small Signal Step Response for Various COMP Settings COMP = 011 GAIN = 1000 + V = +2.5V - V = -2.5V 20 mV/DIV 20 mV/DIV COMP = 010 COMP = 001 COMP = 000 COMP = 100 COMP = 100 COMP = 011 COMP = 000 COMP = 001 COMP = 010 GAIN = 1000 + V = +2.5V - V = -2.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 Typical Performance Characteristics (continued) + V = 3.3V and TA = 25°C unless otherwise noted. Input Bias Current vs. VCM, VS = 3.3V 1.0 Input Bias Current vs. VCM, VS = 5.0V 1.0 0.5 0.5 0 IB (nA) IB (nA) 25°C 25°C 0 -40°C -0.5 -40°C -0.5 -1.0 -1.0 -1.5 -1.5 + -2.0 + V = +2.5V V = +1.65V -1.5 -1.1 -0.7 -0.3 0.1 - V = -2.5V 125°C - V = -1.65V 125°C -2.0 -1.9 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 0.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics (continued) + V = 3.3V and TA = 25°C unless otherwise noted. ITEST3 vs. VCM ITEST4 vs. VCM 1.10 10.40 CUR[2:0] = 011b CUR[2:0] = 100b + + V = +2.5V 1.08 10.38 V = -2.5V ITEST (PA) ITEST (PA) V = +2.5V - 1.06 -40°C 1.04 1.02 - V = -2.5V 25°C 10.36 -40°C 10.34 10.32 25°C 125°C 125°C 10.30 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 1.00 -3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 APPLICATION INFORMATION INTRODUCTION The LMP8358 is a precision programmable gain instrumentation amplifier. Its gain can be programmed to 10, 20, 50, 100, 200, 500 or 1000 through an SPI-compatible serial interface or through a parallel interface. Alternatively, its gain can be set to an arbitrary value using external resistors. Note that at low gains the dynamic range is limited by the maximum input differential voltage of ±100mV.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com LMP8358 G0..G2 SHDN CONTROLLER LMP8358 G0..G2 SHDN LMP8358 G0..G2 SHDN Figure 47. (A) Communication with LMP8358 in Parallel Mode LMP8358 LMP8358 LMP8358 MISO SCK SCK SCK SCK CONTROLLER MOSI SDO SDI CSB SDO SDI CSB SDO SDI CSB CSB Figure 48. (B) Communication with LMP8358 in Serial Mode Communication Mode Selection The interface mode is determined by the two interface level pins VLSER/VHPAR and VHSER/VLPAR.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 V+ VLSER/VHPAR LOGIC I/O LEVELS VHSER/VLPAR VSERIAL MODE PARALLEL MODE Figure 49. Communication Mode Selection. PARALLEL CONTROL INTERFACE MODE The LMP8358 is put into Parallel Mode by setting VLSER/VHPAR > VHSER/VLPAR. The register in the LMP8358 does not control the settings of the LMP8358 in this mode.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com Table 3. Function of Digital IO Pins, Serial Mode Pin Name Description SDO Serial Data Out SDI Serial Data In SCK Serial Clock CSB Chip Select VLSER Negative Logic level VHSER Positive Logic Level Table 4.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 MOSI LMP8358 LMP8358 LMP8358 SCK SDI SCK SDI SCK SDI SCK CONTROLLER SDO SDO CSB SDO CSB CSB CSB Figure 50. Star Configuration for Writing the Same Value Into Each Register MOSI LMP8358 LMP8358 LMP8358 SCK SDI SCK SDI SCK SDI SCK CONTROLLER SDO SDO SDO CSB1 CSB CSB2 CSB CSB CSB3 Figure 51.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com Table 5. If all three LMP8358s need a gain of 100 with a compensation level of 010.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 VOUT OUT CFILTER R1 Z1 R2 Z2 FB REFS VREF REFF Figure 53. External Gain Set Resistors and Filter Capacitor Frequency Compensation (Serial) The gain-bandwidth compensation is set to one of five levels under program control. The amount of compensation can be decreased to maximize the available bandwidth as the gain of the amplifier is increased.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com Table 9.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 Shutdown Enable (Serial, Parallel) When the SHDN bit of the LMP8358 register is set to 1b the part is put into shutdown mode. It will use less than 1μA in this state. Table 11. Shutdown (Register bit 9) SHDN Mode 0 Active mode 1 Shutdown mode Filter and External Filter Capacitor (Serial) The FILT bit controls the state of switch S2 shown in the Block Diagram.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com The Fault Detection Current bit, CUR[2:0] controls the amount of current that sent to the input pin as shown in Table 15. Table 15.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 Open Input Figure 56 shows an example of an open input fault. To sense this type of fault use the 1/50 feature by setting MUX[1:0] to 10b to test the +IN pin or to 11b to test the −IN pin, POL to 0b, PIN to 1b to test the −IN pin, and G[2:0] to 010b for a gain of 50, and inject 100µA current by setting CUR[2:0] = 101b (5082x or 58C2x). Since the input is open the input pin will be pulled to V+.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com Degraded Input Line Figure 59 shows an example of a degraded connection between the bridge and the +IN pin of the LMP8358. This fault is shown by the 1 kΩ resistor placed between the bridge and the LMP8358. To detect this fault use the 1/50 feature by setting MUX[1:0] to 10b to test the +IN pin, POL to 0b, and G[2:0] to 010b for a gain of 50. This will give an overall gain of 1.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 Table 16. Fault Detection Matrix (continued) 58 C2x 2.55V 2.65V* Degraded −IN line * The values shown for a degraded input line will vary depending on the resistance in the line. This table uses the value in Figure 59 and Figure 60, 1kΩ. START UP AND POWER ON RESET During power on, 50µs after V+ − V− > 1V the LMP8358 resets the internal register to 0000x.
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LMP8358 SNOSB09B – APRIL 2010 – REVISED MARCH 2013 www.ti.com negative input of the ADC and the REFF and REFS pins of the LMP8358 can be set to +2.5V to set the signal at the center of the supply. A resistor divider supplies +2.5V to the positive input of an LMP7701 set up in a buffer configuration. The LMP7701 acts as a low impedance source for the REFF pin. The VIOand VHSER/VLPAR pins should all be set to the same voltage as the microcontroller, +3.3V in this example.
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LMP8358 www.ti.com SNOSB09B – APRIL 2010 – REVISED MARCH 2013 REVISION HISTORY Changes from Revision A (March 2013) to Revision B • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LMP8358MAX/NOPB SOIC D 14 2500 330.0 16.4 6.5 9.35 2.3 8.0 16.0 Q1 LMP8358MTX/NOPB TSSOP PW 14 2500 330.0 12.4 6.95 8.3 1.6 8.0 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LMP8358MAX/NOPB SOIC D 14 2500 367.0 367.0 35.0 LMP8358MTX/NOPB TSSOP PW 14 2500 367.0 367.0 35.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.