LT1468

LTC2753 Dual Current Output 12-/14-/16-Bit SoftSpan DACs with Parallel I/O FEATURES ■ DESCRIPTION The LTC®2753 is a family of dual 12-, 14-, and 16-bit multiplying parallel-input, current-output DACs. These DACs operate from a single 2.7V to 5.5V supply and are all guaranteed monotonic over temperature. The LTC2753A-16 provides 16-bit performance (±1LSB INL and DNL) over temperature without any adjustments. These SoftSpan™ DACs offer six output ranges—two unipolar and four bipolar—that can be programmed through the parallel interface, or pinstrapped for operation in a single range. The LTC2753 DACs use a bidirectional input/output parallel interface that allows readback of any on-chip register. A power-on reset circuit resets the DAC outputs to 0V when power is initially applied. A logic low on the CLR pin asynchronously clears the DACs to 0V in any output range. The parts are specified over commercial and industrial temperature ranges. , LT LTC and LTM are registered trademarks of Linear Technology Corporation. , SoftSpan is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Six Programmable Output Ranges Unipolar: 0V to 5V, 0V to 10V Bipolar: ±5V, ±10V, ±2.5V, –2.5V to 7.5V Maximum 16-Bit INL Error: ±1 LSB over Temperature Low 1μA (Maximum) Supply Current Guaranteed Monotonic over Temperature Low Glitch Impulse 1nV•s 2.7V to 5.5V Single Supply Operation 2μs Settling Time to ±1 LSB Parallel Interface with Readback of All Registers Asynchronous CLR Pin Clears DAC Outputs to 0V in Any Output Range Power-On Reset to 0V 48-Pin 7mm × 7mm QFN Package APPLICATIONS ■ ■ ■ ■ High Resolution Offset and Gain Adjustment Process Control and Industrial Automation Automatic Test Equipment Data Acquisition Systems TYPICAL APPLICATION Dual 16-Bit VOUT DAC with Software-Selectable Ranges VREF 5V ROFSA 47 RIN 2 LTC2753-16 46 RFBA 15pF 45 IOUT1A DAC A R2 REFA 48 REFB 39 4 IOUT2A 44 RVOSA 43 RVOSB LTC2753-16 Integral Nonlinearity (INL) 1.0 VDD = 5V 0.8 VREF = 5V ±10V RANGE 0.6 + 1/2 LT1469 R1 RCOM 1 – 150pF INL (LSB) DAC B 42 IOUT1B ROFSB 40 SPAN I/O DATA I/O 3 16 I/O PORT I/O PORT 15pF 41 RFBB – + 32 IOUT2B + 1/2 LT1469 VOUTB 2753 TA01 – 1/2 LT1469 VOUTA 0.4 0.2 0.0 –0.2 –0.4 –0.6 –0.8 –1.0 0 16384 32768 CODE 49152 25°C 90°C –45°C 65535 2753 TA01b 2753f 1 LTC2753 ABSOLUTE MAXIMUM RATINGS (Notes 1, 2) IOUT1X, IOUT2X, RCOM to GND .................................±0.3V RVOSX, RFBX, ROFSX, RIN, REFX to GND ...................±15V VDD to GND .................................................. –0.3V to 7V Digital Inputs and Digital I/O to GND ..........................–0.3V to VDD+0.3V (max 7V) Operating Temperature Range LTC2753C..................................................... 0°C to 70°C LTC2753I .................................................. –40°C to 85°C Maximum Junction Temperature........................... 125°C Storage Temperature Range................... –65°C to 150°C PIN CONFIGURATION REFA ROFSA RFBA IOUT1A RVOSA RVOSB IOUT1B RFBB ROFSB REFB S1 WR REFA ROFSA RFBA IOUT1A RVOSA RVOSB IOUT1B RFBB ROFSB REFB S1 WR REFA ROFSA RFBA IOUT1A RVOSA RVOSB IOUT1B RFBB ROFSB REFB S1 WR 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 UPD READ D/S S0 IOUT2B GND NC NC NC NC D0 D1 RCOM RIN S2 IOUT2A GND D15 D14 D13 D12 D11 D10 D9 1 2 3 4 5 6 7 8 9 10 11 12 36 35 34 33 32 31 30 29 28 27 26 25 UPD READ D/S S0 IOUT2B GND NC NC D0 D1 D2 D3 49 13 14 15 16 17 18 19 20 21 22 23 24 D8 D7 VDD NC A1 A0 GND CLR MSPAN D6 D5 D4 LTC2753-16 UK PACKAGE 48-LEAD (7mm × 7mm) PLASTIC QFN 48 47 46 45 44 43 42 41 40 39 38 37 RCOM RIN S2 IOUT2A GND D11 D10 D9 D8 D7 D6 D5 1 2 3 4 5 6 7 8 9 10 11 12 36 35 34 33 32 31 30 29 28 27 26 25 UPD READ D/S S0 IOUT2B GND NC NC NC NC NC NC RCOM RIN S2 IOUT2A GND D13 D12 D11 D10 D9 D8 D7 1 2 3 4 5 6 7 8 9 10 11 12 48 47 46 45 44 43 42 41 40 39 38 37 49 49 13 14 15 16 17 18 19 20 21 22 23 24 D4 D3 VDD NC A1 A0 GND CLR MSPAN D2 D1 D0 13 14 15 16 17 18 19 20 21 22 23 24 D6 D5 VDD NC A1 A0 GND CLR MSPAN D4 D3 D2 LTC2753-14 UK PACKAGE 48-LEAD (7mm × 7mm) PLASTIC QFN LTC2753-12 UK PACKAGE 48-LEAD (7mm × 7mm) PLASTIC QFN TJMAX = 125°C, θJA = 29°C/W EXPOSED PAD (PIN 49) IS GND, MUST BE SOLDERED TO PCB TJMAX = 125°C, θJA = 29°C/W EXPOSED PAD (PIN 49) IS GND, MUST BE SOLDERED TO PCB TJMAX = 125°C, θJA = 29°C/W EXPOSED PAD (PIN 49) IS GND, MUST BE SOLDERED TO PCB ORDER INFORMATION LEAD FREE FINISH LTC2753CUK-12#PBF LTC2753IUK-12#PBF LTC2753CUK-14#PBF LTC2753IUK-14#PBF LTC2753BCUK-16#PBF LTC2753BIUK-16#PBF LTC2753ACUK-16#PBF LTC2753AIUK-16#PBF TAPE AND REEL LTC2753CUK-12#TRPBF LTC2753IUK-12#TRPBF LTC2753CUK-14#TRPBF LTC2753IUK-14#TRPBF LTC2753BCUK-16#TRPBF LTC2753BIUK-16#TRPBF LTC2753ACUK-16#TRPBF LTC2753AIUK-16#TRPBF PART MARKING* LTC2753UK-12 LTC2753UK-12 LTC2753UK-14 LTC2753UK-14 LTC2753UK-16 LTC2753UK-16 LTC2753UK-16 LTC2753UK-16 PACKAGE DESCRIPTION 48-Lead (7mm × 7mm) Plastic QFN 48-Lead (7mm × 7mm) Plastic QFN 48-Lead (7mm × 7mm) Plastic QFN 48-Lead (7mm × 7mm) Plastic QFN 48-Lead (7mm × 7mm) Plastic QFN 48-Lead (7mm × 7mm) Plastic QFN 48-Lead (7mm × 7mm) Plastic QFN 48-Lead (7mm × 7mm) Plastic QFN TEMPERATURE RANGE 0°C to 70°C –40°C to 85°C 0°C to 70°C –40°C to 85°C 0°C to 70°C –40°C to 85°C 0°C to 70°C –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/ 2753f 2 LTC2753 ELECTRICAL CHARACTERISTICS SYMBOL PARAMETER Static Performance Resolution Monotonicity DNL INL GE GETC BZE BZSTC PSR ILKG CIOUT1 Differential Nonlinearity Integral Nonlinearity Gain Error Gain Error Temperature Coefficient Bipolar Zero Error Bipolar Zero Temperature Coefficient Power Supply Rejection IOUT1 Leakage Current Output Capacitance VDD = 5V, ±10% VDD = 3V, ±10% TA = 25°C TMIN to TMAX Full-Scale Zero Scale ● ● ● ● ● ● VDD = 5V, VREF = 5V unless otherwise specified. The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. LTC2753-12 CONDITIONS MIN 12 12 ±1 ±1 ±0.5 ±0.6 ● LTC2753-14 MIN 14 14 ±1 ±1 ±1.5 ±0.6 ±1 ±0.6 ±0.5 ±3 ±5 TYP MAX LTC2753B-16 MIN 16 16 ±1 ±2 ±20 ±0.6 ±12 ±0.5 TYP MAX LTC2753A-16 MIN 16 16 ±0.2 ±0.4 ±4 ±0.6 ±2 ±0.5 ±8 ±1 ±1 ±14 TYP MAX UNITS Bits Bits LSB LSB LSB ppm/°C LSB ppm/°C LSB/V nA pF pF TYP MAX All Output Ranges ΔGain/ΔTemp All Bipolar Ranges ● ±2 ±0.2 ±0.5 ±0.025 ±0.06 ±0.05 ±2 ±5 ±0.05 75 45 ±0.1 ±0.25 ±2 ±5 ±0.05 75 45 ±0.4 ±1 ±2 ±5 ±0.03 ±0.2 ±0.1 ±0.5 ±0.05 75 45 ±2 ±5 ● 75 45 VDD = 5V, VREF = 5V unless otherwise specified. The ● denotes specifications that apply over the full operating temperature range, otherwise specifications are at TA = 25°C. SYMBOL Resistances (Note 3) R1, R2 RREF RFB ROFS RVOS Reference Inverting Resistors DAC Input Resistance Feedback Resistor Bipolar Offset Resistor Offset Adjust Resistor Output Settling Time Glitch Impulse Digital-to-Analog Glitch Impulse Multiplying Feedthrough Error THD Total Harmonic Distortion Output Noise Voltage Density 0V to 10V Range, 10V Step. To ±0.0015% FS (Note 5) (Note 6) (Note 7) 0V to 10V Range, VREF = ±10V, 10kHz Sine Wave (Note 8) Multiplying (Note 9) at IOUT1 (Note 3) (Note 3) (Note 4) ● ● ● ● ● PARAMETER CONDITIONS MIN 16 8 8 16 800 TYP 20 10 10 20 1000 2 1 1 0.5 –110 13 MAX UNITS kΩ kΩ kΩ kΩ kΩ μs nV•s nV•s mV dB ⎯ nV/√H⎯z Dynamic Performance 2753f 3 LTC2753 ELECTRICAL CHARACTERISTICS SYMBOL Power Supply VDD IDD Digital Inputs VIH VIL IIN CIN Digital Outputs VOH VOL IOH = 200μA IOL = 200μA ● ● VDD = 5V, VREF = 5V unless otherwise specified. The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. PARAMETER Supply Voltage Supply Current, VDD Digital Input High Voltage Digital Input Low Voltage Digital Input Current Digital Input Capacitance Digital Inputs = 0V or VDD 3.3V ≤ VDD ≤ 5.5V 2.7V ≤ VDD < 3.3V 4.5V < VDD ≤ 5.5V 2.7V ≤ VDD ≤ 4.5V VIN = GND to VDD VIN = 0V (Note 10) CONDITIONS ● ● MIN 2.7 TYP MAX 5.5 UNITS V μA V V 0.5 2.4 2 1 ● ● ● ● ● ● 0.8 0.6 ±1 6 VDD – 0.4 0.4 V V μA pF V V TIMING CHARACTERISTICS otherwise specifications are at TA = 25°C. SYMBOL PARAMETER VDD = 4.5V to 5.5V Write and Update Timing t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 t11 t12 t13 t14 t15 t26 t27 I/O Valid to WR Rising Edge Set-Up I/O Valid to WR Rising Edge Hold WR Pulse Width Low UPD Pulse Width High UPD Falling Edge to WR Falling Edge WR Rising Edge to UPD Rising Edge D/S Valid to WR Falling Edge Set-Up Time WR Rising Edge to D/S Valid Hold Time A1-A0 Valid to WR Falling Edge Setup Time WR Rising Edge to A1-A0 Valid Hold Time A1-A0 Valid to UPD Rising Edge Setup Time UPD Falling Edge to A1-A0 Valid Hold Time WR Rising Edge to READ Rising Edge READ Falling Edge to WR Falling Edge READ Rising Edge to I/O Propagation Delay A1-A0 Valid to READ Rising Edge Setup Time READ Falling to A1-A0 Valid Hold Time The ● denotes specifications that apply over the full operating temperature range, CONDITIONS MIN TYP MAX UNITS ● ● ● ● 7 7 15 15 0 0 7 7 5 0 9 7 7 20 40 20 0 ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns No Data Shoot-Through (Note 10) ● ● ● ● ● ● ● ● Readback Timing ● (Note 10) CL = 10pF (Note 10) ● ● ● ● 2753f 4 LTC2753 TIMING CHARACTERISTICS otherwise specifications are at TA = 25°C. PARAMETER UPD Valid to I/O Propagation Delay D/S Valid to READ Rising Edge READ Rising Edge to UPD Rising Edge UPD Falling Edge to READ Falling Edge READ Falling Edge to UPD Rising Edge I/O Bus Hi-Z to READ Rising Edge READ Falling Edge to I/O Bus Active CLR Pulse Width Low SYMBOL t17 t18 t19 t20 t22 t23 t24 CLR Timing t25 ● The ● denotes specifications that apply over the full operating temperature range, CONDITIONS CL = 10pF (Note 10) No Update No Update (Note 10) (Note 10) (Note 10) ● ● ● ● ● ● ● MIN 7 0 0 7 0 20 15 TYP MAX 26 UNITS ns ns ns ns ns ns ns ns VDD = 2.7V to 3.3V Write and Update Timing t1 t2 t3 t4 t5 t6 t7 t8 t9 t10 t11 t12 t13 t14 t15 t26 t27 t17 t18 t19 t20 I/O Valid to WR Rising Edge Set-Up I/O Valid to WR Rising Edge Hold WR Pulse Width Low UPD Pulse Width High UPD Falling Edge to WR Falling Edge WR Rising Edge to UPD Rising Edge D/S Valid to WR Falling Edge Set-Up Time WR Rising Edge to D/S Valid Hold Time A1-A0 Valid to WR Falling Edge Setup Time WR Rising Edge to A1-A0 Valid Hold Time A1-A0 Valid to UPD Rising Edge Setup Time UPD Falling Edge to A1-A0 Valid Hold Time WR Rising Edge to Read Rising Edge Read Falling Edge to WR Falling Edge Read Rising Edge to I/O Propagation Delay A1-A0 Valid to READ Rising Edge Setup Time READ Falling to A1-A0 Valid Hold Time UPD Valid to I/O Propagation Delay D/S Valid to Read Rising Edge Read Rising Edge to UPD Rising Edge UPD Falling Edge to Read Falling Edge (Note 10) CL = 10pF (Note 10) No Update No Update (Note 10) CL = 10pF No Data Shoot-Through (Note 10) ● ● ● ● ● ● ● ● ● ● ● ● 15 15 30 30 0 0 7 7 7 0 15 15 10 35 53 35 0 43 12 0 0 ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns ns Readback Timing ● ● ● ● ● ● ● ● ● 2753f 5 LTC2753 TIMING CHARACTERISTICS otherwise specifications are at TA = 25°C. PARAMETER READ Falling Edge to UPD Rising Edge I/O Bus Hi-Z to Read Rising Edge Read Falling Edge to I/O Bus Active CLR Pulse Width Low SYMBOL t22 t23 t24 CLR Timing t25 ● The ● denotes specifications that apply over the full operating temperature range, CONDITIONS (Note 10) (Note 10) (Note 10) ● ● ● MIN 10 0 35 20 TYP MAX UNITS ns ns ns ns VDD = 2.7V to 3.3V Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: Continuous operation above the specified maximum operating junction temperature may impair device reliability. Note 3: Because of the proprietary SoftSpan switching architecture, the measured resistance looking into each of the specified pins is constant for all output ranges if the IOUT1X and IOUT2X pins are held at ground. Note 4: R1 is measured from RIN to RCOM ; R2 is measured from REFA to RCOM . Note 5: Using LT1469 with CFEEDBACK = 15pF A ±0.0015% settling time . of 1.7μs can be achieved by optimizing the time constant on an individual basis. See Application Note 74, Component and Measurement Advances Ensure 16-Bit DAC Settling Time. Note 6: Measured at the major carry transition, 0V to 5V range. Output amplifier: LT1469; CFB = 27pF . Note 7. Full-scale transition; REF = 0V. Note 8. REF = 6VRMS at 1kHz. 0V to 5V range. DAC code = FS. Output amplifier = LT1469. ⎯ Note 9. Calculation from Vn = √4⎯k⎯T⎯R⎯B, where k = 1.38E-23 J/°K (Boltzmann constant), R = resistance (Ω), T = temperature (°K), and B = bandwidth (Hz). Note 10. Guaranteed by design. Not production tested. 2753f 6 LTC2753 TYPICAL PERFORMANCE CHARACTERISTICS LTC2753-16 Integral Nonlinearity (INL) 1.0 VDD = 5V 0.8 VREF = 5V ±10V RANGE 0.6 0.4 DNL (LSB) INL (LSB) 0.2 0.0 –0.2 –0.4 –0.6 –0.8 –1.0 0 16384 32768 CODE 49152 65535 2753 G01 TA = 25°C, unless otherwise noted. Differential Nonlinearity (DNL) VDD = 5V 0.8 VREF = 5V ±10V RANGE 0.6 0.4 INL (LSB) 0.2 0.0 –0.2 –0.4 –0.6 –0.8 –1.0 0 16384 32768 CODE 49152 65535 2753 G02 INL vs Temperature 1.0 VDD = 5V 0.8 VREF = 5V ±10V RANGE 0.6 +INL 1.0 0.4 0.2 0.0 –0.2 –0.4 –0.6 –0.8 –1.0 –40 –20 –INL 20 40 0 60 TEMPERATURE (°C) 80 2753 G04 DNL vs Temperature VDD = 5V 0.8 VREF = 5V ±10V RANGE 0.6 0.4 DNL (LSB) BZE (LSB) 0.2 0.0 –0.2 –0.4 –0.6 –0.8 –1.0 –40 –20 20 40 0 60 TEMPERATURE (°C) 80 2753 G05 Bipolar Zero vs Temperature 8 VDD = 5V 6 VREF = 5V ±10V RANGE 4 16 Gain Error vs Temperature VDD = 5V 12 VREF = 5V ±10V RANGE 8 1.0 +DNL –DNL GE (LSB) 2 0 2 4 6 8 –40 –20 0.5ppm/°C (TYP) 4 0 –4 –8 –12 0.6ppm/°C (TYP) 20 40 0 60 TEMPERATURE (°C) 80 2753 G06 –16 –40 –20 20 40 0 60 TEMPERATURE (°C) 80 2753 G07 INL vs VREF 1.0 VDD = 5V 0.8 ±5V RANGE 0.6 0.4 INL (LSB) INL (LSB) 0.2 0.0 –0.2 –0.4 –0.6 –0.8 –1.0 –10 –8 –6 4 202 VREF (V) 4 6 8 10 –INL +INL +INL 1.0 DNL vs VREF VDD = 5V 0.8 ±5V RANGE 0.6 0.4 0.2 0.0 –0.2 –0.4 –0.6 –0.8 –1.0 –10 –8 –6 4 202 VREF (V) 4 6 8 10 +DNL –DNL +DNL –DNL –INL 2753 G08 2751 G09 2753f 7 LTC2753 TYPICAL PERFORMANCE CHARACTERISTICS LTC2753-16 INL vs VDD 1.0 0.8 0.6 0.4 INL (LSB) 0.2 0.0 –0.2 –0.4 –0.6 –0.8 –1.0 2.5 3 3.5 4 VDD (V) 2751 G09b TA = 25°C, unless otherwise noted. Multiplying Frequency Response vs Digital Code 0 ALL BITS ON D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Settling 0V to 10V UPD 5V/DIV +INL GATED SETTLING WAVEFORM 250μV/DIV 2753 G10 –20 ATTENUATION (dB) –40 –60 –80 –INL 4.5 5 5.5 500ns/DIV USING LT1469 AMP CFEEDBACK = 12pF 0V TO 10V STEP –100 UNIPOLAR 5V OUTPUT RANGE LT1469 OUTPUT AMPLIFIER CFEEDBACK = 15pF –120 100 ALL BITS OFF 1k 10k 100k FREQUENCY (Hz) 1M 10M 2753 G10a LTC2753-14 Integral Nonlinearity (INL) VDD = 5V 0.8 VREF = 5V ±10V RANGE 0.6 0.4 DNL (LSB) INL (LSB) 0.2 0.0 –0.2 –0.4 –0.6 –0.8 –1.0 0 4096 8192 CODE 12288 16383 2753 G11 Differential Nonlinearity (DNL) VDD = 5V 0.8 VREF = 5V ±10V RANGE 0.6 0.4 0.2 0.0 –0.2 –0.4 –0.6 –0.8 –1.0 0 4096 8192 CODE 12288 16383 2753 G12 1.0 1.0 LTC2753-12 Integral Nonlinearity (INL) VDD = 5V 0.8 VREF = 5V ±10V RANGE 0.6 0.4 DNL (LSB) 0 1024 2048 CODE 4095 2753 G13 Differential Nonlinearity (DNL) 1.0 VDD = 5V 0.8 VREF = 5V ±10V RANGE 0.6 0.4 0.2 0.0 –0.2 –0.4 –0.6 –0.8 1.0 INL (LSB) 0.2 0.0 –0.2 –0.4 –0.6 –0.8 –1.0 3072 –1.0 0 1024 2048 CODE 3072 4095 2753 G14 2753f 8 LTC2753 TYPICAL PERFORMANCE CHARACTERISTICS LTC2753-12, LTC2753-14, LTC2753-16 Midscale Glitch 20 TA = 25°C, unless otherwise noted. Supply Current vs Logic Input Voltage 1nV•S (TYP) SUPPLY CURRENT (mA) UPD 5V/DIV 15 VDD = 5V 10 VOUT 2mV/DIV 5 VDD = 3V 0 0 1 2 3 4 DIGITAL INPUT VOLTAGE (V) 2753 G16 500ns/DIV USING AN LT1469 VDD = 5V CFEEDBACK = 27pF VREF = 5V 0V TO 5V RANGE 2753 G15 5 Logic Threshold vs Supply Voltage 2 1.75 1.5 1.25 FALLING 1 0.75 0.5 RISING SUPPLY CURRENT (mA) LOGIC THRESHOLD (V) 10 Supply Current vs Update Frequency 1 0.1 0.01 VDD = 5V 0.001 VDD = 3V 2.5 3 3.5 4 VDD (V) 4.5 5 5.5 2753 G17 0.0001 10 100 10k 100k 1k UPDATE FREQUENCY (Hz) 1M 2753 G18 2753f 9 LTC2753 PIN FUNCTIONS RCOM (Pin 1): Center Tap Point for the Reference Inverting Resistors. The 20k reference inverting resistors R1 and R2 are connected internally from RIN to RCOM and from RCOM to REFA, respectively (see Block Diagram). For normal operation tie RCOM to the negative input of the external reference inverting amplifier (see Typical Applications). RIN (Pin 2): Input Resistor R1 of the Reference Inverting Resistors. The 20k resistor R1 is connected internally from RIN to RCOM. For normal operation tie RIN to the external reference voltage VREF. Typically 5V; accepts up to ±15V. S2 (Pin 3): Span I/O Bit 2. Pins S0, S1 and S2 are used to program and to read back the output ranges of the DACs. IOUT2A (Pin 4): DAC A Current Output Complement. Tie IOUT2A to ground. GND (Pin 5): Shield Ground, provides necessary shielding for IOUT2A. Tie to ground. D3-D11 (Pins 6-14): LTC2753-12 Only. DAC Input/Output Data Bits. These I/O pins set and read back the DAC code. D11 is the MSB. D5-D13 (Pins 6-14): LTC2753-14 Only. DAC Input/Output Data Bits. These I/O pins set and read back the DAC code. D13 is the MSB. D7-D15 (Pins 6-14): LTC2753-16 Only. DAC Input/Output Data Bits. These I/O pins set and read back the DAC code. D15 is the MSB. VDD (Pin 15): Positive Supply Input 2.7V ≤ VDD ≤ 5.5V. Requires a 0.1μF bypass capacitor to GND. NC (Pin 16): No Internal Connection. A1 (Pin 17): DAC Address Bit 1. See Table 3. A0 (Pin 18): DAC Address Bit 0. See Table 3. GND (Pin 19): Ground. Tie to ground. CLR (Pin 20): Asynchronous Clear. When CLR is taken to a logic low, the data registers are reset to the zero-volt code for the present output range (VOUT = 0V). MSPAN (Pin 21): Manual Span Control Pin. MSPAN is used to configure the LTC2753 for operation in a single, fixed output range. When configured for single-span operation, the output range is set via hardware pin strapping. The input and DAC registers of the span I/O port are transparent and do not respond to write or update commands. To configure the part for single-span use, tie MSPAN directly to VDD . If MSPAN is instead connected to GND (SoftSpan configuration), the output ranges are set and verified by using write, update and read operations. See Manual Span Configuration in the Operation section. MSPAN must be connected either directly to GND (SoftSpan configuration) or VDD (single-span configuration). D0-D2 (Pins 22-24): LTC2753-12 Only. DAC Input/Output Data Bits. These I/O pins set and read back the DAC code. D0 is the LSB. D0-D4 (Pins 22-26): LTC2753-14 Only. DAC Input/Output Data Bits. These I/O pins set and read back the DAC code. D0 is the LSB. D0-D6 (Pins 22-28): LTC2753-16 Only. DAC Input/Output Data Bits. These I/O pins set and read back the DAC code. D0 is the LSB. NC (Pins 25-30): LTC2753-12 Only. No Internal Connection. NC (Pins 27-30): LTC2753-14 Only. No Internal Connection. NC (Pins 29, 30): LTC2753-16 Only. No Internal Connection. GND (Pin 31): Shield Ground, provides necessary shielding for IOUT2B. Tie to ground. IOUT2B (Pin 32): DAC B Current Output Complement. Tie IOUT2B to ground. S0 (Pin 33): Span I/O Bit 0. Pins S0, S1 and S2 are used to program and to read back the output range of the DACs. D/S (Pin 34): Data/Span Select. This pin is used to select the data I/O pins or the span I/O pins (D0 to D15 or S0 to S2, respectively), along with their respective dedicated registers, for write or read operations. Update operations ignore D/S, since all updates affect both data and span registers. For single-span operation, tie D/S to ground. READ (Pin 35): Read Pin. When READ is asserted high, the data I/O pins (D0-D15) or span I/O pins (S0-S2) 2753f 10 LTC2753 PIN FUNCTIONS output the contents of the selected register (see Table 1). For single-span operation, readback of the span I/O pins is disabled. UPD (Pin 36): Update and Buffer Select Pin. When READ is held low and UPD is asserted high, the contents of the addressed DAC’s input registers (both data and span) are copied into their respective DAC registers. The output of the DAC is updated, reflecting the new DAC register values. When READ is held high, the update function is disabled and the UPD pin functions as a buffer selector—logic low to select the input register, high to select the DAC register. See Readback in the Operation section. WR (Pin 37): Active Low Write Pin. A Write operation copies the data present on the data or span I/O pins (D0-D15 or S0-S2, respectively) into the associated input register. When READ is high, the Write function is disabled. S1 (Pin 38): Span I/O Bit 1. Pins S0, S1 and S2 are used to program and to read back the output ranges of the DACs. REFB (Pin 39): Reference Input for DAC B. The impedance looking into this pin is 10k to ground. For normal operation tie to the output of the reference inverting amplifier. Typically –5V; accepts up to ±15V. ROFSB (Pin 40): Bipolar Offset Network for DAC B. This pin provides the translation of the output voltage range for bipolar spans. Accepts up to ±15V; for normal operation tie to the positive reference voltage at RIN (Pin 2). The impedance looking into this pin is 20k to ground. RFBB (Pin 41): DAC B Feedback Resistor. For normal operation tie to the output of the I/V converter amplifier for DAC B (see Typical Applications). The DAC output current from IOUT1B flows through the feedback resistor to the RFBB pin. The impedance looking into this pin is 10k to ground. IOUT1B (Pin 42): DAC B Current Output. This pin is a virtual ground when the DAC is operating and should reside at 0V. For normal operation tie to the negative input of the I/V converter amplifier for DAC B (see Typical Applications). RVOSB (Pin 43): DAC B Offset Adjust. Nominal input range is ±5V. The impedance looking into this pin is 1M to ground. If not used, tie RVOSB to ground. RVOSA (Pin 44): DAC A Offset Adjust. Nominal input range is ±5V. The impedance looking into this pin is 1M to ground. If not used, tie RVOSA to ground. IOUT1A (Pin 45): DAC A Current Output. This pin is a virtual ground when the DAC is operating and should reside at 0V. For normal operation tie to the negative input of the I/V converter amplifier for DAC A (see Typical Applications). RFBA (Pin 46): DAC A Feedback Resistor. For normal operation tie to the output of the I/V converter amplifier for DAC A (see Typical Applications). The DAC output current from IOUT1A flows through the feedback resistor to the RFBA pin. The impedance looking into this pin is 10k to ground. ROFSA (Pin 47): Bipolar Offset Network for DAC A. This pin provides the translation of the output voltage range for bipolar spans. Accepts up to ±15V; for normal operation tie to the positive reference voltage at RIN (Pin 2). The impedance looking into this pin is 20k to ground. REFA (Pin 48): Reference Input for DAC A, and connection for internal reference inverting resistor R2. The 20k resistor R2 is connected internally from RCOM to REFA. For normal operation tie this pin to the output of the reference inverting amplifier (see Typical Applications). Typically –5V; accepts up to ±15V. The impedance looking into this pin is 10k to ground (RIN and RCOM floating). Exposed Pad (Pin 49): Ground. The Exposed Pad must be soldered to the PCB. 2753f 11 LTC2753 BLOCK DIAGRAM RIN 2 R1 DATA I /O 6-14, 22-28 16 I/O PORT DATA INPUT REGISTER 16 DATA DAC REGISTER RCOM 1 R2 16 DAC A 16-BIT WITH SPAN SELECT REFA ROFSA RFBA 48 47 46 45 IOUT1A SPAN I /O 3, 38, 33 3 I/O PORT SPAN INPUT REGISTER 3 SPAN DAC REGISTER 3 4 44 IOUT2A RVOSA RVOSB IOUT1B DAC ADDRESS A1 A0 17 18 DATA INPUT REGISTER 16 DATA DAC REGISTER 16 DAC B 16-BIT WITH SPAN SELECT 43 42 32 SPAN INPUT REGISTER 3 SPAN DAC REGISTER 3 IOUT2B CONTROL LOGIC 35 37 36 34 D/S 20 CLR 21 MSPAN 39 40 41 2753 BD READ WR UPD REFB ROFSB RFBB 2753f 12 LTC2753 TIMING DIAGRAMS Write, Update and Clear Timing t3 t1 WR t2 DATA/SPAN I/O INPUT t5 UPD t7 D/S t9 ADDRESS A1 - A0 VALID VALID VALID t6 t4 t8 t10 t11 VALID t25 t12 CLR 2753 TD01 Readback Timing READ t13 t14 WR t23 DATA/SPAN I/O INPUT t15 DATA/SPAN I/O OUTPUT t26 ADDRESS A1-A0 t19 UPD t18 D/S VALID VALID t20 t22 VALID t17 VALID t27 t24 2753 TD02 2753f 13 LTC2753 OPERATION Output Ranges The LTC2753 is a dual current-output, parallel-input precision multiplying DAC with software-programmable output ranges. SoftSpan provides two unipolar output ranges (0V to 5V and 0V to 10V), and four bipolar ranges (±2.5V, ±5V, ±10V and –2.5V to 7.5V). These ranges are obtained when an external precision 5V reference is used. When a reference voltage of 2V is used, the SoftSpan ranges become: 0V to 2V, 0V to 4V, ±1V, ±2V, ±4V and –1V to 3V. The output ranges are linearly scaled for references other than 2V and 5V. Digital Section The LTC2753 has 4 internal registers for each DAC, a total of 8 registers (see Block Diagram). Each DAC channel has two sets of double-buffered registers—one set for the data, and one set for the span (output range) of the DAC. The double-buffered feature provides the capability to simultaneously update the span and code, which allows smooth voltage transitions when changing output ranges. It also permits the simultaneous updating of multiple DACs. Each set of double-buffered registers comprises an input register and a DAC register. The input registers are holding buffers—when data is loaded into an input register via a write operation, the DAC outputs are not affected. The contents of a DAC register, on the other hand, directly control the DAC output voltage or output range. The contents of the DAC registers are changed by copying the contents of an input register into its associated DAC register via an update operation. Write and Update Operations The data input register of the addressed DAC is loaded directly from a 16-bit microprocessor bus by holding the D/S pin low and pulsing the WR pin low (write operation). The DAC register is loaded by pulsing the UPD pin high (update operation), which copies the data held in the input register into the DAC register. Note that updates always include both data and span; but the DAC register values will not change unless the input register values have previously been changed via a write operation. Loading the span input register is accomplished similarly, holding the D/S pin high and bringing the WR pin low. The span and data register structures are the same except for the number of parallel bits—the span registers have 3 bits, while the data registers have 12, 14, or 16. To make both registers transparent for flowthrough mode, tie WR low and UPD high. However, this defeats the deglitcher operation and output glitch impulse may increase. The deglitcher is activated on the rising edge of the UPD pin. The interface also allows the use of the input and DAC registers in a master-slave, or edge-triggered, configuration. This mode of operation occurs when WR and UPD are tied together and driven by a single clock signal. The data bits are loaded into the input register on the falling edge of the clock and then loaded into the DAC register on the rising edge. It is possible to control both data and span on one 16-bit wide data bus by allowing span pins S2 to S0 to share bus lines with the data LSBs (D2 to D0). No write or read operation includes both span and data, so there cannot be a conflict. The asynchronous clear pin resets both DACs to 0V in any output range. CLR resets all data registers, while leaving the span registers undisturbed. VDD LTC2753-16 VDD DAC A MSPAN S2 S1 S0 D/S WR UPD READ A1 A0 2753 F01 DAC B 16 DATA I/O Figure 1. Using MSPAN to Configure the LTC2753 for Single-Span Operation (±10V Range). 2753f 14 LTC2753 OPERATION These devices also have a power-on reset that initializes both DACs to VOUT = 0V in any output range. The DACs power up in the 0V-5V range if the part is in SoftSpan configuration; for manual span (see Manual Span Configuration below), both DACs power up in the manually-chosen range at the appropriate code. Manual Span Configuration Multiple output ranges are not needed in some applications. To configure the LTC2753 for single-span operation, tie the MSPAN pin to VDD and the D/S pin to GND. The desired output range is then specified by the span I/O pins (S0, S1 and S2) as usual, but the pins are programmed by tying directly to GND or VDD (see Figure 1 and Table 2). In this configuration, both DAC channels will initialize to the chosen output range at power-up, with VOUT = 0V. When configured for manual span operation, span pin readback is disabled. Readback The contents of any one of the 8 interface registers can be read back from the I/O ports. The I/O pins are grouped into two ports: data and span. The data I/O port comprises pins D0-D11, D0-D13 or D0-D15 (LTC2753-12, LTC2753-14 or LTC2753-16, respectively). The span I/O port comprises pins S0, S1 and S2 for all parts. Each DAC channel has a set of data registers that are controlled and read back from the data I/O port; and a set of span registers that are controlled and read back from the span I/O port. The register structure is shown in the Block Diagram. A readback operation is initiated by asserting READ to logic high after selecting the desired DAC channel and I/O port. The I/O pins, which are high-impedance digital inputs when READ is low, selectively change to low-impedance logic outputs during readback. Select the DAC channel with address pins A1 and A0, and select the I/O port (data or span) to be read back with the D/S pin. The selected I/O port’s pins become logic outputs during readback, while the unselected I/O port’s pins remain high-impedance inputs. With the DAC channel and I/O port selected, assert READ high and select the desired input or DAC register using the UPD pin. Note that UPD is a two function pin—the update function is only available when READ is low. When READ is high, the update function is disabled and the UPD pin instead selects the input or DAC register for readback. Table 1 shows the readback functions for the LTC2753. Table 1. Write, Update and Read Functions READ D/S 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 WR UPD 0 0 1 1 0 0 1 1 X X X X 0 1 0 1 0 1 0 1 0 1 0 1 SPAN I/O Update DAC Register Write to Input Register Write/Update (Transparent) Update DAC register Read Input Register Read DAC Register DATA I/O Write to Input Register Write/Update (Transparent) Update DAC Register Update DAC Register Read Input Register Read DAC Register - X = Don’t Care The most common readback task is to check the contents of an input register after writing to it, before updating the new data to the DAC register. To do this, hold UPD low and assert READ high. The contents of the selected port’s input register are output to its I/O pins. To read back the contents of a DAC register, hold UPD low and assert READ high, then bring UPD high to select the DAC register. The contents of the selected DAC register are output by the selected port’s I/O pins. Note: if no update is desired after the readback operation, UPD must be returned low before bringing READ low; otherwise the UPD pin will revert to its primary function and update the DAC. 2753f 15 LTC2753 OPERATION System Offset Adjustment Many systems require compensation for overall system offset. The RVOSA and RVOSB offset adjustment pins are provided for this purpose. For noise immunity and ease of adjustment, the control voltage is attenuated to the DAC output: VOS = –0.01 • V(RVOSX) [0V to 5V, ±2.5V spans] VOS = –0.02 • V(RVOSX) [0V to 10V, ±5V, –2.5V to 7.5V spans] VOS = –0.04 • V(RVOSX) [±10V span] The nominal input range of this pin is ±5V; other reference voltages of up to 15V may be used if needed. The RVOSX pins have an input impedance of 1MΩ. To preserve the settling performance of the LTC2753, drive this pin with a Thevenin-equivalent impedance of 10k or less. Short any unused system offset adjustment pins to IOUT2. Table 2. Span Codes S2 0 0 0 0 1 1 S1 0 0 1 1 0 0 S0 0 1 0 1 0 1 SPAN Unipolar 0V to 5V Unipolar 0V to 10V Bipolar –5V to 5V Bipolar –10V to 10V Bipolar –2.5V to 2.5V Bipolar –2.5V to 7.5V Codes not shown are reserved and should not be used. Table 3. Address Codes DAC CHANNEL A B ALL* A1 0 0 1 A0 0 1 1 Codes not shown are reserved and should not be used. *If readback is taken using the All DACs address, the LTC2753 defaults to DAC A. 2753f 16 LTC2753 OPERATION—EXAMPLES 1. Load ±5V range with the output at 0V. Note that since span and code are updated together, the output, if started at 0V, will stay there. The 16-Bit DAC code is shown in hex for compactness. WR SPAN I/O INPUT DATA I/O INPUT 010 8000H UPD UPDATE (±5V RANGE, VOUT = 0V) D/S READ = LOW 2753 TD03 2. Load ±10V range with the output at 5V, changing to –5V. WR SPAN I/O INPUT DATA I/O INPUT 011 C000H 4000H UPD UPDATE (5V) UPDATE (–5V) D/S READ = LOW 2753 TD04 3. Write and update midscale code in 0V to 5V range (VOUT = 2.5V) using readback to check the contents of the input and DAC registers before updating. WR DATA I/O INPUT DATA I/O HI-Z OUTPUT 8000H HI-Z 8000H INPUT REGISTER 0000H DAC REGISTER UPD D/S UPDATE (2.5V) READ 2753 TD05 2753f 17 LTC2753 APPLICATIONS INFORMATION Op Amp Selection Because of the extremely high accuracy of the 16-bit LTC2753-16, careful thought should be given to op amp selection in order to achieve the exceptional performance of which the part is capable. Fortunately, the sensitivity of INL and DNL to op amp offset has been greatly reduced compared to previous generations of multiplying DACs. Tables 4 and 5 contain equations for evaluating the effects of op amp parameters on the LTC2753’s accuracy when Table 4. Variables for Each Output Range That Adjust the Equations in Table 5 OUTPUT RANGE 5V 10V ±5V ±10V ±2.5V –2.5V to 7.5V A1 1.1 2.2 2 4 1 1.9 A2 2 3 2 4 1 3 A3 1 0.5 1 0.83 1.4 0.7 1 1 1 0.5 A4 A5 1 1.5 1.5 2.5 1 1.5 programmed in a unipolar or bipolar output range. These are the changes the op amp can cause to the INL, DNL, unipolar offset, unipolar gain error, bipolar zero and bipolar gain error. Tables 4 and 5 can also be used to determine the effects of op amp parameters on the LTC2753-14 and the LTC2753-12. However, the results obtained from Tables 4 and 5 are in 16-bit LSBs. Divide these results by 4 (LTC2753-14) and 16 (LTC2753-12) to obtain the correct LSB sizing. Table 6 contains a partial list of LTC precision op amps recommended for use with the LTC2753. The easy-to-use design equations simplify the selection of op amps to meet the system’s specified error budget. Select the amplifier from Table 6 and insert the specified op amp parameters in Table 5. Add up all the errors for each category to determine the effect the op amp has on the accuracy of the part. Arithmetic summation gives an (unlikely) worst-case effect. A root-sum-square (RMS) summation produces a more realistic estimate. Table 5. Easy-to-Use Equations Determine Op Amp Effects on DAC Accuracy in All Output Ranges (Circuit of Page 1). Subscript 1 Refers to Output Amp, Subscript 2 Refers to Reference Inverting Amp. OP AMP VOS1 (mV) INL (LSB) DNL (LSB) UNIPOLAR OFFSET (LSB) BIPOLAR ZERO ERROR (LSB) 5V A3 • VOS1 • 19.8 • V REF 5V IB1 • 0.13 •  V REF 0 A4 • VOS2 • 13.1 • B2 5V 5V 5V VOS1 • 0.82 • V A3 • VOS1 • 13.2 • V VOS1 • 3.2 • V REF REF REF 5V 5V 5V IB1 (nA) IB1 • 0.0003 •  V IB1 • 0.00008 •  V IB1 • 0.13 •  V REF REF REF 16.5k 1.5k AVOL1 (V/V) A1 • A A2 • A VOL1 VOL1 VOS2 (mV) IB2 (mV) AVOL2 (V/V) 0 0 0 0 0 0 0 0 0 () () () () () () () () () () REF (V5V ) ) 5V A4 • (I • 0.13 •  ( V )) A4 • ( 66k ) A REF VOL2 ( UNIPOLAR GAIN BIPOLAR GAIN ERROR (LSB) ERROR (LSB) 5V 5V VOS1 • 13.2 • V VOS1 • 13.2 • V REF REF 5V 5V IB1 • 0.0018 • V IB1 • 0.0018 • V REF REF 131k 131k A5 • 0 A5 • AVOL1 AVOL1 5V 5V VOS2 • 26.2 • VOS2 • 26.2 • VREF VREF 5V 5V IB2 • 0.26 • IB2 • 0.26 • VREF VREF 131k 131k AVOL2 AVOL2 () () () () () () () () () () () () Table 6. Partial List of LTC Precision Amplifiers Recommended for Use with the LTC2753 with Relevant Specifications AMPLIFIER SPECIFICATIONS VOS μV 25 50 60 70 75 125 IB nA 2 0.35 0.25 20 10 10 A VOL V/mV 800 1000 1500 4000 5000 2000 VOLTAGE NOISE ⎯ nV/√H⎯z 10 14 14 2.7 5 5 CURRENT NOISE ⎯ pA/√H⎯z 0.12 0.008 0.008 0.3 0.6 0.6 SLEW RATE V/μs 0.25 0.2 0.16 4.5 22 22 GAIN BANDWIDTH PRODUCT MHz 0.8 0.7 0.75 12.5 90 90 tSETTLING with LTC2753 μs 120 120 115 19 2 2 POWER DISSIPATION mW 46 11 10.5/Op Amp 69/Op Amp 117 123/Op Amp 2753f AMPLIFIER LT1001 LT1097 LT1112 (Dual) LT1124 (Dual) LT1468 LT1469 (Dual) 18 LTC2753 APPLICATIONS INFORMATION Op amp offset will contribute mostly to output offset and gain error, and has minimal effect on INL and DNL. For example, for the LTC2753-16 with a 5V reference in 5V unipolar mode, a 250μV op amp offset will cause a 3.3LSB zero-scale error and a 3.3LSB gain error; but only 0.8LSB of INL degradation and 0.2LSB of DNL degradation. While not directly addressed by the simple equations in Tables 4 and 5, temperature effects can be handled just as easily for unipolar and bipolar applications. First, consult an op amp’s data sheet to find the worst-case VOS and IB over temperature. Then, plug these numbers in the VOS and IB equations from Table 5 and calculate the temperature-induced effects. For applications where fast settling time is important, Application Note 74, Component and Measurement Advances Ensure 16-Bit DAC Settling Time, offers a thorough discussion of 16-bit DAC settling time and op amp selection. Precision Voltage Reference Considerations Much in the same way selecting an operational amplifier for use with the LTC2753 is critical to the performance of the system, selecting a precision voltage reference also requires due diligence. The output voltage of the LTC2753 is directly affected by the voltage reference; thus, any voltage reference error will appear as a DAC output voltage error. There are three primary error sources to consider when selecting a precision voltage reference for 16-bit applications: output voltage initial tolerance, output voltage temperature coefficient and output voltage noise. Initial reference output voltage tolerance, if uncorrected, generates a full-scale error term. Choosing a reference with low output voltage initial tolerance, like the LT1236 (±0.05%), minimizes the gain error caused by the reference; however, a calibration sequence that corrects for system zero- and full-scale error is always recommended. A reference’s output voltage temperature coefficient affects not only the full-scale error, but can also affect the circuit’s apparent INL and DNL performance. If a reference is chosen with a loose output voltage temperature coefficient, then the DAC output voltage along its transfer characteristic will be very dependent on ambient conditions. Minimizing the error due to reference temperature coefficient can be achieved by choosing a precision reference with a low output voltage temperature coefficient and/or tightly controlling the ambient temperature of the circuit to minimize temperature gradients. As precision DAC applications move to 16-bit and higher performance, reference output voltage noise may contribute a dominant share of the system’s noise floor. This in turn can degrade system dynamic range and signal-tonoise ratio. Care should be exercised in selecting a voltage reference with as low an output noise voltage as practical for the system resolution desired. Precision voltage references, like the LT1236, produce low output noise in the 0.1Hz to 10Hz region, well below the 16-bit LSB level in 5V or 10V full-scale systems. However, as the circuit bandwidths increase, filtering the output of the reference may be required to minimize output noise. Table 7. Partial List of LTC Precision References Recommended for Use with the LTC2753 with Relevant Specifications REFERENCE LT1019A-5, LT1019A-10 LT1236A-5, LT1236A-10 LT1460A-5, LT1460A-10 LT1790A-2.5 INITIAL TOLERANCE ±0.05% ±0.05% ±0.075% ±0.05% TEMPERATURE DRIFT 5ppm/°C 5ppm/°C 10ppm/°C 10ppm/°C 0.1Hz to 10Hz NOISE 12μVP-P 3μVP-P 20μVP-P 12μVP-P 2753f 19 LTC2753 APPLICATIONS INFORMATION Grounding As with any high resolution converter, clean grounding is important. A low impedance analog ground plane and star grounding techniques should be used. IOUT2 must be tied to the star ground with as low a resistance as possible. When it is not possible to locate star ground close to IOUT2, a low resistance trace should be used to route this pin to star ground. This minimizes the voltage drop from this pin to ground caused by the code dependent current flowing to ground. When the resistance of this circuit board trace becomes greater than 1Ω, a force/sense amplifier configuration should be used to drive this pin (see Figure 2). This preserves the excellent accuracy (1LSB INL and DNL) of the LTC2753-16. 2753f 20 LTC2753 APPLICATIONS INFORMATION ALTERNATE AMPLIFIER FOR OPTIMUM SETTLING TIME PERFORMANCE IOUT2 4,32 200Ω 200Ω 1000pF 3 IOUT2 1 ZETEX* BAT54S 2 3 6 2 2 2 3 *SCHOTTKY BARRIER DIODE VREF 5V ROFSA 47 RIN 2 3 45 IOUT1A 2 RCOM 1 DAC A 4 IOUT2A 150pF REFA 48 44 RVOSA 3 LTC2753-16 46 RFBA 15pF 1/2 LT1469 2753 F02 Figure 2. Optional Circuits for Driving IOUT2 from GND with a Force/Sense Amplifier. + – 1 + ZETEX BAT54S + – + 1 LT1468 LT1001 3 – 2 6 – 1/2 LT1469 1 VOUTA 2753f 21 LTC2753 TYPICAL APPLICATIONS Dual 16-Bit VOUT DAC with Software-Selectable Ranges VREF 5V ROFSA 47 RIN 2 3 R1 2 150pF C1* RCOM 1 R2 REFA 48 REFB 39 44 RVOSA 43 RVOSB DAC A 4 IOUT2A 3 LTC2753-16 46 RFBA C2 45 IOUT1A 15pF 1/2 LT1469 DAC B 42 IOUT1B ROFSB 40 DATA I/O D15 - D0 SPAN I/O S2 - S0 16 3 I/O PORT I/O PORT C3 41 RFBB 15pF 6 WR UPD READ D/S CLR MSPAN A1, A0 37 36 35 34 20 21 17, 18 ADDRESS WR UPD READ D/S CLR *FOR MULTIPLYING APPLICATIONS C1 = 15pF 22 – + 32 IOUT2B 5 + – 1/2 LT1469 1 VOUTA 1/2 LT1469 7 VOUTB 2753 F03 1 – + 2 2753f LTC2753 PACKAGE DESCRIPTION UK Package 48-Lead Plastic QFN (7mm × 7mm) (Reference LTC DWG # 05-08-1704 Rev C) 0.70 ± 0.05 5.15 ± 0.05 5.50 REF 6.10 ± 0.05 7.50 ± 0.05 (4 SIDES) 5.15 ± 0.05 PACKAGE OUTLINE 0.25 ± 0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 7.00 ± 0.10 (4 SIDES) 0.75 ± 0.05 R = 0.115 TYP R = 0.10 TYP 47 48 0.40 ± 0.10 1 2 PIN 1 CHAMFER C = 0.35 PIN 1 TOP MARK (SEE NOTE 6) 5.15 ± 0.10 5.50 REF (4-SIDES) 5.15 ± 0.10 0.200 REF 0.00 – 0.05 NOTE: 1. DRAWING CONFORMS TO JEDEC PACKAGE OUTLINE MO-220 VARIATION (WKKD-2) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE, IF PRESENT 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE (UK48) QFN 0406 REV C 0.25 ± 0.05 0.50 BSC BOTTOM VIEW—EXPOSED PAD 2753f Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. 23 LTC2753 TYPICAL APPLICATION Offset and Gain Trim Circuits. Powering VDD from LT1027 Ensures Quiet Supply V+ 2 C20 10μF IN U3 OUT 6 LT1027 TRIM 5 GND 4 2 1 GAIN TRIM R2 10k C13 10μF 2 8 V+ 1 OFFSET TRIM A 2 R1 10k 1 OFFSET TRIM B 2 R3 10k 1 – + 3 3 C23 0.1μF C22 0.001μF 3 U2A LT®1469 4 V– 15 6 7 8 9 10 11 12 13 14 22 23 24 25 26 27 28 47 40 2 1 48 39 46 RFBA C1 30pF IOUT1A IOUT2A DATA I/O RVOSA 44 RVOSB IOUT2B 43 8 V+ 1 IOUT1B SPAN I/O 3 S2 38 S1 33 S0 D/S READ UPD 34 35 36 WR 37 WR CLR 20 CLR MSPAN GND GND GND GND 21 5 31 19 49 RFBB 41 D/S READ UPD RELATED PARTS PART NUMBER LT1027 LT1236A-5 LT1468 LT1469 LTC1588/LTC1589/ LTC1592 LTC1591/LTC1597 LTC1821 LTC2601/LTC2611/ LTC2621 LTC2606/LTC2616/ LTC2626 LTC2641/LTC2642 LTC2704 LTC2751 DESCRIPTION Precision Reference Precision Reference 16-Bit Accurate Op-Amp Dual 16-Bit Accurate Op-Amp Serial 12-/14-/16-Bit IOUT Single DAC Parallel 14-/16-Bit IOUT Single DAC Parallel 16-Bit VOUT Single DAC Serial 12-/14-/16-Bit VOUT Single DACs Serial 12-/14-/16-Bit VOUT Single DACs Serial 12-/14-/16-Bit Unbuffered VOUT Single DACs Serial 12-/14-/16-Bit VOUT Quad DACs Parallel 12-/14-/16-Bit IOUT SoftSpan Single DACs COMMENTS 1ppm/°C Maximum Drift 0.05% Maximum Tolerance, 1ppm 0.1Hz to 10Hz Noise 90MHz GBW, 22V/μs Slew Rate 90MHz GBW, 22V/μs Slew Rate Software-Selectable (SoftSpan) Ranges, ±1LSB INL, DNL, 16-Lead SSOP Package Integrated 4-Quadrant Resistors ±1LSB INL, DNL, 0V to 10V, 0V to –10V, ±10V Output Ranges Single DACs, SPI-Compatible, Single Supply, 0V to 5V Outputs in 3mm × 3mm DFN-10 Package Single DACs, I2C-Compatible, Single Supply, 0V to 5V Outputs in 3mm × 3mm DFN-10 Package ±2LSB INL, ±1LSB DNL, 1μs Settling, Tiny MSOP-10, 3mm × 3mm DFN-10 Packages Software-Selectable (SoftSpan) Ranges, Integrated Amplifiers, ±2LSB INL ±1LSB INL, DNL, Software-Selectable (SoftSpan) Ranges, 5mm × 7mm QFN-38 Package 2753f LT 1007 • PRINTED IN USA 24 Linear Technology Corporation (408) 432-1900 ● FAX: (408) 434-0507 ● 1630 McCarthy Blvd., Milpitas, CA 95035-7417 www.linear.com © LINEAR TECHNOLOGY CORPORATION 2007 – 42 2 + 32 3 + 4 5 – U4B LT1469 7 VOUTA U4A LT1469 4 V– VOUTB C2 30pF 2753 TA03 D15 VDD ROFSA ROFSB RIN RCOM REFA REFB D14 D13 D12 D11 D10 D9 D8 U1 D7 D6 LTC2753-16 D5 D4 D3 D2 D1 D0 45 6