LTC1662 Ultralow Power, Dual 10-Bit DAC in MSOP DESCRIPTIO U FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ The LTC®1662 is an ultralow power, fully buffered voltage output, dual 10-bit digital-to-analog converter (DAC). Each DAC channel draws just 1.7µA (typ) total supplyplus-reference operating current, yet is capable of supplying DC output currents in excess of 1mA and reliably driving capacitive loads of up to 1000pF. A programmable Sleep mode further reduces total operating current to 0.05µA. Ultralow Power: 1.5µA (Typ) ICC per DAC Plus 0.05µA Sleep Mode for Extended Battery Life Tiny: Two 10-Bit DACs in an 8-Lead MSOP— Half the Size of an SO-8 Wide 2.7V to 5.5V Supply Range Double Buffered for Simultaneous DAC Updates Rail-to-Rail Voltage Outputs Drive 1000pF Reference Range Includes Supply for Ratiometric 0V-to-VCC Output Reference Input Impedance Is Code-Independent (7.1MΩ Typ)—Eliminates External Buffers 3-Wire Serial Interface with Schmitt Trigger Inputs Differential Nonlinearity: ±0.75LSB Max Linear Technology’s proprietary, inherently monotonic architecture provides excellent linearity and an exceptionally small external form factor. The double-buffered input logic provides simultaneous update capability and can be used to write to the DACs without interrupting Sleep mode. With its tiny operating current and exceptionally small size, the LTC1662 is ideal for use in the most powerconstrained products. For most designs, there is no perceptible impact on the power budget; the LTC1662 draws many times less current than even a trimpot, while providing buffered, low impedance (0.5Ω typical, VCC = 5V) rail-to-rail outputs. U APPLICATIO S ■ ■ ■ ■ ■ Mobile Communications Portable Battery-Powered Instruments Remote or Inaccessible Adjustments Digitally Controlled Amplifiers and Attenuators Factory or Field Calibration The LTC1662 is pin and software compatible with the LTC1661 dual, 60µA 10-bit DAC. It is available in 8-pin MSOP and PDIP packages and is specified over the industrial temperature range. , LTC and LT are registered trademarks of Linear Technology Corporation. W BLOCK DIAGRA 5 10-BIT DAC A LATCH VOUT B 6 LATCH VCC 7 LATCH GND 8 LATCH VOUT A Total Supply-Plus-Reference Operating Current 5.0 10-BIT DAC B 4.5 5.5V 4.5V 4.0 CONTROL LOGIC ICC + IREF (µA) 3.5 ADDRESS DECODER 3.0 2.5 3.6V 2.0 VCC = 2.7V 1.5 1.0 SHIFT REGISTER 0.5 VREF = VCC CODE = 1023 0 –55 –35 –15 1 2 3 CS/LD SCK SDI 4 REF 5 25 45 65 85 105 125 TEMPERATURE (°C) 1662 G02 1662 BD 1 LTC1662 W W W AXI U U ABSOLUTE RATI GS (Note 1) VCC to GND .............................................. – 0.3V to 7.5V Logic Inputs to GND ................................ – 0.3V to 7.5V VOUT A, VOUT B, REF to GND ......... – 0.3V to (VCC + 0.3V) Maximum Junction Temperature ......................... 125°C Storage Temperature Range ................ – 65°C to 150°C Operating Temperature Range LTC1662C ............................................. 0°C to 70°C LTC1662I ........................................... – 40°C to 85°C Lead Temperature (Soldering, 10 sec)................ 300°C U W U PACKAGE/ORDER I FOR ATIO ORDER PART NUMBER TOP VIEW CS/LD SCK SDI REF 1 2 3 4 8 7 6 5 VOUT A GND VCC VOUT B LTC1662CMS8 LTC1662IMS8 MS8 PACKAGE 8-LEAD PLASTIC MSOP MS8 PART MARKING TJMAX = 125°C, θJA = 150°C/W LTKB LTKC ORDER PART NUMBER TOP VIEW CS/LD 1 8 VOUT A SCK 2 7 GND SDI 3 6 VCC REF 4 5 VOUT B LTC1662CN8 LTC1662IN8 N8 PACKAGE 8-LEAD PLASTIC DIP TJMAX = 125°C, θJA = 100°C/W Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range (TA = TMIN to TMAX), otherwise specifications are at TA = 25°C. VCC = 2.7V to 5.5V, VREF ≤ VCC, VOUT Unloaded unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Accuracy Resolution DNL ● 10 Bits Monotonicity (Note 2) ● 10 Bits Differential Nonlinearity (Note 2) ● ±0.12 ±0.75 LSB INL Integral Nonlinearity (Note 2) ● ±0.8 ±4 LSB VOS Offset Error VCC = 5V, VREF = 4.096V, Measured at Code 20 ● ±5 ±25 mV VOS TC VOS Temperature Coefficient GE Gain Error GE TC Gain Error Temperature Coefficient PSR Power Supply Rejection ±15 VCC = 5V, VREF = 4.096V ±1 ● VREF = 2.5V µV/°C ±8 LSB ±12 µV/°C 0.18 LSB/V Reference Input Input Voltage Range Input Resistance Input Capacitance 2 Active Mode Sleep Mode ● 0 ● 3.9 VCC V 7.1 2.5 MΩ GΩ 10 pF LTC1662 ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range (TA = TMIN to TMAX), otherwise specifications are at TA = 25°C. VCC = 2.7V to 5.5V, VREF ≤ VCC, VOUT Unloaded unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Power Supply VCC Positive Supply Voltage For Specified Performance ICC Supply Current VCC = 3V (Note 3) VCC = 5V (Note 3) VCC = 3V (Note 3) VCC = 5V (Note 3) ● 2.7 5.5 V 3.0 3.5 4.0 4.5 5.0 5.5 µA µA µA µA 0.05 0.10 0.18 µA µA ● ● Sleep Mode Operating Current Supply Plus Reference Current, VCC = VREF = 5V (Note 3) ● DC Performance Short-Circuit Current Low VOUT = 0V, VCC = VREF = 5V, Code = 1023 (Note 7) ● 5 12 70 mA Short-Circuit Current High VOUT = VCC = VREF = 5V, Code = 0 (Note 7) ● 3 10 80 mA AC Performance Voltage Output Slew Rate Rising (Notes 4, 5) Falling (Notes 4, 5) Voltage Output Settling Time Rising 0.1VFS to 0.9VFS ±0.5LSB (Notes 4, 5) Falling 0.9VFS to 0.1VFS ±0.5LSB (Notes 4, 5) 20 7 Capacitive Load Driving V/ms V/ms 0.40 0.75 ms ms 1000 pF Digital I/O VIH Digital Input High Voltage VCC = 2.7V to 5.5V VCC = 2.7V to 3.6V ● ● VIL Digital Input Low Voltage VCC = 4.5V to 5.5V VCC = 2.7V to 5.5V ● ● ILK Digital Input Leakage VIN = GND to VCC ● CIN Digital Input Capacitance WU TI I G CHARACTERISTICS 2.4 2.0 V V ±0.05 0.8 0.6 V V ±1.0 µA 1.5 pF The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. SYMBOL PARAMETER CONDITIONS MIN TYP 55 15 MAX UNITS VCC = 4.5V to 5.5V t1 SDI Setup Relative to SCK Positive Edge ● t2 t3 ns SDI Hold Relative to SCK Positive Edge ● 0 – 10 ns SCK High Time (Note 6) ● 30 14 ns t4 SCK Low Time (Note 6) ● 30 14 ns t5 CS/LD Pulse Width (Note 6) ● 100 27 ns t6 LSB SCK High to CS/LD High (Note 6) ● 30 2 ns t7 CS/LD Low to SCK High (Note 6) ● 20 – 21 ns t9 SCK Low to CS/LD Low (Note 6) ● 0 –5 ns t11 CS/LD High to SCK Positive Edge (Note 6) ● 20 0 SCK Frequency Square Wave (Note 6) ● Relative to SCK Positive Edge (Note 6) ● ns 16.7 MHz VCC = 2.7V to 5.5V t1 SDI Setup t2 SDI Hold Relative to SCK Positive Edge (Note 6) t3 SCK High Time (Note 6) t4 SCK Low Time (Note 6) 75 20 ns ● 0 – 10 ns ● 50 15 ns ● 50 15 ns 3 LTC1662 WU TI I G CHARACTERISTICS The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. SYMBOL PARAMETER CONDITIONS MIN TYP t5 CS/LD Pulse Width (Note 6) t6 LSB SCK High to CS/LD High (Note 6) t7 CS/LD Low to SCK High t9 SCK Low to CS/LD Low t11 ● 150 30 ns ● 50 3 ns (Note 6) ● 30 – 14 ns (Note 6) ● 0 –5 ns CS/LD High to SCK Positive Edge (Note 6) ● 30 0 SCK Frequency Square Wave (Note 6) ● Note 1: Absolute maximum ratings are those values beyond which the life of a device may be impaired. Note 2: Nonlinearity and monotonicity are defined and tested at VCC = 5V, VREF = 4.096V, from code 20 to code 1023. See Figure 2. Note 3: Digital inputs at 0V or VCC. MAX UNITS ns 10 MHz Note 4: Load is 10kΩ in parallel with 100pF. Note 5: VCC = VREF = 5V. DAC switched between 0.1VFS and 0.9VFS; i.e., codes k = 102 and k = 922. Note 6: Guaranteed by design, not subject to test. Note 7: One DAC output loaded. U W TYPICAL PERFOR A CE CHARACTERISTICS Total Supply-Plus-Reference Operating Current Supply Current vs Temperature 5.0 4.5 4.0 4.5V 4.5V 2.5 2.0 3.6V VCC = 2.7V 2.5 VCC = 2.7V 0.5 0.5 VREF = VCC CODE = 1023 0 –55 –35 –15 5 25 45 65 85 105 125 TEMPERATURE (°C) 1 5 25 45 65 85 105 125 TEMPERATURE (°C) 1662 G01 0.6 0.5 0.4 0.3 0.2 3 2 1 0 –1 –2 0.1 –3 0 –4 1.5 1 1.5 2 2.5 3 3.5 4 LOGIC INPUT VOLTAGE (V) 4.5 10k 100k 1M FREQUENCY (Hz) 5 1662 G04 10M 100M 0.75 0.60 DIFFERENTIAL NONLINEARITY (LSB) INTEGRAL NONLINEARITY (LSB) 0.7 0 1k Differential Nonlinearity (DNL) 4 VCC = 5V ALL DIGITAL INPUTS SHORTED TOGETHER 0.8 100 1662 G03 Integral Nonlinearity (INL) 1.0 ICC (mA) 10 1662 G02 Supply Current vs Logic Input Voltage 0.9 VCC = 3V 10 1.5 1.0 0 –55 –35 –15 3.6V 2.0 1.0 VCC = 5V 100 3.0 ICC (µA) ICC + IREF (µA) 3.5 3.0 1.5 CS/LD = LOGIC LOW CODE = 0 5.5V 4.0 5.5V 3.5 ICC (µA) 1000 5.0 VREF = VCC CODE = 1023 4.5 4 Supply Current vs Clock Frequency 0.40 0.20 0 –0.20 –0.40 –0.60 –0.75 0 256 512 CODE 768 1023 1662 G05 0 256 512 CODE 768 1023 1662 G06 LTC1662 U W TYPICAL PERFOR A CE CHARACTERISTICS Integral Nonlinearity (INL) vs Reference Voltage Differential Nonlinearity (DNL) vs Reference Voltage 4 Offset Voltage vs Temperature 0 0.75 VCC = 5.5V 3 VCC = 5V VREF = 4.096V VCC = 5.5V 0.50 –1 MAX POS INL 0 –1 MAX NEG INL 0.25 OFFSET ERROR (mV) 1 PEAK DNL (LSB) PEAK INL (LSB) 2 MAX POS DNL 0 MAX NEG DNL –0.25 –2 –3 –2 –4 –0.50 –3 –4 1 2 3 4 5 0 6 1 2 3 4 5 Load Regulation vs Output Current at 5V Gain Error vs Temperature 0 1.0 VREF = VCC = 5V VOUT = 2.5V CODE = 512 TA = 25°C 0.8 –1 0.6 –3 0.6 0.4 0.2 0 –0.2 SOURCE –0.8 105 –5 –4 –3 –2 –1 0 1 IOUT (mA) 2 3 4 –1 –0.8–0.6–0.4– 0.2 0 0.2 0.4 0.6 0.8 IOUT (mA) 5 Output Amplifier Current Sinking Capability (Midscale) 5.0 Max/Min Output Voltage vs Source/ Sink Output Current (VCC = 5V) 5.0 3.0 4.0 VCC = 5.5V VCC = 5V VCC = 4.5V 3.5 2.5 2.0 1.5 3.0 4.5 3.5 2.5 2.0 1.5 VCC = 3.6V VCC = 3V VCC = 2.7V 1.0 0.5 0.5 10µ 100µ 1m 10m OUTPUT SOURCE CURRENT (A) 100m 1662 G13 VREF = VCC TA = 25°C 2.5 2.0 1.0 CODE = 0 0.5 0 1µ 3.0 1.5 VCC = 3.6V VCC = 3V VCC = 2.7V 1.0 0 CODE = 1023 4.0 VCC = 5.5V VCC = 5V VCC = 4.5V VOUT (V) 3.5 5.0 VREF = VCC CODE = 512 TA = 25°C 4.5 VOUT (V) 4.0 1 1662 G12 1662 G11 Output Amplifier Current Sourcing Capability (Midscale) VREF = VCC CODE = 512 TA = 25°C SINK –1.0 1662 G10 4.5 SOURCE –0.8 SINK –1.0 85 0 –0.2 –0.6 –0.6 –5 –55 –35 –15 5 25 45 65 TEMPERATURE (°C) 0.2 –0.4 –0.4 –4 VREF = VCC = 3V VOUT = 1.5V CODE = 512 TA = 25°C 0.8 ∆VOUT (LSB) ∆VOUT (LSB) 0.4 –2 105 Load Regulation vs Output Current at 3V 1.0 VCC = 5V VREF = 4.096V 85 1662 G09 1662 G08 1662 G07 GAIN ERROR (mV) 6 VREF (V) VREF (V) VOUT (V) –5 –55 –35 –15 5 25 45 65 TEMPERATURE (°C) –0.75 0 0 1µ 10µ 100µ 1m 10m OUTPUT SINK CURRENT (A) 100m 1662 G14 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 OUTPUT SOURCE/SINK CURRENT (mA) 5 1662 G15 5 LTC1662 U W TYPICAL PERFOR A CE CHARACTERISTICS Max/Min Output Voltage vs Source/ Sink Output Current (VCC = 3V) Output Minimum Series Resistance vs Load Capacitance Large-Signal Step Response 3.0 180 MINIMUM SERIES RESISTANCE (Ω) 5 2.7 CODE = 1023 2.4 4 1.8 VOUT (V) VOUT (V) 2.1 VREF = VCC TA = 25°C 1.5 1.2 3 2 0.9 0.6 CODE = 0 1 VREF = VCC = 5V 10% TO 90% STEP 0.3 0 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 OUTPUT SOURCE/SINK CURRENT (mA) 2 140 120 100 80 60 40 20 0 100p 1000p 0.01µ 0.1µ 1µ CAPACITANCE (F) 0 0 TIME (0.5ms/DIV) 1662 G16 160 1662 G17 10µ 100µ 1662 G18 U U U PI FU CTIO S CS/LD (Pin 1): Serial Interface Chip Select/Load Input. When CS/LD is low, SCK is enabled for shifting data on SDI into the register. When CS/LD is pulled high, SCK is disabled and the operation(s) specified in the Control code, A3-A0, is (are) performed. CMOS and TTL compatible. SCK (Pin 2): Serial Interface Clock Input. CMOS and TTL compatible. SDI (Pin 3): Serial Interface Data Input. Input word data on the SDI pin is shifted into the 16-bit register on the rising edge of SCK. CMOS and TTL compatible. REF (Pin 4): Reference Voltage Input. 0V ≤ VREF ≤ VCC. VOUT A, VOUT B (Pins 8,5): DAC Analog Voltage Outputs. The output range is 1023 0 ≤ VOUTA , VOUTB ≤ VREF 1024 VCC (Pin 6): Supply Voltage Input. 2.7V ≤ VCC ≤ 5.5V. GND (Pin 7): System Ground. U U DEFI ITIO S Differential Nonlinearity (DNL): The difference between the measured change and the ideal 1LSB change for any two adjacent codes. The DNL error between any two codes is calculated as follows: DNL = (∆VOUT – LSB)/LSB where ∆VOUT is the measured voltage difference between two adjacent codes. Full-Scale Error (FSE): The deviation of the actual fullscale voltage from ideal. FSE includes the effects of offset and gain errors (see Figure 2). 6 Gain Error (GE): The deviation from the slope of the ideal DAC transfer function, expressed in LSBs at full scale. Integral Nonlinearity (INL): The deviation from a straight line passing through the endpoints of the DAC transfer curve (Endpoint INL). Because the output cannot go below zero, the linearity is measured between full scale and the lowest code which guarantees the output will be greater than zero. The INL error at a given input code is calculated as follows: INL = [VOUT – VOS – (VFS – VOS)(code/1023)]/LSB LTC1662 U U DEFI ITIO S where VOUT is the output voltage of the DAC measured at the given input code. Voltage Offset Error (VOS): Nominally, the voltage at the output when the DAC is loaded with all zeros. A single supply DAC can have a true negative offset, but the output cannot go below zero (see Figure 2). Least Significant Bit (LSB): The ideal voltage difference between two successive codes. For this reason, single supply DAC offset is measured at the lowest code that guarantees the output will be greater than zero. LSB = VREF/1024 Resolution (n): Defines the number of DAC output states (2n) that divide the full-scale range. Resolution does not imply linearity. WU W TI I G DIAGRA t1 t2 t3 t6 t4 SCK t9 t11 SDI A3 t5 A1 A2 X1 X0 t7 CS/LD 1662 TD U OPERATIO SCK SDI 1 A3 2 A2 3 A1 CONTROL CODE 4 A0 5 D9 6 D8 7 D7 8 D6 9 D5 10 D4 11 D3 INPUT CODE 12 D2 13 D1 14 D0 15 X1 16 X0 DON’T CARE INPUT WORD W0 CS/LD (INSTRUCTION EXECUTED) 1662 F01 (SCK ENABLED) Figure 1. Register Loading Sequence 7 LTC1662 U OPERATIO Table 1. DAC Control Functions CONTROL A3 A2 A1 A0 INPUT REGISTER STATUS DAC REGISTER STATUS POWER-DOWN STATUS (SLEEP/WAKE) COMMENTS 0 0 0 0 No Change No Update No Change No Operation. Power-Down Status Unchanged (Part Stays In Wake or Sleep Mode) 0 0 0 1 Load DAC A No Update No Change Load Input Register A with Data. DAC Outputs Unchanged. Power-Down Status Unchanged 0 0 1 0 Load DAC B No Update No Change Load Input Register B with Data. DAC Outputs Unchanged. Power-Down Status Unchanged 1 0 0 0 No Change Update Outputs Wake Load Both DAC Regs with Existing Contents of Input Regs. Outputs Update. Part Wakes Up 1 0 0 1 Load DAC A Update Outputs Wake Load Input Reg A. Load DAC Regs with New Contents of Input Reg A and Existing Contents of Reg B. Outputs Update. Part Wakes Up 1 0 1 0 Load DAC B Update Outputs Wake Load Input Reg B. Load DAC Regs with Existing Contents of Input Reg A and New Contents of Reg B. Outputs Update. Part Wakes Up 1 1 0 1 No Change No Update Wake Part Wakes Up. Input and DAC Regs Unchanged. DAC Outputs Reflect Existing Contents of DAC Regs 1 1 1 0 No Change No Update Sleep Part Goes to Sleep. Input and DAC Regs Unchanged. DAC Outputs Set to High Impedance State 1 1 1 1 Load DACs A, B with Same 10-Bit Code Update Outputs Wake Load Both Input Regs. Load Both DAC Regs with New Contents of Input Regs. Outputs Update. Part Wakes Up Note: All control codes other than those shown are undefined and not subject to test. Transfer Function The transfer function for the LTC1662 is: k VOUT(IDEAL) = VREF 1024 at VCC (Pin 6) is in transition. If it is not possible to sequence the supplies, clamp the voltage at REF by connecting a Schottky diode between Pin 4 (anode) and Pin 6 (cathode). Serial Interface where k is the decimal equivalent of the binary DAC input code D9-D0 and VREF is the voltage at REF (Pin 4). See Table 2. The 16-bit Input word consists of the 4-bit Control code, the 10-bit Input code and two don’t-care bits. Power-On Reset Table 2. LTC1662 Input Word The LTC1662 actively clears the outputs to zero scale when power is first applied, making system initialization consistent and repeatable. Input Word A3 A2 A1 A0 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 X1 X0 Control Code Power Supply Sequencing The voltage at REF (Pin 4) should be kept within the range –0.3V ≤ VREF ≤ VCC + 0.3V (see Absolute Maximum Ratings). Particular care should be taken during power supply turn-on and turn-off sequences, when the voltage 8 Input Code Don’t Care After the Input word is loaded into the register (see Figure␣ 1), it is internally converted from serial to parallel format. The parallel 10-bit-wide Input code data path is then buffered by two latch registers. LTC1662 U OPERATIO The first of these, the Input Register, is used for loading new input codes. The second buffer, the DAC Register, is used for updating the DAC outputs. Each DAC has its own 10-bit Input Register and 10-bit DAC Register. Alternatively, one DAC may be loaded with a new input code during Sleep; then with just one command, the other DAC is loaded, the part is awakened and both outputs are updated. By selecting the appropriate 4-bit Control code (see Table␣ 1) it is possible to perform single operations, such as loading one DAC or changing Power-Down status (Sleep/Wake). In addition, some Control codes perform two or more operations at the same time. For example, one such code loads DAC A, updates both outputs and Wakes the part up. The DACs can be loaded separately or together, but the outputs are always updated together. For example, control code 0001b is used to load DAC A during Sleep. Then Control code 0101b loads DAC B, wakes the part and simultaneously updates both DAC outputs. Register Loading Sequence See Figure 1. With CS/LD held low, data on the SDI input is shifted into the 16-bit Shift Register on the positive edge of SCK. The 4-bit Control code, A3-A0, is loaded first, then the 10-bit Input code, D9-D0, ordered MSB-to-LSB in each case. Two don’t-care bits, X1 and X0, are loaded last. When the full 16-bit Input word has been shifted in, CS/LD is pulled high, causing the system to respond according to Table␣ 1. The clock is disabled internally when CS/LD is high. Note: SCK must be low when CS/LD is pulled low. Sleep Mode DAC control code 1110b is reserved for the special Sleep instruction (see Table 1). In this mode, static power consumption is greatly reduced. The reference input and analog outputs are set in a high impedance state and all DAC settings are retained in memory so that when Sleep mode is exited, the outputs of DACs not updated by the Wake command are restored to their last active state. Sleep mode is initiated by performing a load sequence using control code 1110b (the DAC input code D9-D0 is ignored). To save instruction cycles, the DACs may be prepared with new input codes during Sleep (control codes 0001b and 0010b); then, a single command (1000b) can be used both to wake the part and to update the output values. Voltage Outputs Each of the rail-to-rail output amplifiers contained in the LTC1662 can typically source or sink at least 1mA (VCC␣ =␣ 5V). The outputs swing to within a few millivolts of either supply when unloaded and have an equivalent output resistance of 130Ω (typical) when driving a load to the rails. The output amplifiers are stable driving capacitive loads of up to 1000pF. A small resistor placed in series with the output can be used to achieve stability for any load capacitance. Please see the Output Minimum Resistance vs Load Capacitance curve in the Typical Performance Characteristics section. Rail-to-Rail Output Considerations In any rail-to-rail DAC, the output swing is limited to voltages within the supply range. If the DAC offset is negative, the output for the lowest codes limits at 0V as shown in Figure 2b. Similarly, limiting can occur near full scale when the REF pin is tied to VCC. If VREF = VCC and the DAC full-scale error (FSE = VOS + GE) is positive, the output for the highest codes limits at VCC as shown in Figure 2c. No full-scale limiting can occur if VREF is less than VCC – FSE. Offset and linearity are defined and tested over the region of the DAC transfer function where no output limiting can occur. 9 LTC1662 U OPERATIO VREF = VCC POSITIVE FSE OUTPUT VOLTAGE INPUT CODE (2c) VREF = VCC OUTPUT VOLTAGE 0 512 INPUT CODE 1023 (2a) OUTPUT VOLTAGE 0V NEGATIVE OFFSET INPUT CODE (2b) 1662 F02 Figure 2. Effects of Rail-to-Rail Operation On a DAC Transfer Curve. (a) Overall Transfer Function (b) Effect of Negative Offset for Codes Near Zero Scale (c) Effect of Positive Full-Scale Error for Input Codes Near Full Scale When VREF = VCC U TYPICAL APPLICATIO S Micropower Trim Circuit with Coarse/Fine Adjustment. Total Supply Current Is 9.5µA 3.3V 0.1µF R2 1.1M 0.1µF 3.3V 2 LTC1258-2.5 1 2.5V 4 SDI SCK 3.3V 0.1µF 4 REF 6 VCC DAC A CS/LD R1 11k 2 R1 COARSE 11k 8 VOUT A 8 – LT1495 3 0.1µF 1 VOUT + 4 1 3 LTC1662 U1 2 DAC B 5 R2 FINE 1.1M VOUT B ( ( VOUT = VREF CODE A + R1 • CODE B R2 1024 1024 = 2.5V CODE A + 1 • CODE B 100 1024 1024 7 GND 1662 F04 10 ) ) LTC1662 U TYPICAL APPLICATIO S Using the LTC1258 and the LTC1662 In a Portable Application Powered by a Single Li-Ion Battery. Total Supply Current Is 8.2µA Li-Ion BATTERY INPUT VIN ≥ 4.3V 0.1µF 0.1µF 6 2 LTC1258-4.1 4 1 4.096V 4 3 2 1 VCC VOUT A REF 8 0V TO 4.096V (4mV/BIT) 5 0V TO 4.096V (4mV/BIT) SDI LTC1662 SCK CS/LD VOUT B GND 7 1662 F03 U PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted. MS8 Package 8-Lead Plastic MSOP (LTC DWG # 05-08-1660) 0.040 ± 0.006 (1.02 ± 0.15) 0.007 (0.18) 0.034 ± 0.004 (0.86 ± 0.102) 0.118 ± 0.004* (3.00 ± 0.102) 8 7 6 5 0° – 6° TYP SEATING PLANE 0.012 (0.30) 0.0256 REF (0.65) BSC 0.021 ± 0.006 (0.53 ± 0.015) 0.006 ± 0.004 (0.15 ± 0.102) 0.118 ± 0.004** (3.00 ± 0.102) 0.193 ± 0.006 (4.90 ± 0.15) MSOP (MS8) 1098 1 * DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE 4 2 3 N8 Package 8-Lead PDIP (Narrow 0.300) (LTC DWG # 05-08-1510) 0.300 – 0.325 (7.620 – 8.255) 0.009 – 0.015 (0.229 – 0.381) ( +0.035 0.325 –0.015 +0.889 8.255 –0.381 ) 0.045 – 0.065 (1.143 – 1.651) 0.400* (10.160) MAX 0.130 ± 0.005 (3.302 ± 0.127) 0.065 (1.651) TYP 8 7 6 5 1 2 3 4 0.255 ± 0.015* (6.477 ± 0.381) 0.100 (2.54) BSC 0.125 (3.175) 0.020 MIN (0.508) MIN 0.018 ± 0.003 (0.457 ± 0.076) N8 1098 *THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm) 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. 11 LTC1662 U TYPICAL APPLICATIO Ultralow Power DAC Optimizes Mixer Performance 3.3V 0.1µF 0.1µF 3.3V 2 LTC1258-2.5 1 2.5V 4 I LO 4 REF 6 IP VCC 3.9k 0.1% DAC A CS/LD SDI SCK 8 3.9k 0.1% 560k VOUT A 1 3.9k, 0.1% 3.9k 0.1% I 3 LO LTC1662 IP I+Q MIXER Q 2 DAC B 5 RF QP 3.9k 0.1% 560k 3.9k, 0.1% VOUT B 3.9k 0.1% 3.9k 0.1% Q 7 GND Q QP 1662 TA01 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1661 Dual 10-Bit VOUT DAC in 8-Lead MSOP Package VCC = 2.7V to 5.5V, 60µA per DAC, Rail-to-Rail Output LTC1663 Single 10-Bit VOUT DAC with 2-Wire Interface in SOT-23 Package VCC = 2.7V to 5.5V, Internal Reference, 60µA LTC1664 Quad 10-Bit VOUT DAC in 16-Pin Narrow SSOP VCC = 2.7V to 5.5V, 60µA per DAC, Rail-to-Rail Output LTC1665/LTC1660 Octal 8/10-Bit VOUT DAC in 16-Pin Narrow SSOP VCC = 2.7V to 5.5V, 60µA per DAC, Rail-to-Rail Output LTC1446/LTC1446L Dual 12-Bit VOUT DACs in SO-8 Package with Internal Reference LTC1446: VCC = 4.5V to 5.5V, VOUT = 0V to 4.095V LTC1446L: VCC = 2.7V to 5.5V, VOUT = 0V to 2.5V LTC1448 Dual 12-Bit VOUT DAC in SO-8 Package VCC = 2.7V to 5.5V, External Reference Can Be Tied to VCC LTC1454/LTC1454L Dual 12-Bit VOUT DACs in SO-16 Package with Added Functionality LTC1454: VCC = 4.5V to 5.5V, VOUT = 0V to 4.095V LTC1454L: VCC = 2.7V to 5.5V, VOUT = 0V to 2.5V LTC1458/LTC1458L Quad 12-Bit Rail-to-Rail Output DACs with Added Functionality LTC1458: VCC = 4.5V to 5.5V, VOUT = 0V to 4.095V LTC1458L: VCC = 2.7V to 5.5V, VOUT = 0V to 2.5V LTC1659 Single Rail-to-Rail 12-Bit VOUT DAC in 8-Lead MSOP Package VCC: 2.7V to 5.5V Low Power Multiplying VOUT DAC. Output Swings from GND to REF. REF Input Can Be Tied to VCC 12 Linear Technology Corporation 1662f LT/LCG 1000 4K • PRINTED IN THE USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408)432-1900 ● FAX: (408) 434-0507 ● www.linear-tech.com LINEAR TECHNOLOGY CORPORATION 2000