LTC2636HMS-HMX10#TRPBF

LTC2636 Octal 12-/10-/8-Bit SPI VOUT DACs with10ppm/°C Reference DESCRIPTION FEATURES n n n n n n n n n n n Integrated Precision Reference 2.5V Full-Scale 10ppm/°C (LTC2636-L) 4.096V Full-Scale 10ppm/°C (LTC2636-H) Maximum INL Error: 2.5LSB (LTC2636-12) Low Noise: 0.75mVP-P 0.1Hz to 200KHz Guaranteed Monotonic Over –40°C to 125°C Temperature Range Selectable Internal or External Reference 2.7V to 5.5V Supply Range (LTC2636-L) Ultralow Crosstalk Between DACs ( 4V requires VCC slew rates to be no greater than 110mV/µs. Note 4: Linearity and monotonicity are defined from code kL to code 2N–1, where N is the resolution and kL is given by kL = 0.016•(2N/VFS), rounded to the nearest whole code. For VFS = 2.5V and N = 12, kL = 26 and linearity is defined from code 26 to code 4,095. For VFS = 4.096V and N = 12, kL = 16 and linearity is defined from code 16 to code 4,095. Note 5: Inferred from measurement at code 16 (LTC2636-12), code 4 (LTC2636-10) or code 1 (LTC2636-8), and at full-scale. ns 50 l 200 MHz ns Note 6: This IC includes current limiting that is intended to protect the device during momentary overload conditions. Junction temperature can exceed the rated maximum during current limiting. Continuous operation above the specified maximum operating junction temperature may impair device reliability. Note 7: Digital inputs at 0V or VCC. Note 8: Guaranteed by design and not production tested. Note 9: Internal Reference mode. DAC is stepped 1/4 scale to 3/4 scale and 3/4 scale to 1/4 scale. Load is 2kΩ in parallel with 100pF to GND. Note 10: Temperature coefficient is calculated by dividing the maximum change in output voltage by the specified temperature range. Note 11: Thermal resistance of MSOP package limits IOUT to –5mA ≤ IOUT ≤ 5mA for H-grade MSOP parts and VCC = 5V ±10%. Rev D For more information www.analog.com 9 LTC2636 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTC2636-L12 (Internal Reference, VFS = 2.5V) Integral Nonlinearity (INL) 1.0 Differential Nonlinearity (DNL) 1.0 VCC = 3V 0.5 DNL (LSB) INL (LSB) 0.5 0 –0.5 –1.0 VCC = 3V 0 –0.5 0 1024 3072 2048 CODE –1.0 4095 1024 0 2048 CODE 3072 2636 G01 INL vs Temperature INL (POS) 1.260 VCC = 3V 0.5 0 INL (NEG) –0.5 –1.0 –50 –25 Reference Output Voltage vs Temperature DNL (POS) 0 DNL (NEG) –0.5 0 25 50 75 100 125 150 TEMPERATURE (°C) VCC = 3V 1.255 VREF (V) INL (LSB) 1.0 VCC = 3V 0.5 2636 G02 DNL vs Temperature DNL (LSB) 1.0 4095 1.250 1.245 –1.0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 2636 G03 1.240 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 2636 G04 Settling to ±1LSB Rising 2636 G05 Settling to ±1LSB Falling CS/LD 5V/DIV 3/4 SCALE TO 1/4 SCALE STEP VCC = 3V, VFS = 2.5V RL = 2k, CL = 100pF AVERAGE OF 256 EVENTS VOUT 1LSB/DIV 3.6µs 4.4µs VOUT 1LSB/DIV 1/4 SCALE TO 3/4 SCALE STEP VCC = 3V, VFS = 2.5V RL = 2k, CL = 100pF AVERAGE OF 256 EVENTS CS/LD 5V/DIV 2µs/DIV 2µs/DIV 2636 G06 2636 G07 Rev D 10 For more information www.analog.com LTC2636 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTC2636-H12 (Internal Reference, VFS = 4.096V) Integral Nonlinearity (INL) 1.0 Differential Nonlinearity (DNL) 1.0 VCC = 5V 0.5 DNL (LSB) INL (LSB) 0.5 0 0 –0.5 –0.5 –1.0 VCC = 5V 0 1024 3072 2048 CODE –1.0 4095 1024 0 2048 CODE 3072 2636 G09 2636 G08 INL vs Temperature 1.0 VCC = 5V INL (POS) INL (NEG) –0.5 DNL (POS) 0 DNL (NEG) 25 50 75 100 125 150 TEMPERATURE (°C) –1.0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 2636 G10 2.028 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 2636 G12 2636 G11 Settling to ±1LSB Rising Settling to ±1LSB Falling CS/LD 5V/DIV 1/4 SCALE TO 3/4 SCALE STEP VCC = 5V, VFS = 4.095V RL = 2k, CL = 100pF AVERAGE OF 256 EVENTS VOUT 1LSB/DIV 4.0µs VOUT 1LSB/DIV 2.048 2.038 –0.5 0 VCC = 5V 2.058 0.5 0 –1.0 –50 –25 2.068 VCC = 5V VREF (V) INL (LSB) 0.5 Reference Output Voltage vs Temperature DNL vs Temperature DNL (LSB) 1.0 4095 4.8µs 1/4 SCALE TO 3/4 SCALE STEP VCC = 5V, VFS = 4.095V RL = 2k, CL = 100pF AVERAGE OF 256 EVENTS CS/LD 5V/DIV 2µs/DIV 2µs/DIV 2636 G13 2636 G14 Rev D For more information www.analog.com 11 LTC2636 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTC2636-10 Integral Nonlinearity (INL) 1.0 Differential Nonlinearity (DNL) 1.0 VCC = 3V VFS = 2.5V INTERNAL REF. 0.5 DNL (LSB) INL (LSB) 0.5 0 –0.5 –1.0 VCC = 3V VFS = 2.5V INTERNAL REF. 0 –0.5 256 0 768 512 CODE –1.0 1023 256 0 512 CODE 768 2636 G15 1023 2636 G16 LTC2636-8 Integral Nonlinearity (INL) 0.50 Differential Nonlinearity (DNL) 0.50 VCC = 3V VFS = 2.5V INTERNAL REF. 0.25 DNL (LSB) INL (LSB) 0.25 0 0 –0.25 –0.25 –0.50 VCC = 3V VFS = 2.5V INTERNAL REF. 64 0 192 128 CODE –0.50 255 64 0 128 CODE 192 255 2636 G18 2636 G17 LTC2636 8 6 Current Limiting 0.20 VCC = 5V (LTC2636-H) VCC = 5V (LTC2636-L) VCC = 3V (LTC2636-L) 0.15 0.10 2 ΔVOUT (V) ΔVOUT (mV) 4 0 –2 –4 VCC = 5V (LTC2636-H) VCC = 5V (LTC2636-L) VCC = 3V (LTC2636-L) 2 0.05 0 –0.05 –0.01 –6 INTERNAL REF. CODE = MIDSCALE –8 –10 –30 Offset Error vs Temperature 3 OFFSET ERROR (mV) Load Regulation 10 –20 –10 0 10 IOUT (mA) 20 30 2636 G19 –0.15 –0.20 –30 INTERNAL REF. CODE = MIDSCALE –20 –10 0 10 IOUT (mA) 20 30 2636 G20 1 0 –1 –2 –3 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 2636 G21 Rev D 12 For more information www.analog.com LTC2636 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTC2636 Large-Signal Response Mid-Scale Glitch Impulse Power-On Reset Glitch LTC2636-L CS/LD 5V/DIV VOUT 0.5V/DIV VCC 2V/DIV LTC2636-H12, VCC = 5V 3.0nV•s TYP VOUT 5mV/DIV LTC2636-L12, VCC = 3V 2.1nV•s TYP VFS = VCC = 5V 1/4 SCALE to 3/4 SCALE 2µs/DIV 2µs/DIV 200µs/DIV 2636 G22 2636 G23 Headroom at Rails vs Output Current LTC2636-H 5V SOURCING VCC = 5V INTERNAL REF. 4.0 VOUT (V) 3.5 Power-On Reset to Mid-Scale VCC 2V/DIV CS/LD 2V/DIV 3V (LTC2636-L) SOURCING 3.0 2636 G24 Exiting Power-Down to Mid-Scale 5.0 4.5 LTC2636-H 2.5 2.0 1.5 DACs A-G IN VOUT POWER-DOWN MODE 0.5V/DIV 5V SINKING VOUT 0.5V/DIV 1.0 0 LTC2636-L 3V (LTC2636-L) SINKING 0.5 0 1 2 3 4 5 6 IOUT (mA) 7 8 9 5µs/DIV 10 200µs/DIV 2636 G26 2636 G27 2636 G25 Supply Current vs Logic Voltage 1.5 Hardware CLR Hardware CLR to Mid-Scale VCC = 5V VREF = 4.096V CODE = FULL-SCALE SWEEP SCK, SDI, CS/LD BETWEEN 0V AND VCC 1.4 VOUT 1V/DIV ICC (mA) ZERO-SCALE VOUT 5mV/DIV VOUT 1V/DIV VCC = 5V VREF = 4.096V CODE = FULL-SCALE 1.2 VCC = 5V 1.0 VCC = 3V (LTC2636-L) 0.8 0.6 0 1 2 3 LOGIC VOLTAGE (V) CLR 5V/DIV CLR 5V/DIV 4 5 1µs/DIV 1µs/DIV 2636 G29 2636 G30 2636 G28 Rev D For more information www.analog.com 13 LTC2636 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. LTC2636 Multiplying Bandwidth Noise Voltage vs Frequency 2 500 0 NOISE VOLTAGE (nV/√Hz) –2 –4 dB –6 –8 –10 –12 VCC = 5V VREF(DC) = 2V VREF(AC) = 0.2VP-P CODE = FULL-SCALE –14 –16 –18 1k 10k 100k FREQUENCY (Hz) 400 VCC = 5V CODE = MID-SCALE INTERNAL REF. 300 LTC2636-H 200 LTC2636-L 100 0 100 1M 1k 10k 100k FREQUENCY (Hz) 2636 G31 2636 G32 Gain Error vs Reference Input 0.1Hz to 10Hz Voltage Noise 1.0 VCC = 5V, VFS = 2.5V CODE = MIDSCALE INTERNAL REF. VCC = 5.5V 0.8 GAIN ERROR OF 8 CHANNELS 0.6 GAIN ERROR (%FSR) 1M 0.4 0.2 10µV/DIV 0 –0.2 –0.4 –0.6 –0.8 –1.0 1 1.5 2 2.5 3 3.5 4 4.5 REFERENCE VOLTAGE (V) 5 1s/DIV 5.5 2636 G34 2636 G33 DAC to DAC Crosstalk (Dynamic) Gain Error vs Temperature 1.0 GAIN ERROR (%FSR) CS/LD 5V/DIV 1 DAC SWITCH 0-FS 2V/DIV VOUT 1mV/DIV LTC2636-H12, VCC = 5V 2.4nV•s TYP CREF = 0.1µF 2µs/DIV 2636 G35 0.5 0 –0.5 –1.0 –50 –25 0 25 50 75 100 125 150 TEMPERATURE (°C) 2636 G36 Rev D 14 For more information www.analog.com LTC2636 PIN FUNCTIONS (DFN/MSOP) VCC (Pin 1/1): Supply Voltage Input. 2.7V ≤ VCC ≤ 5.5V (LTC2636-L) or 4.5V ≤ VCC ≤ 5.5V (LTC2636-H). Bypass to GND with a 0.1μF capacitor. VOUT A to VOUT H (Pins 2-5, 10-13/2-5, 12-15): DAC Analog Voltage Outputs. CS/LD (Pin 6/7): 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 taken high, SCK is disabled and the specified command (see Table 1) is executed. SCK (Pin 7/8): Serial Interface Clock Input. CMOS and TTL compatible. SDI (Pin 8/9): Serial Interface Data Input. Data on SDI is clocked into the DAC on the rising edge of SCK. The LTC2636 accepts input word lengths of either 24 or 32 bits. REF (Pin 9/11): Reference Voltage Input or Output. When External Reference mode is selected, REF is an input (1V ≤ VREF ≤ VCC) where the voltage supplied sets the full-scale DAC output voltage. When Internal Reference is selected, the 10ppm/°C 1.25V (LTC2636-L) or 2.048V (LTC2636-H) internal reference (half full-scale) is available at REF. This output may be bypassed to GND with up to 10μF, and must be buffered when driving external DC load current. GND (Pin 14/16): Ground. LDAC (Pin 6, MSOP only): Asynchronous DAC Update Pin. If CS/LD is high, a falling edge on LDAC immediately updates the DAC registers with the contents of the input registers (similar to a software update). If CS/LD is low when LDAC goes low, the DAC registers are updated after CS/LD returns high. A low on the LDAC pin powers up the DACs. A software power down command is ignored if LDAC is low. If the LDAC functionality is not being used, the LDAC pin should be tied high. CLR (Pin 10, MSOP only): Asynchronous Clear Input. A logic low at this level-triggered input clears all registers and causes the DAC voltage output to reset to Zero (LTC2636-Z) or Mid-scale (LTC2636-MI/-MX). CMOS and TTL compatible. Exposed Pad (Pin 15, DFN Only): Ground. Must be soldered to PCB Ground. Rev D For more information www.analog.com 15 LTC2636 BLOCK DIAGRAM SWITCH INTERNAL REFERENCE REF VREF GND REGISTER REGISTER DAC A REGISTER VOUTA REGISTER VCC DAC H VREF REGISTER REGISTER DAC B REGISTER REGISTER VREF VOUTB DAC G REGISTER REGISTER REGISTER REGISTER DAC C DAC F VOUTF VREF REGISTER REGISTER DAC D REGISTER REGISTER VREF VOUTD VOUTG VREF VREF VOUTC VOUTH DAC E VOUTE CS/LD CONTROL LOGIC SDI DECODE SCK (LDAC) 32-BIT SHIFT REGISTER (CLR) POWER-ON RESET 2636 BD ( ) MSOP PACKAGE ONLY TIMING DIAGRAMS t1 t2 SCK t3 1 t6 t4 2 3 23 24 t10 SDI t5 t7 CS/LD t11 t9 LDAC 2636 F01a Figure 1a CS/LD t11 LDAC 2636 F01b Figure 1b Rev D 16 For more information www.analog.com LTC2636 OPERATION The LTC2636 is a family of octal voltage output DACs in 14-lead DFN and 16-lead MSOP packages. Each DAC can operate rail-to-rail using an external reference, or with its full-scale voltage set by an integrated reference. Eighteen combinations of accuracy (12-, 10-, and 8-bit), poweron reset value (zero-scale, mid-scale in internal reference mode, or mid-scale in external reference mode), and full-scale voltage (2.5V or 4.096V) are available. The LTC2636 is controlled using a 3-wire SPI/MICROWIRE compatible interface. Power-On Reset Transfer Function The digital-to-analog transfer function is: ⎛k ⎞ VOUT(IDEAL) = ⎜ n ⎟ VREF ⎝2 ⎠ where k is the decimal equivalent of the binary DAC input code, n is the resolution, and VREF is either 2.5V (LTC2636-LMI/-LMX/-LZ) or 4.096V (LTC2636-HMI/HMX/-HZ) when in Internal Reference mode, and the voltage at REF when in External Reference mode. Table 1. Command Codes The LTC2636-HZ/-LZ clear the output to zero-scale when power is first applied, making system initialization consistent and repeatable. For some applications, downstream circuits are active during DAC power-up, and may be sensitive to nonzero outputs from the DAC during this time. The LTC2636 contains circuitry to reduce the power-on glitch: the analog output typically rises less than 5mV above zeroscale during power on. In general, the glitch amplitude decreases as the power supply ramp time is increased. See “Power-On Reset Glitch” in the Typical Performance Characteristics section. The LTC2636-HMI/-HMX/-LMI/-LMX provide an alternative reset, setting the output to mid-scale when power is first applied. The LTC2636-LMI and LTC2636-HMI power up in internal reference mode, with the output set to a mid-scale voltage of 1.25V and 2.048V respectively. The LTC2636-LMX and LTC2636-HMX power-up in external reference mode, with the output set to mid-scale of the external reference. Default reference mode selection is described in the Reference Modes section. COMMAND* C3 C2 C1 C0 0 0 0 0 Write to Input Register n 0 0 0 1 Update (Power-Up) DAC Register n 0 0 1 0 Write to Input Register n, Update (Power-Up) All 0 0 1 1 Write to and Update (Power-Up) DAC Register n 0 1 0 0 Power-Down DAC n 0 1 0 1 Power-Down Chip (All DAC’s and Reference) 0 1 1 0 Select Internal Reference (Power-Up Reference) 0 1 1 1 Select External Reference (Power-Down Internal Reference) 1 1 1 1 No Operation *Command codes not shown are reserved and should not be used. Table 2. Address Codes ADDRESS (n)* A3 A2 A1 A0 0 0 0 0 DAC A 0 0 0 1 DAC B 0 0 1 0 DAC C 0 0 1 1 DAC D 0 1 0 0 DAC E Power Supply Sequencing 0 1 0 1 DAC F The voltage at REF (Pin 9-DFN, Pin 11-MSOP) must be kept within the range –0.3V ≤ VREF ≤ VCC + 0.3V (see Absolute Maximum Ratings). Particular care should be taken to observe these limits during power supply turnon and turn-off sequences, when the voltage at VCC is in transition. 0 1 1 0 DAC G 0 1 1 1 DAC H 1 1 1 1 ALL DACS *Address codes not shown are reserved and should not be used. Rev D For more information www.analog.com 17 LTC2636 OPERATION INPUT WORD (LTC2636-12) COMMAND C3 C2 C1 ADDRESS C0 A3 A2 A1 DATA (12 BITS + 4 DON'T-CARE BITS) A0 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 MSB D0 X X X X X X X X X X X X X X LSB INPUT WORD (LTC2636-10) COMMAND C3 C2 C1 ADDRESS C0 A3 A2 A1 DATA (10 BITS + 6 DON'T-CARE BITS) A0 D9 D8 D7 D6 D5 D4 D3 D2 D1 MSB D0 X LSB INPUT WORD (LTC2636-8) COMMAND C3 C2 C1 ADDRESS C0 A3 A2 A1 DATA (8 BITS + 8 DON'T-CARE BITS) A0 D7 D6 D5 D4 D3 D2 D1 MSB D0 X LSB X X 2636 F02 Figure 2. Command and Data Input Format Serial Interface The CS/LD input is level triggered. When this input is taken low, it acts as a chip-select signal, enabling the SDI and SCK buffers and the input shift register. Data (SDI input) is transferred into the LTC2636 on the next 24 rising SCK edges. The 4-bit command, C3-C0, is loaded first; then the 4-bit DAC address, A3-A0; and finally the 16-bit data word. The data word comprises the 12-, 10- or 8-bit input code, ordered MSB-to-LSB, followed by 4, 6 or 8 don’t-care bits (LTC2636-12, -10 and -8 respectively; see Figure 2). Data can only be transferred to the device when the CS/LD signal is low, beginning on the first rising edge of SCK. SCK may be high or low at the falling edge of CS/LD. The rising edge of CS/LD ends the data transfer and causes the device to execute the command specified in the 24-bit input sequence. The complete sequence is shown in Figure 3a. The command (C3-C0) and address (A3-A0) assignments are shown in Tables 1 and 2. The first four commands in Table 1 consist of write and update operations. A Write operation loads a 16-bit data word from the 24-bit shift register into the input register of the selected DAC, n. An Update operation copies the data word from the input register to the DAC register. Once copied into the DAC register, the data word becomes the active 12-, 10-, or 8-bit input code, and is converted to an analog voltage at the DAC output. Write to and Update combines the first 18 two commands. The Update operation also powers up the DAC if it had been in power-down mode. The data path and registers are shown in the Block Diagram. While the minimum input sequence is 24 bits, it may optionally be extended to 32 bits to accommodate microprocessors that have a minimum word width of 16 bits (2 bytes). To use the 32-bit width, 8 don’t-care bits must be transferred to the device first, followed by the 24-bit sequence described. Figure 3b shows the 32-bit sequence. The 16-bit data word is ignored for all commands that do not include a Write operation. Reference Modes For applications where an accurate external reference is either not available, or not desirable due to limited space, the LTC2636 has a user-selectable, integrated reference. The integrated reference voltage is internally amplified by 2x to provide the full-scale DAC output voltage range. The LTC2636-LMI/-LMX/-LZ provides a full-scale DAC output of 2.5V. The LTC2636-HMI/-HMX/-HZ provides a full-scale DAC output of 4.096V. The internal reference can be useful in applications where the supply voltage is poorly regulated. Internal Reference mode can be selected by using command 0110b, and is the power-on default for LTC2636-HZ/-LZ, as well as for LTC2636-HMI/-LMI. For more information www.analog.com Rev D SDI SCK CS/LD X 1 X 2 X For more information www.analog.com X 4 X 5 C2 X 8 DON’T-CARE BITS 3 C3 SDI 2 C1 3 6 X 7 4 8 C0 X COMMAND WORD 1 SCK CS/LD 7 A1 ADDRESS A2 6 A0 8 D11 9 D10 10 D9 D8 12 D7 13 D6 14 24-BIT INPUT WORD 11 D5 15 D3 17 DATA WORD D4 16 D2 18 D1 19 C3 C2 10 C1 11 C0 12 A1 15 ADDRESS A2 14 A0 16 32-BIT INPUT WORD A3 13 D11 17 D10 18 D9 19 D8 20 D7 21 D6 22 D5 23 D3 25 X 21 DATA WORD D4 24 D0 20 D2 26 X 22 D1 27 X 23 D0 28 X 24 X 29 30 X 2636 F03a X 31 X 32 2636 F03b OPERATION Figure 3b. LTC2636-12 32-Bit Load Sequence. LTC2636-10 SDI Data Word: 10-Bit Input Code + 6 Don’t-Care Bits; LTC2636-8 SDI Data Word: 8-Bit Input Code + 8 Don’t-Care Bits COMMAND WORD 9 Figure 3a. LTC2636-12 24-Bit Load Sequence (Minimum Input Word). LTC2636-10 SDI Data Word: 10-Bit Input Code + 6 Don’t-Care Bits; LTC2636-8 SDI Data Word: 8-Bit Input Code + 8 Don’t-Care Bits A3 5 LTC2636 Rev D 19 LTC2636 OPERATION The 10ppm/°C, 1.25V (LTC2636-LMI/-LMX/-LZ) or 2.048V (LTC2636-HMI/-HMX/-HZ) internal reference is available at the REF pin. Adding bypass capacitance to the REF pin will improve noise performance; and up to 10μF can be driven without oscillation. The REF output must be buffered when driving an external DC load current. Alternatively, the DAC can operate in External Reference mode using command 0111b. In this mode, an input voltage supplied externally to the REF pin provides the reference (1V ≤ VREF ≤ VCC) and the supply current is reduced. The external reference voltage supplied sets the full-scale DAC output voltage. External Reference mode is the power-on default for LTC2636-HMX/-LMX. The reference mode of LTC2636-HZ/-LZ/-HMI/-LMI (Internal Reference power-on default), can be changed by software command after power-up. The same is true for LTC2636HMX/-LMX (External Reference power-on default). Power-Down Mode For power-constrained applications, power-down mode can be used to reduce the supply current whenever less than eight DAC outputs are needed. When in powerdown, the buffer amplifiers, bias circuits, and integrated reference circuits are disabled, and draw essentially zero current. The DAC outputs are put into a high-impedance state, and the output pins are passively pulled to ground through individual 200k resistors. Input- and DAC-register contents are not disturbed during power-down. Any DAC channel or combination of channels can be put into power-down mode by using command 0100b in combination with the appropriate DAC address, (n). The supply current is reduced approximately 10% for each DAC powered down. The integrated reference is automatically powered down when external reference is selected using command 0111b. In addition, all the DAC channels and the integrated reference together can be put into powerdown mode using Power Down Chip command 0101b. When the integrated reference and all DAC channels are in power-down mode, the REF pin becomes high impedance (typically > 1GΩ). For all power-down commands the 16- bit data word is ignored. Normal operation resumes after executing any command that includes a DAC update, (as shown in Table 1) or using the asynchronous LDAC pin. The selected DAC is powered up as its voltage output is updated. When a DAC which is in a powered-down state is powered up and updated, normal settling is delayed. If less than eight DACs are in a powered-down state prior to the update command, the power-up delay time is 10μs. However, if all eight DACs and the integrated reference are powered down, then the main bias generation circuit block has been automatically shut down in addition to the DAC amplifiers and reference buffers. In this case, the power up delay time is 12μs. The power-up of the integrated reference depends on the command that powered it down. If the reference is powered down using the Select External Reference Command (0111b), then it can only be powered back up using Select Internal Reference Command (0110b). However, if the reference was powered down using Power Down Chip Command (0101b), then in addition to Select Internal Reference Command (0110b), any command (in software or using the LDAC pin) that powers up the DACs will also power up the integrated reference. Voltage Outputs The LTC2636’s integrated rail-to-rail amplifiers have guaranteed load regulation when sourcing or sinking up to 10mA at 5V, and 5mA at 3V. Load regulation is a measure of the amplifier’s ability to maintain the rated voltage accuracy over a wide range of load current. The measured change in output voltage per change in forced load current is expressed in LSB/mA. DC output impedance is equivalent to load regulation, and may be derived from it by simply calculating a change in units from LSB/mA to ohms. The amplifier’s DC output impedance is 0.1Ω when driving a load well away from the rails. When drawing a load current from either rail, the output voltage headroom with respect to that rail is limited by the 50Ω typical channel resistance of the output devices (e.g., when sinking 1mA, the minimum output voltage is 50Ω • 1mA, or 50mV). See the graph “Headroom at Rev D 20 For more information www.analog.com LTC2636 OPERATION VREF = VCC POSITIVE FSE VREF = VCC OUTPUT VOLTAGE OUTPUT VOLTAGE INPUT CODE (c) OUTPUT VOLTAGE 0V NEGATIVE OFFSET 0V 0 2,048 INPUT CODE (a) 2636 F04 4,095 INPUT CODE (b) Figure 4. Effects of Rail-to-Rail Operation On a DAC Transfer Curve (Shown for 12 Bits). (a) Overall Transfer Function (b) Effect of Negative Offset for Codes Near Zero (c) Effect of Positive Full-Scale Error for Codes Near Full-Scale Rails vs. Output Current” in the Typical Performance Characteristics section. The amplifier is stable driving capacitive loads of up to 500pF. Rail-to-Rail Output Considerations In any rail-to-rail voltage output device, the output is limited to voltages within the supply range. Since the analog output of the DAC cannot go below ground, it may limit for the lowest codes as shown in Figure 4b. 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) is positive, the output for the highest codes limits at VCC, as shown in Figure 4c. 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. Board Layout The PC board should have separate areas for the analog and digital sections of the circuit. A single, solid ground plane should be used, with analog and digital signals carefully routed over separate areas of the plane. This keeps digital signals away from sensitive analog signals and minimizes the interaction between digital ground currents and the analog section of the ground plane. The resistance from the LTC2636 GND pin to the ground plane should be as low as possible. Resistance here will add directly to the effective DC output impedance of the device (typically 0.1Ω). Note that the LTC2636 is no more susceptible to this effect than any other parts of this type; on the contrary, it allows layout-based performance improvements to shine rather than limiting attainable performance with excessive internal resistance. Another technique for minimizing errors is to use a separate power ground return trace on another board layer. The trace should run between the point where the power supply is connected to the board and the DAC ground pin. Thus the DAC ground pin becomes the common point for analog ground, digital ground, and power ground. When the LTC2636 is sinking large currents, this current flows out the ground pin and directly to the power ground trace without affecting the analog ground plane voltage. It is sometimes necessary to interrupt the ground plane to confine digital ground currents to the digital portion of the plane. When doing this, make the gap in the plane only as long as it needs to be to serve its purpose and ensure that no traces cross over the gap. Rev D For more information www.analog.com 21 LTC2636 PACKAGE DESCRIPTION Please refer to http://www.linear.com/product/LTC2636#packaging for the most recent package drawings. DE Package 14-Lead Plastic DFN (4mm 3mm) (Reference LTC DWG # 05-08-1708 Rev B) 4.00 0.10 (2 SIDES) R = 0.05 TYP 0.70 0.05 3.30 0.05 3.60 0.05 2.20 0.05 PACKAGE OUTLINE 1.70 0.10 PIN 1 NOTCH R = 0.20 OR 0.35 45 CHAMFER PIN 1 TOP MARK (SEE NOTE 6) (DE14) DFN 0806 REV B 7 1 0.25 0.05 0.50 BSC 0.75 0.05 0.200 REF 0.25 0.05 0.50 BSC 0.40 0.10 14 3.30 0.10 3.00 0.10 (2 SIDES) 1.70 0.05 R = 0.115 TYP 8 3.00 REF 3.00 REF 0.00 – 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING PROPOSED TO BE MADE VARIATION OF VERSION (WGED-3) IN JEDEC PACKAGE OUTLINE MO-229 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 0.15mm ON ANY SIDE 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 MS Package 16-Lead Plastic MSOP (Reference LTC DWG # 05-08-1669 Rev A) 4.039 0.102 (.159 .004) (NOTE 3) 0.889 0.127 (.035 .005) 5.10 (.201) MIN 0.280 0.076 (.011 .003) REF 16151413121110 9 0.254 (.010) 3.20 – 3.45 (.126 – .136) DETAIL “A” 3.00 0.102 (.118 .004) (NOTE 4) 4.90 0.152 (.193 .006) 0 – 6 TYP GAUGE PLANE 0.305 0.038 (.0120 .0015) TYP 0.53 0.152 (.021 .006) 0.50 (.0197) BSC RECOMMENDED SOLDER PAD LAYOUT DETAIL “A” 0.18 (.007) SEATING PLANE 1.10 (.043) MAX 0.17 – 0.27 (.007 – .011) TYP 1234567 8 0.50 (.0197) BSC NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 0.86 (.034) REF 0.1016 0.0508 (.004 .002) MSOP (MS16) 0213 REV A Rev D 22 For more information www.analog.com LTC2636 REVISION HISTORY REV DATE DESCRIPTION A 12/09 Update Electrical Characteristics. B 06/10 PAGE NUMBER 5, 6, 8 Added details to Note 3. 9 Revised Typical Applications circuit. 24 C 05/17 Changed VCC slew rate number in Note 3. 9 D 04/18 Edits to Note 3. 9 Rev D Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license For is granted implication or otherwise under any patent or patent rights of Analog Devices. moreby information www.analog.com 23 LTC2636 TYPICAL APPLICATION LTC2636 DACs Adjust LTC2755-16 Offsets, Amplified with LT1991 PGA to ±5V 5V 15 15V 0.1µF 8 7 VDD LTC2755-16 + 5 IOUT1A 59 63 RCOM1 DAC A 1/2 LT1469 4 – IOUT2A 2 6 0.1µF 15V RFBA 60 0.1µF 61 ROFSA 64 RIN1 2 3 – 8 1/2 LT1469 + LT1634-1.25 DAC D 3 1 0.1µF LTC2636DE-LMI12 DAC A DAC H DAC B DAC G 13 – + DAC C DAC B 30k OUTB + – GND 1 P1 2 P3 3 P9 0.1µF 7 VCC LT1991 OUT 6 VOUT = ±5V REF VEE 5 4 0.1µF –15V 4 DAC C DAC F DAC D DAC E 11 –15V 5 30k 8 M9 9 M3 10 M1 12 LT1634-1.25 –15V LT1634-1.25 VCC LT1634-1.25 30k OUTC REF 0.1µF 2 30k –15V 5V 9 0.1µF –15V + – OUTD OUTA 4 –15V LT6240 15V 1 RVOSA 58 62 REFA + – 0.1µF 19 –15V SERIAL BUS 6 CS/LD 7 SCK 8 SDI 10 GND 14 2636 TA02 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC1660/LTC1665 Octal 10/8-Bit VOUT DACs in 16-Pin Narrow SSOP VCC = 2.7V to 5.5V, Micropower, Rail-to-Rail Output LTC1664 Quad 10-Bit VOUT DAC in 16-Pin Narrow SSOP VCC = 2.7V to 5.5V, Micropower, Rail-to-Rail Output LTC2600/LTC2610/ Octal 16-/14-/12-Bit VOUT DACs in 16-Lead Narrow SSOP LTC2620 250μA per DAC, 2.5V to 5.5V Supply Range, Rail-to-Rail Output, SPI Serial Interface LTC2601/LTC2611/ Single 16-/14-/12-Bit VOUT DACs in 10-Lead DFN LTC2621 300μA per DAC, 2.5V to 5.5V Supply Range, Rail-to-Rail Output, SPI Serial Interface LTC2602/LTC2612/ Dual 16-/14-/12-Bit VOUT DACs in 8-Lead MSOP LTC2622 300μA per DAC, 2.5V to 5.5V Supply Range, Rail-to-Rail Output, SPI Serial Interface LTC2604/LTC2614/ Quad 16-/14-/12-Bit VOUT DACs in 16-Lead SSOP LTC2624 250μA per DAC, 2.5V to 5.5V Supply Range, Rail-to-Rail Output, SPI Serial Interface LTC2605/LTC2615/ Octal 16-/14-/12-Bit VOUT DACs with I2C Interface LTC2625 250μA per DAC, 2.7V to 5.5V Supply Range, Rail-to-Rail Output, I2C Interface LTC2606/LTC2616/ Single 16-/14-/12-Bit VOUT DACs with I2C Interface LTC2626 270μA per DAC, 2.7V to 5.5V Supply Range, Rail-to-Rail Output, I2C Interface LTC2609/LTC2619/ Quad 16-/14-/12-Bit VOUT DACs with I2C Interface LTC2629 250μA per DAC, 2.7V to 5.5V Supply Range, Rail-to-Rail Output with Separate VREF Pins for Each DAC LTC2630 Single 12-/10-/8-Bit VOUT DACs with 10ppm/°C Reference in SC70 180μA per DAC, 2.7V to 5.5V Supply Range, 10ppm/°C Reference, Rail-to-Rail Output, SPI Interface LTC2631 Single 12-/10-/8-Bit I2C VOUT DACs with 10ppm/°C Reference in ThinSOT 180μA per DAC, 2.7V to 5.5V Supply Range, 10ppm/°C Reference, Selectable External Ref. Mode, Rail-to-Rail Output, I2C Interface LTC2640 Single 12-/10-/8-Bit VOUT DACs with 10ppm/°C Reference in ThinSOT 180μA per DAC, 2.7V to 5.5V Supply Range, 10ppm/°C Reference, Selectable External Ref. Mode, Rail-to-Rail Output, SPI Interface Rev D 24 D16868-0-5/18(D) www.analog.com  ANALOG DEVICES 2008-2018