ICM7372/7352/7332 ICmic DUAL 12/10/8-BIT VOLTAGE-OUTPUT DACS with Serial Interface and Adjustable Output Offset IC MICROSYSTEMS FEATURES • 12/10/8-Bit Monotonic Dual DAC in 16 Lead QSOP Package • Adjustable Output Offset • Wide Output Voltage Swing • 100 µA per DAC at 3V Supply • On Board Reference • Three-wire SPI/QSP and Microwire Interface Compatible • Serial Data Out for Daisy-Chaining • 8 µS Full scale Settling Time OVERVIEW The ICM7372, ICM7352 and ICM7332 are 12-Bit, 10-Bit and 8-Bit voltage output DACs respectively, with guaranteed monotonic behavior. These DACs are available in 16-pin QSOP package. They include adjustable output offset for ease of use and flexibility. The reference output is available on a separate pin and can be used to drive external loads. The operating supply range is 2.7V to 5.5V. The input interface is an easy to use three-wire SPI/QSPI and Microwire compatible interface. The DAC has a double buffered digital input for added flexibility. APPLICATIONS Battery-Powered Applications Industrial Process Control Digital Gain and Offset Adjustment BLOCK DIAGRAM REFB REFA ICM7372/7352/7332 DAC A INPUT AND DAC LATCH DAC B INPUT AND DAC LATCH REFERENCE + 50 KΩ VOA 50 KΩ OSA 50 KΩ VOB 50 KΩ OSB + - INPUT CONTROL LOGIC, REGISTERS AND LATCHES SDO SDI Rev. A10 SCK CS CLR ICmic reserves the right to change the specifications without prior notice. 1 ICM7372/7352/7332 ICmic DUAL 12/10/8-BIT VOLTAGE-OUTPUT DACS with Serial Interface and Adjustable Output Offset IC MICROSYSTEMS PACKAGE 16 Lead QSOP AGND 1 16 VDD VOA 2 15 VOB OSA 3 14 OSB REFA 4 13 REFB CLR 5 12 N/C CS 6 11 REFOUT SDI 7 10 SDO SCK 8 9 DGND TOP VIEW PIN DESCRIPTION (16 Lead QSOP) Pin Name I/O Description 1 AGND I Analog Ground 2 VOA O DAC A Output Voltage 3 OSA I DAC A Offset Adjustment 4 REFA I Reference Voltage Input to DAC A 5 CLR I Active Low Clear Input (CMOS). Resets All Registers to Zero. DAC outputs go to 0 V 6 CS I Active Low Chip Select (CMOS) 7 SDI I Serial Data Input (CMOS) 8 SCK I Serial Clock Input (CMOS) 9 DGND I Digital Ground 10 SDO O Serial data Output 11 REFOUT O Reference Output 12 N/C - No Connection 13 REFB I Reference Voltage Input to DAC B 14 OSB I DAC B Offset Adjustment 15 VOB O DAC B Output Voltage 16 VDD I Supply Voltage Rev. A10 ICmic reserves the right to change the specifications without prior notice. 2 ICM7372/7352/7332 ICmic DUAL 12/10/8-BIT VOLTAGE-OUTPUT DACS with Serial Interface and Adjustable Output Offset IC MICROSYSTEMS ABSOLUTE MAXIMUM RATING Symbol Parameter Value Unit VDD Supply Voltage -0.3 to 7.0 V IIN Input Current +/- 25.0 mA VIN_ Digital Input Voltage (SCK, SDI , CLR , CS ) -0.3 to 7.0 V VIN_REF Reference Input Voltage -0.3 to 7.0 V TSTG Storage Temperature -65 to +150 o 300 o TSOL Soldering Temperature C C Note: Stress greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability. ORDERING INFORMATION Part Operating Temperature Range Package ICM7372 -40 oC to 85 oC 16-Pin QSOP ICM7352 -40 oC to 85 oC 16-Pin QSOP o ICM7332 o -40 C to 85 C 16-Pin QSOP DC ELECTRICAL CHARACTERISTICS (VDD = 2.7V to 5.5V, VOUT unloaded; all specifications TMIN to TMAX unless otherwise noted) Symbol Parameter Test Conditions Min Typ. Max Unit DC PERFORMANCE ICM7372 N Resolution 12 Bits DNL Differential Nonlinearity (Notes 1 & 3) 0.4 +1.0 LSB INL Integral Nonlinearity (Notes 1 & 3) 4.0 +12.0 LSB ICM7352 N Resolution DNL Differential Nonlinearity (Notes 1 & 3) 10 0.1 +1.0 Bits LSB INL Integral Nonlinearity (Notes 1 & 3) 1.0 +3.0 LSB ICM7332 N Resolution 8 Bits DNL Differential Nonlinearity (Notes 1 & 3) 0.05 +1.0 LSB INL Integral Nonlinearity (Notes 1 & 3) 0.25 +0.75 LSB GE Gain Error +0.5 % of FS OE Offset Error +25 mV 5.5 V 1.5 mA POWER REQUIREMENTS VDD Supply Voltage IDD Supply Current Rev. A10 2.7 (Note 4) 0.6 ICmic reserves the right to change the specifications without prior notice. 3 ICM7372/7352/7332 ICmic DUAL 12/10/8-BIT VOLTAGE-OUTPUT DACS with Serial Interface and Adjustable Output Offset IC MICROSYSTEMS Symbol Parameter Test Conditions Min Typ. Max Unit OUTPUT CHARACTERISTICS Output Voltage Range (Note 3) 0 VDD Short Circuit Current VOSC ROUT V 60 150 mA Amp Output Impedance At Mid-scale (Note 2) At 0-scale (Note 2) 1.0 100 5.0 200 Ω Ω Output Line Regulation VDD=2.7 to 5.5 V 0.4 3.0 mV/V LOGIC INPUTS VIH Digital Input High (Note 2) VIL Digital Input Low (Note 2) 2.4 V 0.8 V 5 µΑ 1.25 1.3 V 0.8 4.0 mV/V Digital Input Leakage REFERENCE VREFOUT Reference Output 1.2 Reference Output Line Regulation AC ELECTRICAL CHARACTERISTICS (VDD = 2.7V to 5.5V, VOUT unloaded; all specifications TMIN to TMAX unless otherwise noted) Symbol SR Parameter Test Conditions Min Slew Rate Full-scale settling Unit V/µs 8 Mid-scale Transition Glitch Energy Note 2: Note 3: Note 4: Max 2 Settling Time Note 1: Typ. µs nV-S 40 Linearity is defined from code 64 to 4095 (ICM7372) Linearity is defined from code 16 to 1023 (ICM7352) Linearity is defined from code 4 to 255 (ICM7332) Guaranteed by design; not tested in production See Applications Information All digital Inputs at GND or VDD TIMING CHARACTERISTICS (VDD = 2.7V to 5.5V, all specifications TMIN to TMAX unless otherwise noted) Symbol Parameter Test Conditions Min Typ Max Unit t1 SCK Cycle Time (Note 2) 30 ns t2 Data Setup Time (Note 2) 10 ns t3 Data Hold Time (Note 2) 10 ns t4 SCK Falling edge to CS Rising Edge (Note 2) 0 ns t5 CS Falling Edge to SCK Rising Edge (Note 2) 15 ns t6 CS Pulse Width (Note 2) 20 ns t7 SDO Delay (Note 2) Rev. A10 ICmic reserves the right to change the specifications without prior notice. 100 ns 4 ICM7372/7352/7332 ICmic DUAL 12/10/8-BIT VOLTAGE-OUTPUT DACS with Serial Interface and Adjustable Output Offset IC MICROSYSTEMS t1 SCK t3 t2 SDI C3 C2 LSB t5 Input Word for DAC N t4 CS t6 t7 SDO C3 C2 Input Word for DAC N Figure 1. Serial Interface Timing Diagram Rev. A10 ICmic reserves the right to change the specifications without prior notice. 5 ICM7372/7352/7332 ICmic DUAL 12/10/8-BIT VOLTAGE-OUTPUT DACS with Serial Interface and Adjustable Output Offset IC MICROSYSTEMS CS (ENABLE SCK) (UPDATE OUTPUT) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 C3 C2 C1 C0 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 SCK SDI CONTROL WORD DATA WORD INPUT WORD W 0 SDO C3 C2 C1 C0 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 INPUT WORD W -1 C3 INPUT WORD W 0 Figure 2. Serial Interface Operation Diagram Rev. A10 ICmic reserves the right to change the specifications without prior notice. 6 ICM7372/7352/7332 ICmic DUAL 12/10/8-BIT VOLTAGE-OUTPUT DACS with Serial Interface and Adjustable Output Offset IC MICROSYSTEMS CONTENTS OF INPUT SHIFT REGISTER ICM7372 (12-Bit DAC) MSB C3 LSB C2 C1 C0 D11 D10 D9 D8 D7 CONTROL WORD D6 D5 D4 D3 D2 D1 D0 DATA WORD Figure 3. Contents of ICM7372 Input Shift Register ICM7352 (10-Bit DAC) MSB C3 LSB C2 C1 C0 D9 D8 D7 D6 CONTROL WORD D5 D4 D3 D2 D1 D0 DATA WORD X X X X Figure 4. Contents of ICM7352 Input Shift Register ICM7332 (8-Bit DAC) MSB C3 LSB C2 C1 C0 D7 D6 CONTROL WORD D5 D4 D3 D2 D1 D0 DATA WORD X X X X X X X X Figure 5. Contents of ICM7332 Input Shift Register C3 C2 C1 C0 DATA (D11 – D0) FUNCTION 0 0 0 0 Data Load Input Latch DAC A 0 0 0 1 Data Update DAC A 0 0 1 0 Data Load Input Latch and Update DAC A 0 0 1 1 Data Load Input Latch DAC B 0 1 0 0 Data Update DAC B 0 1 0 1 Data Load Input Latch and Update DAC B 0 1 1 0 X No Operation 0 1 1 1 X No Operation 1 0 0 0 X No Operation 1 0 0 1 X No Operation 1 0 1 0 X No Operation 1 0 1 1 X No Operation 1 1 0 0 Data Load Input Latch All DACs 1 1 0 1 Data Update DAC All DACs 1 1 1 0 Data Load Input Latch and Update All DACs 1 1 1 1 X No Operation Table 1. Serial Interface Input Word Rev. A10 ICmic reserves the right to change the specifications without prior notice. 7 ICM7372/7352/7332 ICmic IC MICROSYSTEMS DETAILED DESCRIPTION The ICM7372 is a 12-bit voltage output dual DAC. The ICM7352 is the 10-bit version of this family and the ICM7332 is the 8-bit version. These devices have a 16-bit data-in/data-out shift register and double buffered input. The amplifier’s offset adjustment pins allow for a DC shift in the DAC’s output. This family of DACs employs a resistor string architecture guaranteeing monotonic behavior. There is a 1.25V onboard reference and an operating supply range of 2.7V to 5.5V. Reference Input Each DAC has its own reference input pin which can be driven from ground to VDD -1.5V. Determine the output voltage using the following equation when output adjustment pin, OSA or OSB is connected to ground 0V. VOUT = 2 x (VREF x (D / (2n))) Where D is the numeric value of DAC’s decimal input code, VREF is the reference voltage and n is number of bits, i.e. 12 for ICM7372, 10 for ICM7352 and 8 for ICM7332. Reference Output The reference output is nominally 1.25V and is brought out to a separate pin and can be used to drive external loads. The outputs will nominally swing from 0 to 2.5V when using this reference. DUAL 12/10/8-BIT VOLTAGE-OUTPUT DACS with Serial Interface and Adjustable Output Offset The Chip Select pin which is the 6th pin of 16 QSOP package is active low. This pin must be low when data is being clocked into the part. After the 16th clock pulse the Chip Select pin must be pulled high (level-triggered) for the data to be transferred to an input bank of latches. This pin also disables the SCK pin internally when pulled high and the SCK pin must be low before this pin is pulled back low. As the Chip Select pin is pulled high the shift register contents are transferred to a bank of 16 latches (see Figure 2.). The 4 bit control word (C3~C0) is then decoded and the DAC is updated or loaded depending on the control word (see Table 1). The DAC has a double-buffered input with an input latch and a DAC latch. The DAC output will swing to its new value when data is loaded into the DAC latch. The user has three options: loading only the input latch, updating the DAC with data previously loaded into the input latch or loading the input latch and updating the DAC at the same time with a new code. Serial Data Output SDO (Serial Data Output) is the internal shift register’s output. This pin can be used as the data output pin for Daisy-Chaining and data readback. It is compatible with SPI/QSPI and Microwire interfaces. Power-On Reset There is a power-on reset on board that will clear the contents of all the latches to all 0s on power-up and the DAC voltage output will go to ground. APPLICATIONS INFORMATION Output Amplifier The Dual DAC has 2 output amplifiers with a wide output voltage swing. The actual swing of the output amplifiers will be limited by offset error and gain error. See the Applications Information Section for a more detailed discussion. The offset adjustment pins, either OSA or OSB can be used to produce an adjustable offset voltage at the output. For instance, to achieve a 1V offset, apply -1V to the offset adjustment pin to produce an output range from 1V to (1V + VREF x 2). Note that the DAC’s output range is still limited by offset error and gain error. See the Applications Information Section for a more detailed discussion. The output amplifier can drive a load of 2.0 kΩ to VDD or GND in parallel with a 500 pF load capacitance. The output amplifier has a full-scale typical settling time of 8 µs and it dissipates about 100 µA with a 3V supply voltage. Serial Interface and Input Logic This dual DAC family uses a standard 3-wire connection compatible with SPI/QSPI and Microwire interfaces. Data is loaded in 16-bit words which consist of 4 address and control bits (MSBs) followed by 12 bits of data (see table 1). The ICM7352 has the last 2 LSBs as don’t care and the ICM7332 has the last 4 LSBs as don’t care. The DAC is double buffered with an input latch and a DAC latch. Power Supply Bypassing and Layout Considerations As in any precision circuit, careful consideration has to be given to layout of the supply and ground. The return path from the GND to the supply ground should be short with low impedance. Using a ground plane would be ideal. The supply should have some bypassing on it. A 10 µF tantalum capacitor in parallel with a 0.1 µF ceramic with a low ESR can be used. Ideally these would be placed as close as possible to the device. Avoid crossing digital and analog signals, specially the reference, or running them close to each other. Output Swing Limitations The ideal rail-to-rail DAC would swing from GND to VDD. However, offset and gain error limit this ability. Figure 6 illustrates how a negative offset error will affect the output. The output will limit close to ground since this is single supply part, resulting in a dead-band area. As a larger input is loaded into the DAC the output will eventually rise above ground. This is why the linearity is specified for a starting code greater than zero. Figure 7 illustrates how a gain error or positive offset error will affect the output when it is close to VDD. A positive gain error or positive offset will cause the output to be limited to the positive supply voltage resulting in a deadband of codes close to full-scale. Serial Data Input SDI (Serial Data Input) pin is the data input pin for all DACs. Data is clocked in on the rising edge of SCK which has a Schmitt trigger internally to allow for noise immunity on the SCK pin. This specially eases the use for optocoupled interfaces. Rev. A10 ICmic reserves the right to change the specifications without prior notice. 8 ICM7372/7352/7332 ICmic DUAL 12/10/8-BIT VOLTAGE-OUTPUT DACS with Serial Interface and Adjustable Output Offset IC MICROSYSTEMS DEADBAND NEGATIVE OFFSET Figure 6. Effect of Negative Offset OFFSET AND GAIN ERROR VDD DEADBAND POSITIVE OFFSET Figure 7. Effect of Gain Error and Positive Offset Rev. A10 ICmic reserves the right to change the specifications without prior notice. 9 ICM7372/7352/7332 ICmic IC MICROSYSTEMS DUAL 12/10/8-BIT VOLTAGE-OUTPUT DACS with Serial Interface and Adjustable Output Offset PACKAGE INFORMATION Rev. A10 ICmic reserves the right to change the specifications without prior notice. 10 ICM7372/7352/7332 ICmic DUAL 12/10/8-BIT VOLTAGE-OUTPUT DACS with Serial Interface and Adjustable Output Offset IC MICROSYSTEMS ORDERING INFORMATION ICM73X2 P G Device 7 - ICM7372 5 - ICM7352 3 - ICM7332 Rev. A10 G = RoHS Compliant Lead-Free package. Blank = Standard package. Non lead-free. Package Q = 16-Lead QSOP ICmic reserves the right to change the specifications without prior notice. 11