ICmic TM ICM7912 12-BIT 125KSPS SAR ADC IC MICROSYSTEMS FEATURES • • • • • • • • • 12-Bit SAR ADC 125kSPS sampling rate Single supply single channel Low power dissipation 1.9mW Shutdown feature Flexible serial interface Supply voltage of 2.7V to 5.5V Temperature range: −40°C to +85°C 8-lead TSSOP APPLICATIONS • • • • • • PDA’s Touch screen monitors Hand held devices Instrumentation and control systems Data Acquisition Systems Automotive OVERVIEW The ICM7912 is a 12-bit 125kSPS through put rate Analog-to-Digital Converter with a unipolar, single-ended input. It has successive approximation register (SAR) architecture and can sample the analog input. It has a flexible serial interface. BLOCK DIAGRAM REFIN VIN ICM7912 R-DAC COMPARATOR C-DAC Successive Approximation Register (SAR) DOUT CSB Rev 0.1 DCLK BUSY ICmic reserves the right to change the specifications without prior notice. 1 ICmic TM ICM7912 12-BIT 125KSPS SAR ADC IC MICROSYSTEMS PACKAGE 8-Pin TSSOP VREF CSB AIN BUSY VDD DOUT GND DCLK PIN DESCRIPTION Pin No Symbol Description 1 2 3 4 5 6 7 8 VREF AIN VDD GND DCLK DOUT BUSY CSB Reference input Analog Input Power Supply Input. Range is from 2.7V to 5.5V Ground External CLK Input Serial Data output, clocked out on falling edge of CLK BUSY output Chip Select input Active Low. Initiates conversion and enables serial data. ABSOLUTE MAXIMUM RATING Symbol Parameter Value Unit VDD IIN VIN_ VIN_REF TSTG TSOL Supply Voltage Input Current Digital Input Voltage Reference Input Voltage Storage Temperature Soldering Temperature -0.3 to 6.0 +/- 100.0 -0.3 to 6.0 -0.3 to 6.0 -65 to +150 300 V mA V V o C o 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 ICM7912 Rev 0.1 Temperature Range o o -40 C to 85 C Package 8-Pin TSSOP ICmic reserves the right to change the specifications without prior notice. 2 ICmic TM ICM7912 12-BIT 125KSPS SAR ADC IC MICROSYSTEMS DC ELECTRICAL CHARACTERISTICS (VDD= 3.5V, Maximum Sample Rate, REF= 2.5V; all specifications TMIN to TMAX unless otherwise noted) Symbol Parameter Test Conditions Min Typ Max Unit DC PERFORMANCE N No Missing Codes INL GE OE VDD IVDD ISHTDOWN Symbol VIH VIL VOH VOL Fsample TCLK TDelay RIN IREF Resolution Integral Nonlinearity Gain Error Offset Error Supply Voltage Supply Current Supply Current Parameter (Note 1) 12 Bits (Note 1) 12 Bits (Note 1) (Note 1) (Note 1) POWER REQUIREMENTS (Note 2) (Note 1) (Note 1) Test Conditions 0.25 1 30 2.7 5.5 600 40 Min Typ Max 0.4 0.4 125 5 20 32 VDD 80 V µA µA LOGICINPUT/OUTPUT CHARACTERISTICS (VDD = 2.5V) 2.4 (Note 1) 2.4 IOH = 50 µΑ (Note 1) IOL = 50 µΑ SWITCHING SPECIFICATIONS (CLK INPUT) Maximum Conversion Rate (Note 2) Minimum Conversion Rate (Note 2) 0.5 CLK Period (Note 2) 500 Pulse-width High (Note 2) 250 Pulse-width Low (Note 2) 250 Data out Delay (Note 2) Wake-up Time (Note 2) REFERENCE Reference Input Resistance (Note 1) Reference Input Span Reference Input Current % of FSR % of FS mV Unit V V V V kSPS kSPS ns ns ns ns ms kΩ V µA Note 1: 100 % Production Tested at 25 C; guaranteed by design and characterization testing for temperature range. Note 2: Guaranteed by design& characterization testing. Note 3: See Applications Information. Note 4: 12 Monotonicity only guaranteed at REFIN MAX of VDD-1. Reference Input can swing to a higher value till VDD, with some degradation in DC performance and monotonicity could degrade to only 11 bits at high reference input. Rev 0.1 ICmic reserves the right to change the specifications without prior notice. 3 ICmic TM ICM7912 12-BIT 125KSPS SAR ADC IC MICROSYSTEMS TIMING DIAGRAM CSB 16 1 DCLK BUSY DOUT MSB DETAILED DESCRIPTION The ICM7912 is a SAR architecture 12-Bit ADC. It operates on a 2.7V to 5.5V single supply and consumes about 600µA supply current when operating on a 2MHz external clock. The output throughput rate is a maximum of 125 kSPS when the DCLK is running at at the maximum frequency of 2MHz. The ADC is composed of a high performance capacitive DAC and a comparator along with SAR control logic and resistor string segment. The reference input drives the resistor string directly and has an input resistance of around 32 kΩ. The ICM7912 comes complete with a high performance CMOS sample and hold amplifier made up by the capacitive DAC. LSB The ICM7912uses the DCLK as the external clock and this controls all the transfer of information to and from the ADC. One complete conversion cycle of the ICM7912 will take 16 clock cycles. As CSB is pulled low the ADC powers up and initiates a sampling/conversion cycle. Data is clocked out MSB first on the falling edge of the DCLK input. The analog input is sampled on the first three clock pulses and then conversion process begins. The DOUT is available from the falling edge of the 4th DCLK pulse MSB first and the LSB is available on the falling edge of the 15th DCLK pulse. Since there is some propagation delay the DOUT should be sampled on the rising edge of the following clock pulse. So this implies the MSB can be safely sampled on the 5th DCLK rising edge and the LSB can be sampled on the 16th DCLK rising edge. There is shutdown capability which is active between conversions when CSB is high. The converter will shut down to under 40 µA of supply current. APPLICATIONS INFORMATION The IC7912 has a single ended analog input which can swing from GND to VDD. The reference input has a range from GND to VDD and can be tied to VDD for largest input range. Rev 0.1 ICmic reserves the right to change the specifications without prior notice. 4 ICmic TM IC MICROSYSTEMS ICM7912 12-BIT 125KSPS SAR ADC PACKAGE INFORMATION 8 LEAD TSSOP STANDARD PACKAGE Rev 0.1 ICmic reserves the right to change the specifications without prior notice. 5