ic microsystems ic mic tm ic microsystems ic mic tm ICM7912 12- bit 125 k sps sar adc rev 0.1 icmic reserves the right to change the spec ifications without prior notice. 1 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: ?40c to +85c ? 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 dout ICM7912 comparator c - dac dclk refin csb vin successive approximation register (sar) r-dac busy
ic microsystems ic mic tm ic microsystems ic mic tm ICM7912 12- bit 125 k sps sar adc rev 0.1 icmic reserves the right to change the spec ifications without prior notice. 2 package 8-pin tssop pin description pin no symbol description 1 vref reference input 2 ain analog input 3 vdd power supply input. range is from 2.7v to 5.5 v 4 gnd ground 5 dclk external clk input 6 dout serial data output, clocked out on falling edge of clk 7 busy busy output 8 csb chip select input active low. initiates conversion and enables serial data. absolute maximum rating symbol parameter value unit v dd supply voltage -0.3 to 6.0 v i in input current +/- 100.0 ma v in_ digital input voltage -0.3 to 6.0 v v in_ref reference input voltage -0.3 to 6.0 v t stg storage temperature -65 to +150 o c t sol soldering temperature 300 o c note : stress greater than those listed under absolute m aximum 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 cond itions above those indicated in the operational sections of this speci fication is not implied. exposure to absolute maxim um rating conditions for extended periods may affect reliability . ordering information part temperature range package ICM7912 -40 o c to 85 o c 8-pin tssop csb busy dout dclk vref ain vdd gnd
ic microsystems ic mic tm ic microsystems ic mic tm ICM7912 12- bit 125 k sps sar adc rev 0.1 icmic reserves the right to change the spec ifications without prior notice. 3 dc electrical characteristics (vdd= 3.5v, maximum sample rate, ref = 2.5v; all specifications t min to t max unless otherwise noted) symbol parameter test conditions min typ max unit dc performance n resolution (note 1) 12 bits no missing codes (note 1) 12 bits inl integral nonlinearity (note 1) 0.25 % of fsr ge gain error (note 1) 1 % of fs oe offset error (note 1) 30 mv power requirements vdd supply voltage (note 2) 2.7 5.5 v i vdd supply current (note 1) 600 a i shtdown supply current (note 1) 40 a symbol parameter test conditions min typ max unit logicinput/output characteristics (vdd = 2.5v) vih 2.4 v vil 0.4 v voh ioh = 50 ? (note 1) 2.4 v vol iol = 50 ? (note 1) 0.4 v switching specifications (clk input) fsample maximum conversion rate (note 2) 125 ksps minimum conversion rate (note 2) 0.5 ksps tclk clk period (note 2) 500 ns pulse-width high (note 2) 250 ns pulse-width low (note 2) 250 ns t delay data out delay (note 2) 5 ns wake-up time (note 2) 20 ms reference r in reference input resistance (note 1) 32 k reference input span vdd v i ref reference input current 80 a note 1: 100 % production tested at 25 c; guarantee d by design and characterization testing for temper ature 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 highe r value till vdd, with some degradation in dc performance and mo notonicity could degrade to only 11 bits at high re ference input.
ic microsystems ic mic tm ic microsystems ic mic tm ICM7912 12- bit 125 k sps sar adc rev 0.1 icmic reserves the right to change the spec ifications without prior notice. 4 timing diagram 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 600 a 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 k . the ICM7912 comes complete with a high performance cmos sample and hold amplifier made up by the capacitive dac. there is shutdown capability which is active between conversions when csb is high. the converter will shut down to under 40 a 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. 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 4 th dclk pulse msb first and the lsb is available on the falling edge of the 15 th 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 5 th dclk rising edge and the lsb can be sampled on the 16 th dclk rising edge. 1 16 msb lsb csb dclk dout busy
ic microsystems ic mic tm ic microsystems ic mic tm ICM7912 12- bit 125 k sps sar adc rev 0.1 icmic reserves the right to change the spec ifications without prior notice. 5 package information 8 lead tssop standard package
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