1 idt74fst3244 octal bus switch industrial temperature range april 2001 2001 integrated device technology, inc. dsc-5522/- c idt74fst3244 industrial temperature range octal bus switch description: the fst3244 belongs to idt's family of bus switches. bus switch devices perform the function of connecting or isolating two ports without providing any inherent current sink or source capability. thus they generate little or no noise of their own while providing a low resistance path for an external driver. these devices connect input and output ports through an n-channel fet. when the gate-to-source junction of this fet is adequately forward-biased the device conducts or the resistance between input and output ports is small. without adequate bias on the gate-to-source junction of the fet, the fet is turned off, therefore with no v cc applied, the device has hot insertion capability. the low on-resistance and simplicity of the connection between input and output ports reduces the delay in this path to close to zero. the fst3244 is an octal ttl-compatible bus switch. the oe pins provide output enable control for all 8 bits. this device is pin-compatible with and functionally similar to the fct244t. 1 oe 1 a 0 1 a 1 1 a 2 1 a 3 2 a 0 2 a 1 2 a 2 2 a 3 2 oe 2 b 0 2 b 1 2 b 2 2 b 3 1 b 0 1 b 1 1 b 2 1 b 3 5 6 7 8 9 10 1 2 3 4 18 17 16 15 14 13 12 11 gnd 1 a 0 2 b 3 1 a 1 1 oe 2 b 2 1 a 2 2 b 1 1 a 3 2 b 0 1 b 0 2 a 3 1 b 1 2 a 2 1 b 2 2 a 1 1 b 3 2 a 0 vcc 2 oe so20-2 so20-8 so20-9 so20-7 19 20 qsop/ soic/ ssop/ tssop top view functional block diagram pin configuration features: - bus switches provide zero delay paths - low switch on-resistance - ttl-compatible input and output levels - esd > 2000v per mil-std-883, method 3015; > 200v using machine model (c = 200pf, r = 0) - hot insertion capability - very low power dissipation - available in qsop, soic, ssop, and tssop packages
2 industrial temperature range idt74fst3244 octal bus switch capacitance (1) symbol parameter conditions (2) typ. unit c in control input capacitance 8 pf c i/o switch input/output capacitance switch off 13 pf notes: 1. capacitance is characterized but not tested. 2. t a = 25c, f = 1mhz, v in = 0v, v out = 0v absolute maximum ratings (1) symbol rating max. unit v term (2) terminal voltage with respect to gnd C0.5 to +7 v t stg storage temperature C65 to +150 c i out maximum continuous channel current 128 ma fst link notes: 1. stresses 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. 2. vcc, control, and switch terminals. pin description pin names description x oe output enable inputs (active low) xax a port bits xbx b port bits function table (1) 1 oe 2 oe description h h disconnect l h connect 1a to 1b h l connect 2a to 2b l l connect 1a to 1b and 2a to 2b note: 1. h = high l = low dc electrical characteristics over operating range following conditions apply unless otherwise specified: operating conditions: t a = -40c to +85c, v cc = 5.0v 5% symbol parameter test conditions min. typ. (1) max. unit v ih control input high voltage guaranteed logic high level 2 v v il control input low voltage guaranteed logic low level 0.8 v i ih control input high current v cc = max. v i = v cc 1a i il control input low current v i = gnd 1 i ozh current during v cc = max., v o = 0 to 5v 1 a i ozl bus switch disconnect 1 v ik clamp diode voltage v cc = min., i in = C18ma C0.7 C1.2 v i off switch power off leakage v cc = 0v, v in or v o 5.5v 1 a i cc quiescent power supply current v cc = max., v in = gnd or v cc 0.1 3a bus switch impedance over operating range following conditions apply unless otherwise specified: operating conditions: t a = -40c to +85c, v cc = 5.0v 5% symbol parameter test conditions min. typ. (1) max. unit r on switch connect resistance, a to b (2) vcc = min., v in = 0v i on = 30ma 5 7 w vcc = min., v in = 2.4v i on = 15ma 1015 i os short circuit current, a to b (3) a(b) = 0v, b(a) = v cc 100 ma notes: 1. typical values are at vcc = 5.0v, +25c ambient. 2. the voltage drop between the indicated ports divided by the current through the switch. 3. not more than one output should be shorted at one time. duration of the test should not esceed one second.
3 idt74fst3244 octal bus switch industrial temperature range notes: 1. for conditions shown as max. or min., use appropriate value specified under electrical characteristics for the applicable dev ice type. 2. typical values are at v cc = 5.0v, +25c ambient. 3. per ttl driven input (v in = 3.4v). all other inputs at v cc or gnd. 4. this parameter is not directly testable, but is derived for use in total power supply calculations. 5. c pd = i ccd /v cc c pd = power dissipation capacitance 6. i c = i quiescent + i inputs + i dynamic i c = i cc + d i cc d h n t + i ccd (f i n) i cc = quiescent current d i cc = power supply current for a ttl high input (v in = 3.4v) d h = duty cycle for ttl inputs high n t = number of ttl inputs at d h i ccd = dynamic current caused by an input transition pair (hlh or lhl) f i = input frequency n = number of switches toggling at f i all currents are in milliamps and all frequencies are in megahertz. notes: 1. see test circuit and waveforms. 2. the bus switch contributes no propagation delay other than the rc delay of the load interacting with the rc of the switch. 3. iq ci i is the charge injection for a single switch disconnect and applies to either single switches or multiplexers. iq dci i is the charge injection for a multiplexer as the multiplexed port switches from one path to another. charge injection is red uced becasue the injection from the disconnect of the first path is compensated by the connect of the second path. power supply characteristics symbol parameter test conditions (1) min. typ. (2) max. unit d i cc quiescent power supply current ttl inputs high v cc = max. v in = 3.4v (3) 0.51.5ma i ccd dynamic power supply current (4) v cc = max. outputs open v in = v cc v in = gnd 120 160 a/ mhz/ 1 enable pin toggling 50% duty cycle enable i c total power supply current (6) v cc = max. outputs open 2 enable pins toggling v in = v cc v in = gnd 2.43.2ma fi = 10mhz 50% duty cycle v in = 3.4 v in = gnd 2.94.7 switching characteristics over operating range following conditions apply unless otherwise specified: operating conditions: t a = -40c to +85c, v cc = 5.0v 5% symbol description min. (2) typ. max. unit t plh t phl data propagation delay a to b, b to a (2) 0.25 ns t pzh t pzl switch connect delay x oe to a or b 1.5 6.5 ns t phz t plz switch disconnect delay x oe to a or b 1.5 5.5 ns |q ci | charge injection during switch disconnect, x oe to a or b (3) 1.5pc
4 industrial temperature range idt74fst3244 octal bus switch d.u.t. v cc 1 mhz signal generator c l = 50pf (3) v out switch out enable/select switch in switch in (mux) (1) (2) pulse generator r t d.u.t. v cc v in c l v out 50pf 500 w 500 w 7.0v 3v 1.5v 0v 3v 1.5v 0v 3v 1.5v 0v 3v 1.5v 0v data input timing input asynchronous control synchronous control t su t h t rem t su t h high-low-high pulse low-high-low pulse t w 1.5v 1.5v same phase input transition 3v 1.5v 0v 1.5v v oh t plh output opposite phase input transition 3v 1.5v 0v t plh t phl t phl v ol control input 3v 1.5v 0v 3.5v 0v output normally low output normally high switch closed switch open v ol 0.3v 0.3v t plz t pzl t pzh t phz 3.5v 0v 1.5v 1.5v enable disable v oh test cir cuits and w a veforms propagation delay test circuits for all outputs enable and disable times set-up, hold, and release times pulse width notes: 1. diagram shown for input control enable-low and input control disable- high 2. pulse generator for all pulses: rate 1.0mhz; t f 2.5ns; t r 2.5ns switch position test switch open drain disable low closed enable low all other tests open fct link definitions: c l = load capacitance: includes jig and probe capacitance. r t = termination resistance: should be equal to z out of the pulse generator. charge injection notes: 1. select is used with multiplexers for measuring iq dci i during multiplexer select. during all other tests enable is used. 2. used with multiplexers to measure iq dci i only. 3. charge injection = d v out c l , with enable toggling for iq ci i or select toggling for iq dci i. d v out is the change in v out and is measured with a 10m w probe.
5 idt74fst3244 octal bus switch industrial temperature range corporate headquarters for sales: 2975 stender way 800-345-7015 or 408-727-6116 santa clara, ca 95054 fax: 408-492-8674 www.idt.com* *to search for sales office near you, please click the sales button found on our home page or dial the 800# above and press 2. the idt logo is a registered trademark of integrated device technology, inc. ordering information idt xx temp. range fst xx device type x package 244 8-bit switch 74 - 40 c to +85 c py so q pg shrink small outline package (so20-7) small outline ic (so20-2) quarter-size small outline package (so20-8) thin shrink small outline package (so20-9) family x 3 octal bus switch
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