serialcoder? ir UR5HC703-IR20 extremely low-power keyboard encoder interfaces irda serialcoder is a trademark of semtech corporation. all other trademarks belong to their respective companies. copyright ?1999-2001 semtech corporation doc5-703-ir20-ds-101 www.semtech.com 1 hid & system management products, keycoder? family description features 1 8 9 32 25 24 16 17 col3 col4 col5 col6 vdd2 reset vss2 vdd row6 row5 row4 row3 row2 row1 row0 col15 ocsin oscout vss col7 col8 col9 col10 col11 row7 col12 txd col13 col14 col0 col1 col2 UR5HC703-IR20-fg lqfp ? 8 x 16 matrix encoding ic is independent of the keyboard layout extremely low-power operation, transparent to the host typical current consumption of less than 1a at room temperature; 10a at 85c robust algorithm for ghost-key elimination cmos output-only asynchronous serial interface to the host using standard irda 9600 baud 8n1 serial data format very simple serial protocol ? two- byte identification string on power-up; single-byte matrix- position for each key-press or key-release low-cost wireless keyboard solution the serialcoder? ir ur5hc703- ir20 is an extremely low-power, ?off- the-shelf? infrared serial keyboard encoder. robust, tiny and flexible, the ic is a good match for any application where a low-cost wireless keyboard is attractive and an irda host is available. the ic provides extremely low- power operation, transparent to the host. power consumption is reduced to just the circuit?s leakage when all keys are released. the typical current consumption is less than 1a at room temperature and 10a at 85c. if a key or group of keys stays in the depressed position for ten minutes (with no other keyboard activity), the ic shuts down to save power. the serialcoder? ir is simple to implement. it requires few external components and utilizes a tiny, low- profile 32-pin lqfp package that measures 7mm x 7mm. applications infrared wireless keyboards personal digital assistant (pda) keyboard instrumentation remote control home entertainment or automation pin assignments preliminary
serialcoder? ir UR5HC703-IR20 functional diagram ordering code copyright ?1999-2001 semtech corporation doc5-703-ir20-ds-101 www.semtech.com 2 txd 4 data buffer key matrix interface communication interface matrix scan logic reset logic oscillator power supply _reset oscin _oscout 8 16 r0-r7 c0-c15 package options pitch ta = -20 c to +85 c 32-pin plastic lqfp 0.8 mm UR5HC703-IR20-fg other materials type order number UR5HC703-IR20 eval. kit evaluation kit evk5-703-ir20
pin definitions copyright ?1999-2001 semtech corporation doc5-703-ir20-ds-101 www.semtech.com 3 mnemonic pin # type name and function power supply v dd , v dd 2 8,5 pwr positive supply voltage v ss , v ss 2 11,7 pwr negative power supply : signal ground reset _reset 6 i hardware reset pin : reset input for orderly start-up. low logic level is required whenever v dd is below minimum operating voltage oscillator pins oscin 9 i oscillator input : connect ceramic resonator with built-in load capacitors or cmos clock from external oscillator 2 mhz operating frequency _oscout 10 o oscillator output : connect ceramic resonator with built-in load capacitors or keep open if external oscillator is used host interface txd 27 o serial data output : idle at high voltage (logical 1), non-inverted data; 4s pulsed output per irda timing specification scanned matrix pins row0-row7 18-25 i row matrix inputs with pulsed pull-up current sources col0-col15 30-32, o column matrix output , open drain 1-4, 12-16, 26, 28, 29, 17 note: an underscore before a pin mnemonic denotes an active low signal.
copyright ?1999-2001 semtech corporation doc5-703-ir20-ds-101 www.semtech.com 4 ?ghost? keys in any scanned contact switch matrix, whenever three keys defining a rectangle on the switch matrix are pressed at the same time, a fourth key positioned on the fourth corner of the rectangle is sensed as being pressed. this is known as the ?ghost? or ?phantom? key problem. figure 1 : ?ghost? or ?phantom? key problem although the problem cannot be totally eliminated without using external hardware, there are methods to neutralize its negative effects for most practical applications. keys that are intended to be used in combinations should be placed in the same row or column of the matrix, whenever possible. shift keys (shift, alt, ctrl, window) should not reside in the same row (or column) as any other keys. the serialcoder? ir has built-in mechanisms to detect the presence of ?ghost? keys. actual key presses ?ghost? key keyboard scanner the encoder scans a keyboard organized as an 8 row by 16 column matrix for a maximum of 128 keys. smaller size matrixes can also be accommodated by simply leaving unused pins open. the serialcoder? ir provides internal pull-ups for the row input pins. when active, the encoder selects one of the column lines (c0-c15) every 512 s and then reads the row data lines (r0-r7). a key closure is detected as a zero in the corresponding position of the matrix. a complete scan cycle for the entire keyboard takes approximately 9.2 ms. each key found pressed is debounced for a period of 20 ms. once the key is verified, the corresponding key code(s) are loaded into the transmit buffer of the serial communication channel. n-key rollover means the code(s) corresponding to each key press are transmitted to the host system as soon as that key is debounced, indepen- dent of the release of other keys. when a key is released, the corresponding break code is transmitted to the host system. several keys can be held pressed at the same time. however, if two or more key closures occur within a time interval of less than 5 ms, an error flag is set, and those closures are not processed. this feature protects against the effects of accidental key presses. the serialcoder? ir achieves uniquely low system power consumption thanks to self-power management?, which powers down the ic between key presses. a key press wakes up the ic immediately without losing any key data. n-key rollover power management
protocol copyright ?1999-2001 semtech corporation doc5-703-ir20-ds-101 www.semtech.com 5 serial transmission rate is 9600 baud, with 8 data bits, no parity, least significant bits transmitted first, idle/stop level high (logical 1), start bit level low (logical 0), non-inverted data. each bit with a zero value, including the start bit, is indicated by a four-microsecond low pulse of the txd line toward the beginning of the time slot for the bit. infrared signals are based on the infrared data association (irda) serial infrared physical layer specification . the diagram below shows the electrical wave form of a single transmitted byte, 0x65. (note that pulse width is not to scale.) within 5ms after power-up, the ic sends a two-byte identification string of 0xf9, 0xfb. these two bytes are transmitted only once after each power-up or reset of the ic. these two id values also represent key release action in the locations [row=1, column=15] and [row=3, column=15] on the key matrix. since the values of these bytes represent release action of the keys, extraneous characters are never generated, even if synchronization between the driver and ic is lost, or power fluctuations/erroneous resets are applied to the chip. if logistics of the host software driver do not permit "shared" use of the identification values 0xf9 and 0xfb, then the user is advised not to incorporate keys in the locations [row=1, column=15] and [row=3, column=15] for the key matrix design. subsequent single-byte transmissions indicate the row (0-7), column (0-15), and press/release action for each change of the state of every key. if the release of a key leaves all of the keys on the key matrix in the released state, the release report for that key is sent twice. two release report bytes in a row for the same key are a signal to the host driver that the keyboard is completely idle and all keys are up. keyboard report byte bit number b7 b6 b5 b4 b3 b2 b1 b0 comment 0 for key press (make), 1 for key release (break) column location in the key matrix 4-bit binary value (0-15) row location in the key matrix (0-7) 3-bit binary value (0-7) 0 start 1 data 0 data 1 data 0 data 0 data 1 data 1 data 0 data 1 stop
sample schematic for the serialcoder? ir UR5HC703-IR20-fg copyright ?1999-2001 semtech corporation doc5-703-ir20-ds-101 www.semtech.com 6 power partial bom y1 = pbrc-2.00 br (avx), cstc2.00mg (murata) u2 = mn1382e (panasonic), tc54vc2402ecb (microchip) direct ired drive d2 ired to keyboard matrix c 3 1 c 4 2 c 5 3 c 6 4 v d d 2 5 r e s e t 6 v s s 2 7 v d d 8 oscin 9 oscout 10 vss 11 c7 12 c8 13 c9 14 c10 15 c11 16 c 1 5 1 7 r 0 1 8 r 1 1 9 r 2 2 0 r 3 2 1 r 4 2 2 r 5 2 3 r 6 2 4 r7 25 c12 26 txd 27 c13 28 c14 29 c0 30 c1 31 c2 32 u1 UR5HC703-IR20-fg 32-pin lqfp r2 100 c3 330f q1 mosfet_p r1 12 long-range driver ground gnd d1 ired y1 2.00mhz gnd gnd c2 1.0f 10v c1 0.1f gnd gnd gnd out 1 gnd 3 vdd 2 u2 voltage detector 2.2v or higher note: the circuit segment connecting to ground through c2 is used only for direct ired drive. note: the p-channel mosfet (q1) should ideally have rds < 0.5 ohms, e.g. nds356p (digikey). a standard mosfet can be used, e.g. bss84 (digikey), but the active range of the infrared is reduced. note: the infrared-emitting diode (d1 or d2) should be chosen to match the receiver. if the receiver is not known, a standard irda-compatible led should be used, with a wavelength of 850nm to 900nm, e.g. pdi-e802 (digikey). for irda specifications, refer to the infrared data association (irda) s erial infrared physical layer specification .
serialcoder? ir UR5HC703-IR20-fg electrical characteristics copyright ?1999-2001 semtech corporation doc5-703-ir20-ds-101 www.semtech.com 7 absolute maximum ratings ratings symbol value unit (vss = 0v, ambient temperature t a is in the range t low to t high ) supply voltage v dd -0.3 to +7.0 v input voltage: all input pins v in -0.3 to v dd +0.3 v output current: total peak for all pins i oh (peak) -80 i ol (peak) 80 ma total average for all pins i oh (avg) -40 i ol (avg) 40 ma peak for each pin i oh (peak) -10 i ol (peak) 10 ma average for each pin i oh (avg) -5 i ol (avg) 5 ma temperature range operating temperature t low to t high -20 to 85 c storage temperature t stg -40 to 125 c esd rating (human body model) v esd 2.0 kv dc electrical characteristics, temperature range=t low to t high unless otherwise noted) characteristic symbol min typ max unit operating voltage v dd 2.2 5.5 v input voltage high v ih 0.8 v dd v dd v l ow v il 0 0.3 v dd v v il (_reset) 0 0.2 v dd v v il (oscin) 0 0.16 v dd v input current high l ih 5.0 a l ih (oscin) 4.0 a input current low i il -5.0 a i il (oscin) -4.0 a output voltage v oh i oh =-1.0ma v dd -1.0 v dd v v ol i ol =1.0ma 1.0 v power consumption o ne or more keys are depressed i dd 1.5 ma a ll keys are released ta=25c i dd 0.1 1.0 a ta=85c i dd 10.0 a control timing (vdd=2.2 to 5.5 v, vss=0 vdc, temperature range=t low to t high unless otherwise noted) characteristic symbol value unit frequency of operations ceramic resonator with built-in load fosc 2.0 mhz capacitors transmit pulse 4 s note: communications baud rate and active-state power consumption are scaled linearly with operating frequency. higher operating frequencies are possible within a reduced operating voltage range. consult semtech for further information.
mechanicals for the serialcoder? ir UR5HC703-IR20-fg lqfp package copyright ?1999-2001 semtech corporation doc5-703-ir20-ds-101 www.semtech.com 8 a e f b y c a 1 a 2 l 1 l detail f e m d m e b 2 i 2 recommended pcb footprint ? 0.1 ? ?? 0.2 ? ? ?? ? ? ? ? ? symbol min nom max a a 2 b c d e h e l l 1 y b 2 dimension in millimeters h d a 1 0.5 ? ? i 2 1.0 ? ? m d 7.4 ? ? m e 7.4 10 ? 0 ? 0.1 1.0 0.7 0.5 0.3 9.2 9.0 8.8 9.2 9.0 8.8 0.8 7.1 7.0 6.9 7.1 7.0 6.9 0.175 0.125 0.105 0.45 0.35 0.3 1.4 0 1.7 e e h e 1 8 9 32 25 24 16 17 h d d
copyright ?1999-2001 semtech corporation doc5-703-ir20-ds-101 www.semtech.com 9 this page left intentionally blank
copyright ?1999-2001 semtech corporation doc5-703-ir20-ds-101 www.semtech.com 10 for sales information and product literature, contact: hid & system mgmt division semtech corporation 652 mitchell road newbury park, ca 91320 hidinfo@semtech.com http://www.semtech.com/ 805 498 2111 telephone 805 498 3804 telefax semtech western regional sales 805-498-2111 telephone 805-498-3804 telefax semtech central regional sales 972-437-0380 telephone 972-437-0381 telefax semtech eastern regional sales 203-964-1766 telephone 203-964-1755 telefax semtech asia-pacific sales office +886-2-2748-3380 telephone +886-2-2748-3390 telefax semtech japan sales office +81-45-948-5925 telephone +81-45-948-5930 telefax semtech korea sales sales +82-2-527-4377 telephone +82-2-527-4376 telefax northern european sales office +44 (0)2380-769008 telephone +44 (0)2380-768612 telefax southern european sales office +33 (0)1 69-28-22-00 telephone +33 (0)1 69-28-12-98 telefax central european sales office +49 (0)8161 140 123 telephone +49 (0)8161 140 124 telefax copyright ?1999-2001 semtech corporation. all rights reserved. serialcoder and keycoder are trademarks of semtech corporation. semtech is a registered trademark of semtech corporation. all other trademarks belong to their respective companies. intellectual property disclaimer this specification is provided "as is" with no warranties whatsoever including any warranty of merchantability, fitness for any particular purpose, or any warranty otherwise arising out of any proposal, specification or sample. a license is hereby granted to reproduce and distribute this specification for internal use only. no other license, expressed or implied to any other intellectual property rights is granted or intended hereby. authors of this specification disclaim any liability, including liability for infringement of proprietary rights, relating to the implementation of information in this specification. authors of this specification also do not warrant or represent that such implementation(s) will not infringe such rights.
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