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Part: M3004LD
Category:
Analog & Mixed-Signal Processing
Description: RC Transmitter 64 Commands
Company: ST Microelectronics, Inc.
Datasheet: Download M3004LD datasheet File size : 54 kB
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Datasheet text preview:
M3004LAB1 M3004LD
REMOTE CONTROL TRANSMITTER
. . . . . . . . . .
FLASHED OR MODULATED TRANSMISSION 7 SUB-SYSTEM ADDRESSES UP TO 64 COMMANDS PER SUB-SYSTEM ADDRESS HIGH-CURRENT REMOTE OUTPUT AT VDD = 6V ( IOH = 80mA) LOW NUMBER OF ADDITIONAL COMPONENTS KEY RELEASE DETECTION BY TOGGLE BITS VERY LOW STAND-BY CURRENT (< 2ľA) OPERATIONAL CURRENT < 1mA AT 6V SUPPLY SUPPLY VOLTAGE RANGE 2 TO 6.5V CERAMIC RESONATOR CONTROLLED FREQUENCY (typ. 450kHz)
DIP20 (Plastic Pack age) ORDER CODE : M3004LAB1
SO20 (Plastic Pack age) ORDER CODE : M3004LD
PIN CONNECTIONS
REMO
1 2 3 4 5 6 7 8 9 10
20 19
DESCRIPTION The M3004LAB1/M3004LD transmitter IC are designed for infrared remote control systems. It has a total o f 448 commands which are divided into 7 sub-system groups with 64 commands each. The sub-system code may be selected by a press button, a slider switch or hard wired. The M3004LA B1/M3004LD generat e the pattern for driving the output stage. These patterns are pulse distance coded. The pulses are infrared flashes or modulated . The t ransmission mode is defined in conjunction with the sub-system address. Modulated pulses allow receivers with narro w -b a n d p r e a mp l if ie rs f o r im p r o v e d n o is e rejection to be used. Flashed pulses require a wide-band preamplifier within the receiver.
June 1992
VDD DRV 6N DRV 6N DRV 6N DRV 6N DRV 6N DRV 6N DRV 6N OSC OUT OSC IN
3004L-01.EPS
SEN 6N SEN 5N SEN 4N SEN 3N SEN 2N SEN 1N SEN 0N ADRM VSS
18
17 16 15 14
13
12 11
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M3004LAB1 - M3004LD
BLOCK DIAGRAM
DRV OUTPUTS 0N 1N 2N 3N 4N 5N 6N
0N
S 1N E N 2N I 3N N P 4N U T S 5N 6N ADRM KEYBOARD SCAN PULSE DISTANCE MODULATOR REMO OUTPUT
VDD VS S
OSCI
OSCO
INPUTS AND OUTPUTS Ke y m at ri x i nputs a n d outputs (DRV0N to DRV6N and SEN0N to SEN6N) The transmitter keyboard is arranged as a scanned matrix. The matrix consists of 7 driver output s and 7 sense inputs as shown in Figure 1. The driver outputs DRV0N to DRV6N are open drain N-channel tran-sistors and they are conductive in the stand-by mode. The 7 sense inputs (SEN0N to SEN6N) enable the generat ion of 56 command codes. With 2 external diodes all 64 commands are addressable. The sense inputs have P-channel pull-up transistors so that they are HIGH until they are pulled LOW by connecting them to an output via a key depression to initiate a code transmission. ADDRESS MODE INPUT (ADRM) The sub-system address a nd th e transmission mode are defined by connecting the ADRM input to one or more driver outputs (DRV0N to DRV6N) of the key matrix. If more than one driver is connected to ADRM, they must be decouple d by dio d e s . T h i s a l l o w s t h e d e f in i t i o n o f se v e n sub-system addresses as shown in table 3. If driver DRV6N is connected to ADRM, the data output
format of REMO is modulated or if n ot connected, flashed. The ADRM input has switched pull-up and pulldown loads. In the stand-by mode only the pulldown device is active. Whether ADRM is open (sub-system address 0, flashed mode) or connected to the driver output s, this input is LOW and will not cause unwanted dissipation. When the transmitter be comes active by pressing a key, the pull-down device is switched off and the pull-up device is switched on, so that t he applied driver signals are sensed for the decoding of the sub-system address and the mode of transmission. The arrangement of the sub-system address coding is such that on ly the driver DRVnM with the highest number (n) defines the sub-system address, e. g. if drivers DRV2N and DRV4N are conne cted t o ADRM, on ly DRV4N will define the sub-system address. This option can be used in systems requiring more than one sub-system address. The transmitter may be hard-wired for subsystem address 2 by connecting DRV1N to ADRM. If now DRV3N is added to ADRM by a key or a s wit c h , t h e t r a n sm it t e d s u b -s y s t e m a d d re s s changes to 4. A change of the sub-system address will not start a transmission.
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3004L-02.EPS
OSCILLATOR
CONTROL LOGIC
M3004LAB1 - M3004LD
REMOTE CONTROL SIGNAL OUTPUT (REMO) The REMO signal output stage is a push-pull type. In the HIGH state, a bipolar emitter-follower allows a high output current. The timing of the data output format is listed in tables 1 and 2. The information is defined by the distance tb between the leading edges of the flashed pulses or the first edge of the modulated pulses (see Figure 3). The format of the output data is given in Figures 2 and 3 . The data word starts with two toggle bits T1 and T0, followed by three bits for defining the sub-system address S2, S1 and S0, and six bits F, E, D, C, B and A which are defined by the selected key. In the modulated transmission mode the first toggle bit is replaced by a constant reference time bit (REF). This can be used as a reference time for the decoding sequen ce. The toggle bits function is an indication for the decoder that the next instruction has to be considered as a new command. The codes for the sub-system address and the selected key are given in tables 3 and 4. The REMO output is protected against "Lock-up", i.e. the length of an output pulse is limited to < 1ms, even if the oscillator stops during an output pulse. This avoids the rapid discharge of the battery that would otherwise be caused by the continuous activation of the LED. OSCILLATOR INPUT / OUTPUT (OSCI and OSCO) The external component s must be connected to these pins when using an oscillator with a ceramic resonator. The oscillator frequency may vary between 350kHz and 600kHz as defined by the resonator. FUNCTIONAL DESCRIPTION Keyboard operation I n t h e s t and -b y mod e a ll d rive rs (DRV0N to DRV6N) are on (low impedance to VS S). Whenever a key is pressed, one or more of the sense inputs (SENnN) are tied to ground. This will start the power-up sequence. First the oscillator is activated and after the debou nce time tDB (see Figure 4) the output drivers (DRV0N to DRV6N) become active successively. Within the first scan cycle the transmission mode, the applied sub-system address and the selected command code are sensed and loaded into an internal data latch. In contrast to the command code, the sub-system is sensed only within the first scan cycle. If the applied sub-system address is changed while the command key is pressed, the transmitted sub-system address is not altered. In a multiple key stroke sequence (see Figure 5 ) the command code is always altered in accordance with the sensed key. MULTIPLE KEY-STROKE PROTECTION The keyboard is protected against multiple keystrokes. If more than one key is pressed at the same time, the circuit will not generate a new output at REMO (see Figure 5). In case of a multiple key-stroke, the scan repetition rate is increased to detect the release of a key as soon as possible. There are two restrictions caused by the special structure of the keyboard matrix : - The keys switching to ground (code numbers 7, 15, 23, 31, 39, 47, 55 and 63) and the keys connected to SEN5N and SEN6N are not covered completely by the multiple key protection. If one sense input is switched to ground, further keys on the same sense line are ignored, i.e. the command code corresponding to "key to ground" is transmitted. - SEN5N and SEN6N are not protected against multiple keystroke on the same driver line, because this condition has been used for the definition of additional codes (code number 56 to 63). OUTPUT SEQUENCE (data format) The output operation will start when the selected code is found. A burst of pulses, including the latched address and command codes, is generated at the output REMO as long as a key is pressed. The format o f the output pulse train is given in Figures 2 and 3. The operation is terminated by releasing the key or if more than one key is pressed at the same time. Once a sequence is started, the transmitted data words will always be completed after the key is released. The toggle bits T0 and T1 are incremented if the key is released for a minimum time tREL (see Figure 4). The toggle bits remain unchanged within a multiple key-stroke sequence.
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