Features Low Power Consumption Very High Sensitivity (. µv) High Selectivity by Using Crystal Filter Power-down Mode Available Only Few External Components Necessary Complementary Output Stages AGC Hold Mode Wide Frequency Range ( khz to khz) Low Battery Voltage Applications (. V to 3.6 V) Description The T7 is a bipolar integrated straightforward-receiver receiver circuit in the frequency range of khz to khz and is suitable for all kinds of transmitters. The device is designed for radio-controlled clock applications with very high sensitivity and low power consumption. Time-code Receiver T7 Figure. Block Diagram RFO RFI DEM IN OUT IN AGC PEAK DET. OUT BIAS PK HLD Rev. 57A RCCIC /3
PAD Coordinates The T7 is available as die for chip-on-board mounting and in a SSO6 package. DIE Size:.65. mm PAD Size: µm (contact window µm) Thickness: 3 µm ± µm Table. Pad Coordinates Symbol Function x-axis (µm) y-axis (µm) Pad # (Die) Pin # (SSO6) () RFI RF-input (from crystal) 3 Ground 3 93 3 RFO RF-output (to crystal) 3 77 3 Vcc Supply voltage 3 5 5 IN Antenna input 3 33 5 6 IN Antenna input 3 6 6 7 OUT Active high output 3 6 7 OUT Active low output 3 33 Power on intput active low 3 5 9 PK Peak detector output 3 77 3 HLD AGC hold active low 3 93 DEM Demodulator output 3 5 Note:. Pins, 7, and 6 are not connected. Figure. PAD Layout Y RFI HKW UE65 DEM The PAD co-ordinates are referred to the left bottom point of the contact window. HLD RFO 3 PK 9 IN 5 OUT IN 6 7 OUT Reference Point (%) X T7 57A RCCIC /3
T7 Pin Configuration Figure 3. Pinning SSO6 n.c. 6 n.c. RFI 5 DEM 3 HLD RFO 3 PK 5 T7 IN 6 OUT IN 7 OUT n.c. 9 n.c. Absolute Maximum Ratings Parameters Symbol Value Unit Supply voltage V CC 5.5 V Ambient temperature range T amb - to +5 C Storage temperature range R Stg -55 to +5 C Junction temperature T j 5 C Electrostatic handling (MIL Standard 3 D HBM) ±V ESD V 57A RCCIC /3 3
Electrical Characteristics V CC = 3 V, reference point Pin 3, input signal frequency 77.5 khz ± 5 Hz; carrier voltage %, reduction to 5% for t MOD = ms; T amb = 5 C, unless otherwise specified Parameters Test Conditions Symbol Min. Typ. Max. Unit Supply voltage range Pad/Pin V CC V CC. 5.5 V Supply current Pad/Pin V CC I CC 5 µa Set-up time after V CC ON V CC = 3 V t.5 s Reception frequency range f in khz Minimum input voltage Pad/Pin IN, IN V in..6 µv Maximum input voltage Pad/Pin IN, IN V in 3 5 mv Input amplifier maimum. gain (V PK =.V) V U 53 db Input amplifier minimum gain (V PK =.V) V U - db Output voltage (OUT, low) external circuitry like NPN open collector stage Output voltage (OUT, high) external circuitry like PNP open collector stage Output current (OUT high) external circuitry like NPN open collector stage Output current (OUT low) external circuitry like NPN open collector stage Output current (OU high) external circuitry like PNP open collector stage Output current (OUT low) external circuitry like NPN open collector stage V l = µv; I OUT L = 3 µa V l = µv; I OUT H = 3 µa V l = µv; % amplitude V l = µv; 5% amplitude V l = µv; 5% amplitude V l = µv; % amplitude V Out L.3 V V Out H V DD -.5 V DD -.3 V I OUT H µa I OUT L 3 5 µa -I OUT H 3 5 µa -I OUT L µa Power-down Control; Pad/Pin Switch current receiver ON V = V, Pad -I µa Quiescent current receiver OFF V = V CC, Pad/Pin V CC I CC.5 µa Set-up time after t.5 s AGC Hold Mode; HLD Pad/Pin HLD Switch voltage receiver normal mode V HLD = V CC -IHLD V CC -. V Input current AGC in hold mode V HLD = V µa AC Characteristics Output pulse width for OUT and OUT Output pulse width for OUT and OUT Modulation according DCF77, ms pulse Modulation according DCF77, ms pulse t WO 7 95 3 ms t WO 7 95 3 ms T7 57A RCCIC /3
T7 Figure. Test and Application Circuitry with Pull-up Resistor (77.5 khz) 775 Hz active low Vcc ~ 5E k IN IN C DEM see Table (P. ) 7nF RFO RFI DEM OUT k Signal out active low AGC PEAK DET. OUT BIAS PK HLD Receiver ON 3 Volt C PK see Table (P. ) µf off AGC HOLD on Figure 5. Test and Application Circuitry with Pull-down Resistor (77.5 khz) 775 Hz active low Vcc IN C DEM see Table (P.) 7nF RFO RFI DEM OUT ~ 5E k IN active high AGC PEAK DET. OUT Signal out BIAS PK HLD k Receiver ON 3 Volt C PK see Table (P.) µf off AGC HOLD on 57A RCCIC /3 5
IN, IN A Ferrite antenna is connected between IN and IN. For high sensitivity, the Q factor of the antenna circuit should be as high as possible. Please note that a high Q factor requires temperature compensation of the resonant frequency in most cases. We recommend a Q factor between and 5. An optimal signal-to-noise ratio will be achieved by a resonant resistance of k to k. Figure 6. IN, IN, PAD (Pin 5) k k RF-Amp IN PAD 6 (Pin 7) IN PAD 5 (Pin 6) from AGC PAD (Pin 3) RFO In order to achieve a high selectivity, a crystal is connected between the RFO and RFI Pins. It is used with the serial resonant frequency of the selected reception frequency (e.g., 6 khz WWVB, 77.5 khz DCF or khz JJY) and acts as a serial resonator. The equivalent parallel capacitor of the filter crystal is internally compensated so that the bandwidth of the filter is about Hz. The impedance of RFI is high. Parasitic loads have to be prevented. Figure 7. RFO PAD (Pin 5) RFO 55k PAD 3 (Pin ) PAD (Pin 3) 6 T7 57A RCCIC /3
T7 RFI Figure. RFI PAD (Pin 5) 5k RFI 5k PAD (Pin ) PAD (Pin 3) Demolutator (DEM) To ensure this function, an external capacitor has to be connected at this output. The value of the capacitor needs to be adapted to the frequency of the received signal. Frequencies below 7 khz require a value of 6 nf to nf; whereas, frequencies of 7 khz and more can work with 7 nf to 6 nf. Figure 9. DEM PAD (Pin 5) DEM 5k PAD (Pin5) PAD (Pin 3) 57A RCCIC /3 7
HLD AGC Hold Mode: HLD high (V SL = V CC ) sets normal function, SL low (V SL = ) holds for a short time the AGC voltage. For example, this can be used to prevent the AGC from peak voltages created by a stepper motor. Figure. HLD PAD (Pin 5) HLD PAD (Pin ) PAD (Pin 3) PK An external capacitor has to be connected to ensure the function of the peak detector. The value of the capacitance influences the AGC regulation time. Figure. PK PAD (Pin 5) PK PAD (Pin 3) from Demodulator PAD (Pin 3), and serve as supply voltage input. To power-down the circuitry, it is recommended to use the input instead of switching the power supply as the latter results in an extended power-up time. T7 57A RCCIC /3
T7 If is connected to, the receiver will be activated. The set-up time is typically.5 s after applying at this pin. If is connected to V CC, the receiver will switch to power-down mode. Figure. PAD (Pin 5) PAD 9 (Pin ) BIAS Generator PAD (Pin 3) OUT, OUT The serial signal of the time-code transmitter can be directly decoded by a microcomputer. Details about the time-code format of several transmitters are described separately. The output consists of a combination of a NPN/PNP open-collector stage. The function depends on the external circuitry: A load resistor is connected from OUT to V CC, OUT is connected to. This performs the functionality of a NPN open-collector stage. In this case, the signal is active low. A load resistor is connected from OUT to, OUT is connected to V CC. This performs the functionality of a PNP open-collector stage. In this case, the signal is active high. Figure 3. OUT, OUT OUT PAD (Pin) from Comparator OUT PAD 7 (Pin) 57A RCCIC /3 9
Design Hints for the Ferrite Bar Antenna The bar antenna is a critical device of the complete clock receiver. Observing some basic RF design rules helps to avoid possible problems. The IC requires a resonant resistance of k to k. This can be achieved by a variation of the L/C-relation in the antenna circuit. It is not easy to measure such resistances in the RF region. A more convenient way is to distinguish between the different bandwidths of the antenna circuit and to calculate the resonant resistance afterwards. Thus, the first step in designing the antenna circuit is to measure the bandwidth. Figure shows an example for the test circuit. The RF signal is coupled into the bar antenna by inductive means, e.g., a wire loop. It can be measured by a simple oscilloscope using the : probe. The input capacitance of the probe, typically about pf, should be taken into consideration. By varying the frequency of the signal generator, the resonant frequency can be determined. Figure. Antenna Tuning Set-up RF signal generator 77.5 khz Scope Probe : w MW wire loop C res At the point where the voltage of the RF signal at the probe drops by 3 db, the two frequencies can then be measured. The difference between these two frequencies is called the bandwidth (BW A ) of the antenna circuit. As the value of the capacitor C res in the antenna circuit is known, it is easy to compute the resonant resistance according to the following formula: R res = ------------------------------------------------- BW A C res where, R res is the resonant resistance, BW A is the measured bandwidth (in Hz) C res is the value of the capacitor in the antenna circuit (in Farad). If high inductance values and low capacitor values are used, the additional parasitic capacitance of the coil (V pf) must be considered. The Q value of the capacitor should be no problem if a high Q type is used. The Q value of the coil differs more or less from the DC resistance of the wire. Skin effects can be observed but do not dominate. Therefore, it should not be a problem to achieve the recommended values of the resonant resistance. The use of thicker wire increases the Q value and accordingly reduces bandwidth. This is advantageous in order to improve reception in noisy areas. But, temperature compensation of the resonant frequency might become a problem if the bandwidth of the antenna circuit is low compared to the temperature variation of the resonant frequency. The Q value can also be reduced by a parallel resistor. T7 57A RCCIC /3
T7 Temperature compensation of the resonant frequency is a must if the clock is used at different temperatures. Please ask your supplier of bar antenna material and capacitors for specified values of the temperature coefficient. Furthermore, some critical parasitics have to be considered. These are shortened loops (e.g., in the ground line of the PCB board) close to the antenna and undesired loops in the antenna circuit. Shortened loops decrease the Q value of the circuit. They have the same effect like conducting plates close to the antenna. To avoid undesired loops in the antenna circuit, it is recommended to mount the capacitor C res as close as possible to the antenna coil or to use a twisted wire for the antenna-coil connection. This twisted line is also necessary to reduce feedback of noise from the microprocessor to the IC input. Long connection lines must be shielded. A final adjustment of the time-code receiver can be carried out by pushing the coil along the bar antenna. Application Hints For the maximum performance at different frequencies, please use the values given in Table. Table. Capacitor Values for Different Frequencies Reception Frequency (Hz) Data Protocol of Transmitter Crystal Frequency (Hz) C DEM (µf) C PU (µf), JJY,.7 6, JJY, WWVB 6,.7 6, MSF 6,.7 75, DCF 77,5 7. 57A RCCIC /3
R A Z Z A P P3 German Transmitter Station: DCF 77 Frequency: 77.5 khz Transmitting Power: 5 kw Location: Mainflingen/Germany Geographical Co-ordinates: 5.'N, 9 'E Time of Transmission: Permanent Figure 5. Protocol German Transmitter Time frame minute ( index count second ) Time frame 5 5 5 3 35 5 5 55 5 S P coding when required minutes hours calendar day month day of the week year Example:9.35 h s P P seconds 3 5 6 7 9 3 3 3 33 3 35 minutes hours Start Bit Parity Bit P Parity Bit P Modulation Time-code Format The carrier amplitude is reduced to 5% at the beginning of each second for a period of ms (binary zero) or ms (binary one), except the 59th second. The time-code format consists of -minute time frames. There is no modulation at the beginning of the 59th second to indicate the switch over to the next -minute time frame. A time frame contains BCD-coded information of minutes, hours, calendar day, day of the week, month and year between the th second and 5th second of the time frame, including the start bit S ( ms) and parity bits P, P and P3. Furthermore, there are 5 additional bits R (transmission by reserve antenna), A (announcement of change-over to summer time), Z (during summer time ms, otherwise ms), Z (during standard time ms, otherwise ms) and A (announcement of leap second) transmitted between the 5th second and 9th second of the time frame. Note: This is based on information of Deutsche Bundespost. T7 57A RCCIC /3
T7 British Transmitter Station: MSF Frequency: 6 khz Transmitting Power: 5 kw Location: Teddington, Middlesex Geographical Co-ordinates: 5 'N, 'W Time of Transmission: permanent, except the first Tuesday of each month from. h to. h. Figure 6. Protocol British Transmitter Time frame minute ( index count second) Time frame 5 5 5 3 35 5 5 55 5 Switch over to the next time frame year month day of month day of week hour minute minute identifier Parity BST check bits hour + minute day of week day + month year BST 7 GMT change impending 5 ms 5 ms Example: March 993 Modulation seconds 7 9 3 5 6 7 9 3 year month The carrier amplitude is switched off at the beginning of each second for a period of ms (binary zero) or ms (binary one). Time-code Format The time-code format consists of -minute time frames. A time frame contains BCDcoded information of year, month, calendar day, day of the week, hours and minutes. At the switch-over to the next time frame, the carrier amplitude is switched off for a period of 5 ms. The prescence of the fast code during the first 5 ms at the beginning of the minute in not guaranteed. The transmission rate is bits/s and the code contains information of hour, minute, day and month. 57A RCCIC /3 3
P FRM P P ADD SUB ADD P P US Transmitter Station: WWVB Frequency: 6 khz Transmitting Power: 5 kw Location: Fort Collins Geographical Co-ordinates: 'N, 5 3'W Time of Transmission: Permanent Figure 7. Protocol US Transmitter Time frame minute Time frame ( index count second) 5 5 5 3 35 5 5 55 5 P3 P5 minutes hours days UTI sign UTI correction year daylight savings time bits leap second warning bit leap year indicator bit " = non leap year " = leap year Example: UTC. h Time frame P P P seconds 3 5 6 7 9 3 5 6 7 9 minutes Frame-reference marker hours Modulation Time-code Format The carrier amplitude is reduced by db at the beginning of each second and is restored within 5 ms (binary one) or within ms (binary zero). The time-code format consists of -minute time frames. A time frame contains BCDcoded information of minutes, hours, days and year. In addition, there are 6 positionidentifier markers (P thru P5) and frame-reference marker with reduced carrier amplitude of ms duration. T7 57A RCCIC /3
PO FRM P P P3 PA PA SU P SU P5 LS LS P T7 Japanese Transmitter Station: JJY Frequency: khz and 6 khz Transmitting Power: 5 kw Location: Sanwa, Ibaraki Geographical Co-ordinates: 36 ' N, 39 5' E Time of Transmission: Permanent Figure. Protocol Japanese Transmitter Time frame minute (index count second) Time frame 5 5 5 3 35 5 5 55 5 minutes hour s days Example:. h Time frame P P year weeks leap second P seconds 59 3 5 6 7 9 3 5 6 7 9 minutes hours Frame-reference marker (FRM) Position-identifier marker P Position identifier marker P. s. s.5 s "" "" "P".5 second: Binary one. second: Binary zero. second: Identifier markers P...P5 Modulation Time-code Format The carrier amplitude is % at the beginning of each second and is switched off after 5 ms (binary one) or after ms (binary zero). The time-code format consists of -minute time frames. A time frame contains BCDcoded information of minutes, hours and days. In addition, there are 6 position-identifier markers (P thru P5) and frame-reference marker (FRM) with reduced carrier amplitude of 5 ms duration. 57A RCCIC /3 5
Ordering Information Extended Type Number Package Remarks T7-DDT No Die in trace T7-FB SSO6 T7-FBG3 SSO6 Taped and reeled T7-DBQ No CSP Chip Scale Package Package Information 6 T7 57A RCCIC /3
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