PCD3316
Caller-ID on Call Waiting (CIDCW) receiver
11 March 1999 |
Product specification |
1. General description
The PCD3316 is a low power mixed signal CMOS integrated circuit for receiving physical layer signals like Bellcore’s ‘CPE1 Alerting Signal (CAS)’ and the signals used in similar services. The device is capable of a very high precision detection of the dual tone (2130 and 2750 Hz) by using a patented digital algorithm. The PCD3316 can be used for on-hook and off-hook Caller-ID (CID), Caller-ID on Call Waiting (CIDCW) and Caller-Name (CNAM) applications.
For timing purposes the PCD3316 can be programmed to generate an interrupt signal to the microcontroller every second or every minute. These timings are derived from an on-chip 32.768 kHz oscillator.
Also incorporated in the device are a Frequency Shift Keying (FSK) receiver/demodulator and a ‘Ring or polarity change detector’. The status of the PCD3316, the received FSK data bytes and the ringer period can be read and many options can be selected via the I2C-bus serial interface. Two on-chip oscillators are available. One 3.58 MHz oscillator for all internal functions and a low frequency 32.768 kHz oscillator for the 1 second or 1 minute timing.
In Power-down mode only the polarity comparators and the 32.768 kHz oscillator are active. The CAS detection, the FSK receiver and the 3.58 MHz oscillator can be enabled separately. Detection of a polarity change on the inputs POL0 or POL1, the reception of an FSK data byte, the detection of a CAS tone or a timebase interrupt is signalled to the microcontroller by an interrupt request signal (IRQ). The microcontroller can communicate with the PCD3316 device via the serial interface.
The PCD3316 is designed for use in a microcontroller controlled system. The device is available in a SO16 package.
A demonstration board OM5843 and an application note AN98071 are available.
1. CPE = Customer Premises Equipment.
Philips Semiconductors |
PCD3316 |
|
CIDCW receiver |
2. Features
■Bellcore’s ‘CPE Alerting Signal (CAS)’ and British Telecom’s (BT) ‘Loop State Tone Alert Signal’ detection
■BT’s ‘Idle State Tone Alert Signal’ by means of monitoring the input signal level
■1200 baud FSK demodulator conform Bell 202 and CCITT V23 standards
■Ring or polarity change detector
■Ring period measurement
■Low battery comparator
■Signal level detector
■On-hook and off-hook applications according to Bellcore TR-NWT-000030 and
SR-TSV-002476 specifications
■Receive sensitivity of −37.8 dBm (in 600 Ω) for CAS
■2.5 to 3.6 V supply; low power standby mode
■Selectable 1 second or 1 minute timebase interrupt
■3.58 MHz and 32.768 kHz crystal oscillators
■SO16 package.
3. Applications
■Analog Display Services Interface (ADSI) phones
■Feature phones and adjunct boxes with Bellcore CID, CIDCW and CNAM systems
■Computer Telephony Integrated (CTI) systems.
4.Ordering information
Table 1: Ordering information
Type number |
Package |
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Name |
Description |
Version |
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PCD3316T |
SO16 |
plastic small outline package; 16 leads; body width 7.5 mm |
SOT162-1 |
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9397 750 04824 |
© Philips Electronics N.V. 1999. All rights reserved. |
Product specification |
11 March 1999 |
2 of 30 |
Philips Semiconductors |
PCD3316 |
|
CIDCW receiver |
5. Block diagram
VDD
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16 |
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FSKIN+ |
15 |
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14 |
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FSKIN− |
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PREPROCESSOR |
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CASIN |
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HXIN |
1 |
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3.58 MHz |
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LEVEL |
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2 |
TIMING |
CAS |
FSK |
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HXOUT |
OSCILLATOR |
DETECT |
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3 |
IRQ |
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I2C-BUS |
4 |
SCL |
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POR |
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5 |
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INTERFACE |
SDA |
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LOWBAT |
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POL0 |
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10 |
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PCD3316 |
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POL1 |
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LXIN |
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VOLTAGE |
TIME |
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32.768 kHz |
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REFERENCE |
BASE |
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OSCILLATOR |
7 |
LXOUT |
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8 |
9 |
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MBH983 |
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DGND |
AGND |
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Fig 1. Block diagram.
6.Pinning information
6.1Pinning
handbook, halfpage |
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HXIN |
1 |
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16 |
VDD |
HXOUT |
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FSKIN+ |
2 |
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15 |
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FSKIN− |
IRQ |
3 |
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14 |
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SCL |
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CASIN |
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PCD3316 |
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SDA |
5 |
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12 |
LOWBAT |
LXIN |
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POL0 |
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LXOUT |
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POL1 |
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DGND |
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AGND |
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MBH980 |
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Fig 2. Pin configuration.
9397 750 04824 |
© Philips Electronics N.V. 1999. All rights reserved. |
Product specification |
11 March 1999 |
3 of 30 |
Philips Semiconductors |
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PCD3316 |
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CIDCW receiver |
6.2 Pin description |
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Table 2: |
Pin description |
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Symbol |
Pin |
I/O |
Description |
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HXIN |
1 |
I |
3.58 MHz crystal oscillator input |
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HXOUT |
2 |
O |
3.58 MHz crystal oscillator output |
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IRQ |
3 |
O |
interrupt output; programmable active HIGH or active LOW |
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SCL |
4 |
I |
serial clock line of I2C-bus |
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SDA |
5 |
I/O |
serial data line of I2C-bus |
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LXIN |
6 |
I |
32.768 kHz crystal oscillator input |
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LXOUT |
7 |
O |
32.768 kHz crystal oscillator output |
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DGND |
8 |
− |
digital ground |
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AGND |
9 |
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analog ground |
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POL1 |
10 |
I |
polarity detector input 1 |
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POL0 |
11 |
I |
polarity detector input 0 |
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LOWBAT |
12 |
I |
low battery detector input |
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CASIN |
13 |
I |
input pin for CAS signal |
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FSKIN− |
14 |
I |
negative input for FSK signal |
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FSKIN+ |
15 |
I |
positive input for FSK signal |
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VDD |
16 |
− |
supply |
7.Functional description
7.1Preprocessor and analog inputs
The preprocessor for the CAS detection and the FSK receiver incorporates an
Analog-to-Digital Converter (ADC) and a digital bandpass filter.
The LOWBAT input of the PCD3316 can be used for low battery detection. The voltage on the LOWBAT pin is compared with an internal voltage reference circuit. When the LOWBAT voltage drops below the reference voltage, the Status register, bit 5 is set to logic 1.
The PCD3316 can be forced in a Power-down state by switching off the 3.58 MHz system clock and the ADC. This is done by setting Mode register 2, bit 7 (CIDMD2.7) to logic 0. To guarantee correct operation the following order of actions must be performed (see also Section 7.8 about interrupts):
1.Switch off CAS and FSK detection (if turned on)
2.Read the interrupt register (thus clearing pending interrupts generated by the CAS and FSK detector)
3.Switch off the 3.58 MHz oscillator by clearing bit 7 of Mode register 2.
The two low power comparators (inputs POL0 and POL1) and the 32.768 kHz clock are always active.
9397 750 04824 |
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Product specification |
11 March 1999 |
4 of 30 |
Philips Semiconductors |
PCD3316 |
|
CIDCW receiver |
They can be used for ring or line polarity reversal detection. The POL on/off bit (Mode register 1, bit 4) must be set to enable generation of an interrupt when a polarity change occurs. The result of the two comparators can be read in bits 7 and 6 (POL0 and POL1) of the Status register (see Section 7.4). The 3.58 MHz clock is not needed for the generation of a polarity interrupt.
7.2 CAS detection
After a power-on reset or after enabling the CAS detector the internal registers of the CAS detection function are initialized. The initialization takes a maximum of
100 periods of the 3.58 MHz clock.
If the CAS detection is enabled the PCD3316 will generate an interrupt (Interrupt register, bit 1 is set) when a correct dual tone (2130 and 2750 Hz) is detected. Interrupts will be blocked when the signal level on the CAS input is below the threshold in the level detector.
7.3 FSK reception
The FSK receiver function can be enabled by setting the FSK on/off bit (Mode register 1, bit 7).
In the FSK transmission specification of BT and Bellcore a channel seizure is transmitted first (sequence of 1010..). After the channel seizure a block of marks and finally the data pattern are sent (see Figure 3). These mark bits are detected by the PCD3316 which sets the FSK-BOM Indication bit (Status register, bit 4). The FSK-BOM Indication bit is reset when the FSK receiver is disabled.
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FSK transmission |
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channel seizure |
mark |
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data |
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FSK-BOM
MBH979
Fig 3. FSK transmission specification.
If the FSK-BOM Indication bit is set, the FSK receiver will generate an interrupt after it has received a complete data word. An FSK data word consists of one start bit (space), followed by eight data bits and one stop bit (mark). Interrupts will therefore not be generated during the channel seizure and during the block of marks. When a valid data word has been received, FSK data is available in the FSK data register.
By clearing the FSK-BOM-mask on/off bit (Mode register 1, bit 6), the FSK receiver will not wait with the generation of interrupts until a Begin Of Mark (BOM) has been detected but will handle the channel seizure as normal data. The block of marks which is a string of logic 1 will still not generate interrupts because there are no start bits.
After the generation of an interrupt the IRQ pin will become active (see Figure 4), and the FSK Interrupt bit is set (Interrupt register, bit 5). The received data is available in the FSK data register.
9397 750 04824 |
© Philips Electronics N.V. 1999. All rights reserved. |
Product specification |
11 March 1999 |
5 of 30 |
Philips Semiconductors |
PCD3316 |
|
CIDCW receiver |
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START |
D0 |
D1 |
D2 |
D3 |
D4 |
D5 |
D6 |
D7 |
STOP |
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IRQ
read by serial interface
MBH981
Fig 4. IRQ generation after reading a valid data byte.
The FSK-OVR Error bit (Status register, bit 3) indicates that a previous byte is lost due to an overrun. The FSK-FRM Error bit (Status register, bit 2) indicates an incorrect startor stop-bit. These frame errors indicate that there are synchronization problems. The on-chip level detector can be used to detect a carrier loss during FSK transmission. FSK data can be rejected when the signal level is below the reference level, this to avoid that noise is interpreted as data (Interrupt register, bit 4 is logic 1).
7.4 Ring or polarity change detector
For ring and polarity change detection two comparators are available in the PCD3316. The reference level of the comparators is set internally by the reference voltage generator. The voltage levels on the two polarity comparator inputs, POL0 and POL1, are compared with the reference voltage Vref. If POL0 < Vref or
POL1 > Vref, POL0 and POL1 (Status register, bit 7 and 6) are set respectively and reset if POL0 > Vref and POL1 < Vref. Every time the POL0 status bit changes from logic 1 to logic 0, a POL0 interrupt is generated. Every time the POL1 status bit changes from logic 0 to logic 1, a POL1 interrupt is generated.
The period time of a POL1-POL0-POL1 sequence is available in the Ringer period register. It is preset to 255 on power-on and updated every time a POL1 interrupt is generated. The sequence is:
1.Power-on: Ringer period register = 255
2.First POL1 interrupt: Ringer period register = 255
3.First POL1 interrupt after a POL0 interrupt: Ringer period register = new time
4.First POL1 interrupt after more than 255¤2048 s: Ringer period register = 255.
The period is given in multiples of 1¤2048 s. The maximum value is 255.
The POL1-POL0-POL1 sequence is recognized when one or more POL1 interrupts are generated followed by one or more POL0 interrupts, followed by a POL1 interrupt. The 32.768 kHz clock is needed for the generation of a polarity interrupt.
7.5 Low battery detection
The low battery voltage detection input (pin LOWBAT) is connected to the positive input of a comparator. The negative input is connected to the internal reference voltage. If the voltage on the LOWBAT input pin is less than the reference voltage Vref, the LOW-BAT Indication (Status register, bit 5) is set. If the LOWBAT input rises above Vref again, the LOW-BAT Indication is cleared.
9397 750 04824 |
© Philips Electronics N.V. 1999. All rights reserved. |
Product specification |
11 March 1999 |
6 of 30 |
Philips Semiconductors |
PCD3316 |
|
CIDCW receiver |
The 32.768 kHz clock signal must be available. The LOW-BAT Indication bit does not generate interrupts, thus the bit should be polled.
7.6 Level detect
When the input signal level on the FSK or the CAS input (the one that is selected) is below a threshold of typically −40 dBm, the Low Level Status bit will be set (Interrupt register, bit 4). The level detector can be used to observe a carrier loss during FSK transmission and to detect the ‘Idle State Tone Alert Signal’ for British Telecom. The signal power on the input can be monitored by polling the register bit since it will not generate an interrupt. Signal power is measured in a frequency band corresponding to the selected operation mode, FSK (1000 to 2200 Hz) or CAS (2000 to 2800 Hz).
The Low Level Status bit will be updated every 8 ms. When FSK and CAS are both disabled the signal level on the FSK input is measured. The 32.768 kHz clock signal must be available.
7.7 Time base
The 32.768 kHz oscillator is used to generate either a 1 second or a 1 minute interrupt signal. If the TB on/off bit is set (Mode register 2, bit 6) every second or minute an interrupt is generated and MIN Interrupt and/or SEC Interrupt bits (Interrupt register, bit 7 and 6) are set. After reading the Interrupt register the interrupt is cleared.
The SEC/MIN (Mode register 2, bit 5) selects whether every second (SEC/MIN is set) or every minute (SEC/MIN is cleared) an interrupt is generated. All possible selections are shown in Table 3. Resetting bit TB on/off in Mode register 2 (bit 6) will only disable time base interrupts, and the 32.768 kHz oscillator will continue to run.
7.8 Interrupt
The interrupt request output (IRQ) is active HIGH by default. The polarity of the IRQ output can be made active LOW by the INT Polarity HIGH/LOW bit (Mode register 1, bit 3). The IRQ pin is in 3-state when not active, so an external pull-up or pull-down resistor is required. The interrupt cause is indicated by the flags in the Interrupt register. Interrupt flags are set by hardware but must be reset by software. All flags of the Interrupt register are reset when the register is read via I2C-bus interface.
The IRQ pin is deactivated at the positive edge of SCL which reads the first data bit of the Interrupt register. The IRQ pin will stay inactive for one SCL cycle. IRQ can handle a next interrupt after the next positive edge of SCL.
Table 3: Selection of interrupt modes
Mode register 2 (CIDMD2) |
Interrupt register (CIDINT) |
Interrupt |
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TB on/off |
SEC/MIN |
MIN Interrupt |
SEC Interrupt |
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(CIDMD2.6) |
(CIDMD2.5) |
(CIDINT.7) |
(CIDINT.6) |
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0 |
X [1] |
0 |
0 |
no time base interrupt (time base is reset) |
1 |
0 |
1 |
0 |
every minute an interrupt is generated; no second interrupt |
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1 |
1 |
1 |
1 |
every second an interrupt is generated; every minute an |
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interrupt is generated |
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[1]X = don’t care.
9397 750 04824 |
© Philips Electronics N.V. 1999. All rights reserved. |
Product specification |
11 March 1999 |
7 of 30 |
Philips Semiconductors |
PCD3316 |
|
CIDCW receiver |
7.9 The internal Power-on reset (POR)
The device contains an on-chip Power-on reset circuitry which activates a reset as
long as VDD is below a predefined level VPOR(H). If VDD exceeds VPOR(H), the
3.58 MHz oscillator will start. The PCD3316 is initialized and the internal registers are set to the default value (see Section 7.13). It takes a maximum of 100 cycles of the 3.58 MHz clock to initialize all internal functions. The POR circuitry also ensures, that the chip will be switched off as soon as a falling VDD reaches a predefined level
(VPOR(L)).
7.10 3.58 MHz oscillator circuitry
The 3.58 MHz oscillator is needed for the FSK receiver and the CAS detection. This on-chip Amplitude Controlled Oscillator (ACO) circuitry is a single-stage inverting amplifier biased by an internal feedback resistor Rfb. The oscillator circuit is shown in Figure 5. When using a quartz resonator to drive the oscillator, normally no external components are needed.
When using ceramic resonators to drive the oscillator, in some cases external components are needed; refer to the ceramic resonator product specifications. Two different configurations are shown in Figure 6a and Figure 6b.
handbook, halfpage
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AMPLITUDE |
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C1i |
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MGK723 |
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Fig 5. Oscillator.
To drive the device with an external clock source, apply the external clock signal to HXIN, and leave HXOUT to float, as shown in Figure 6c. If the amplitude of the input signal is less than VDD to DGND or a sine wave is applied, capacitive decoupling is needed as shown in Figure 6d.
In the Power-down mode (Mode register 2, bit 7 = 0), the oscillator is stopped and HXIN and HXOUT are internally pulled LOW. The current of the whole oscillator is switched off.
9397 750 04824 |
© Philips Electronics N.V. 1999. All rights reserved. |
Product specification |
11 March 1999 |
8 of 30 |
Philips Semiconductors |
PCD3316 |
|
CIDCW receiver |
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handbook, halfpage |
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PCD3316 |
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PCD3316 |
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handbook, halfpage |
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a. |
Standard oscillator: quartz or PXE. |
b. Oscillator: quartz or PXE with external capacitors. |
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handbook, halfpage |
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PCD3316 |
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3.58 MHz |
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3.58 MHz |
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square wave |
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sine wave |
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MGK728 |
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c. |
External clock: square wave. |
d. External clock: sine wave. |
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Fig 6. 3.58 MHz oscillator configurations.
MBK948
500 handbook, halfpage
R1 (Ω)
400
300
(1) |
(2) |
(3) |
200
100
0
0 |
20 |
40 |
60 C0 (pF) 80 |
C1e and C2e are the external load capacitances (see Figure 6b). Normally, they are not needed due to integrated load capacitances of 10 pF; see curve (2).
(1)C1e = C2e = 22 pF.
(2)C1e = C2e = 0 pF.
(3)C1e = C2e = 12 pF.
a. Resonator requirements for the ACO.
handbook, halfpage |
C1 L1 |
R1 |
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R0
MBK947
C0
For correct function of the oscillator, the values of R1 and C0 of the chosen resonator (quartz or PXE) must be below the related curve lines shown in Figure 7a. The value of the parallel resistor R0 must be less than 47 kΩ.
The wiring between chip and resonator should be kept as short as possible.
b.Resonator equivalent circuit.
Fig 7. Resonator requirements and equivalent circuit.
9397 750 04824 |
© Philips Electronics N.V. 1999. All rights reserved. |
Product specification |
11 March 1999 |
9 of 30 |
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