Electronic Components Datasheet Search |
|
ILA1068 Datasheet(PDF) 3 Page - List of Unclassifed Manufacturers |
|
ILA1068 Datasheet(HTML) 3 Page - List of Unclassifed Manufacturers |
3 / 11 page ILA1068 3 FUNCTIONAL DESCRIPTION Supplies VCC, LN, SLPE, REG and STAB Power for the IC and its peripheral circuits is usually obtained from the telephone line. The ILA1068 develops its own supply at VCC and regulates its voltage drop. The supply voltage VCC may also be used to supply external circuits, e.g. dialling and control circuits. Decoupling of the supply voltage is performed by a capacitor between VCC and VEE; the internal voltage regulator is decoupled by a capacitor between REG and VEE. The DC current flowing into the set is determined by the exchange voltage (Vexch), the feeding bridge resistance, (Rexch) and the DC resistance of the telephone line (Rline). An internal current stabilizer is set by a resistor of 3.6 K Ω between the current stabilizer pin STAB and VEE (see Fig.1). Figure 1. Supply arrangement If the line current Iline exceeds the current ICC + 0.5 mA required by the circuit itself (approximately 1mA) plus the current Ip required by the peripheral circuits connected to VCC, then the voltage regulator diverts the excess current via LN. The regulated voltage on the line terminal (VLN) can be calculated as: VLN = Vref + ISLPE x R9 VLN = Vref + ((Iline - ICC - 0.5 x 10 3)-I p) x R9, where Vref is an internally generated temperature compensated reference voltage of 4.2 V and R9 is an external resistor connected between SLPE and VEE. The preferred value for R9 is 20 Ω. Changing the value of R9 will also affect microphone gain, DTMF gain, gain control characteristics, side-tone level, the maximum output swing on LN and the DC characteristics (especially at lower voltages). Under normal conditions, when ISLPE >> ICC + 0.5 mA + Ip , the static behaviour of the circuit is that of a 4.2 V regulator diode with an internal resistance equal to that of R9. In the audio frequency range, the dynamic impedance is largely determined by R1 (see Fig.2). The internal reference voltage can be adjusted by means of an external resistor (RVA). This resistor, connected between LN and REG, will decrease the internal reference voltage; when connected between REG and SLPE, it will increase the internal reference voltage. Current (Ip) available from VCC for supplying peripheral circuits depends on external components and on the line current. Leq = C3 x R9 x RP RP = 17.5K Ω Figure 2. Equivalent impedance circuit Microphone inputs MIC+ and MIC- and gain pins GAS1 and GAS2 The circuit has symmetrical microphone inputs. Its input impedance is 64 K Ω (2 x32 KΩ) and its voltage gain is typically 52 dB (when R7 = 68 K Ω, see Figure 5). Dynamic, magnetic, piezo-electric or electret (with built-in FET source followers) can be used. The gain of the microphone amplifier can be adjusted between 44 dB and 60 dB. The gain is proportional to the value of R7 connected between GAS1 and GAS2. An external capacitor C6 of 100 pF between GAS1 and SLPE is required to ensure stability. A larger value may be chosen to obtain a firs t-order low-pass filter. The cut-off frequency corresponds to the time constant R7 x C6. VCC V EE ICC I SLPE I SLPE I C I line R line R exch V exch LN 0.5 mA +0.5 mA R1 R9 STAB SLPE REG C3 R5 C1 + + + - - - peripheral circuit DC AC IlA1068 |
Similar Part No. - ILA1068 |
|
Similar Description - ILA1068 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |