Zakładka z wyszukiwarką danych komponentów |
|
ISL5586FCM Arkusz danych(PDF) 7 Page - Intersil Corporation |
|
ISL5586FCM Arkusz danych(HTML) 7 Page - Intersil Corporation |
7 / 20 page 4-7 4-WIRE TO 2-WIRE GAIN The 4-wireto 2-wiregain(G42) is defined as the receive gain. It is a function of the terminating impedance, synthesized impedance and protection resistors. The gain is defined from the Receive input terminals (VRXP,VRXM)to the terminating impedance (ZL) on the 2-wire side, and is illustrated in Figure 12. When the device source impedance and the protection resistors equal the terminating impedance, the receive gain equals 2.92dB and is inverted with respect to the input. 2-WIRE TO 4-WIRE GAIN The2-wireto4-wire gain(G24) is the gain from tip and ring to the transmit differential output. The transmit gain is given by Equation 11. Note that VTR is defined on the line side of the protection resistors (reference Figure 13). With ZL set to 600 ohms, the protection resistors set to 50 Ω/terminal and Z0 =ZL-2RP the Transmit gain equals -0.833 (-1.59dB) and is inverted with respect to the 2-wire input (VTR). TRANSHYBRID GAIN The transhybrid gain is defined as the 4-wire to 4-wire gain (G44) and is given by Equation 12 (Reference Figure 14)). Transient Current Limit The drive current capability of the output amplifiers is determined by an externally programmable output current limit circuit which is separate from the DC loop current limit function. The transient current limit is programmed with a resistor to ground at the TL pin. The current limit circuit works in both the source and sink direction, with an internally fixed offset to prevent the current limit functions from turning on simultaneously. The current limit function is provided by sensing line current and reducing the voltage drive to the load when the externally set threshold is exceeded, hence forcing a constant source or sink current. SOURCE CURRENT PROGRAMMING The source current is externally programmed as shown in Equation 13. For example, a source current limit setting of 50mA is programmed with a 35.6k Ω resistor connected from pin 16 of the device to ground. This setting determines the maximum amount of current which flows from Tip to Ring during an off hook event until the DC loop current limit responds. In addition this setting also determines the amount of current which will flow from Tip or Ring when external battery faults occur. SINK CURRENT PROGRAMMING The sink current limit is internally offset 20% higher than the externally programmed source current limit setting. If the source current limit is set to 50mA, the sink current limit will be 60mA. This setting will determine the amount of current which flows into Tip or Ring when external ground faults occur. FUNCTIONAL DESCRIPTION Each amplifier is designed to limit source current and sink current. The diagram below shows the functionality of the circuit for the case of limiting the source current. A similar diagram applies to the sink current limit with current polarity changed accordingly. During normal operation, the error current (IERR) is zero and the output voltage is determined by the signal current (ISIG) multiplied by the 200K feedback resistor. With the current polarity as shown for ISIG, the output voltage moves positive with respect to half battery. Assuming the amplifier output is driving a load at a more negative potential, the amplifier output will source current. During excessive output source current flow, the scaled output current (IO/K) exceeds the reference current (IREF) forcinganerror current (IERR). With the polarity as shown the error current subtracts from the signal current, which reduces the amplifier output voltage. By reducing the output voltage the source current to the load is decreased and the output current is limited. DETERMINING THE PROPER SETTING Since this feature programs the maximum output current of the device, the setting must be high enough to allow for detection of ring trip or programmed off hook loop current, whichever is greater. Z O R1 RP1 – RP2 – () R2 C2 + = (EQ. 9) G 42 2.8 Z L Z O +2RP +ZL ------------------------------------------ – = (EQ. 10) G 24 2 Z O Z O +2RP +ZL ------------------------------------------ – = (EQ. 11) G 44 2.8 Z O Z O 2R P Z L ++ --------------------------------------- – = (EQ. 12) R TL 1780 I SRC ------------- = (EQ. 13) I SN K 1.20 I SRC × = (EQ. 14) FIGURE 2. CURRENT LIMIT FUNCTIONAL DIAGRAM TIP or RING + - IREF =1.21/TL IO IO/K IERR ISIG 20 200K VB/2 ISL5586 |
Podobny numer części - ISL5586FCM |
|
Podobny opis - ISL5586FCM |
|
|
Link URL |
Polityka prywatności |
ALLDATASHEET.PL |
Czy Alldatasheet okazała się pomocna? [ DONATE ] |
O Alldatasheet | Reklama | Kontakt | Polityka prywatności | Linki | Lista producentów 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 |