Download View - Microsemi

Am79R100/101 Vs Am79R79
Device Comparison Brief
This article is a component of the Legerity RSLIC device documentation family; it discusses the
unique features of the Am79R100/101 devices, the similarities between the Am79R100/101
device features and the Am79R79 device features, as well as the differences between each
device.
TABLE OF CONTENTS
Table of Contents............................................................................................................................. 1
What’s new?..................................................................................................................................... 2
Sinusoidal Ringing Waveform .................................................................................................. 2
1. Sinusoidal Ringing Without DC offset .......................................................................... 3
2. Sinusoidal Ringing with DC Offset on the Vring Pin or the Rref Pin ............................ 3
3. Sinusoidal Ringing with DC Offset Between the Rref Pin and the Vring Pin ............... 3
4. Zarlink SLAC™ Device Interface................................................................................... 4
DC Feed ................................................................................................................................... 6
Anti-Saturation Region ............................................................................................................. 6
Ring Trip................................................................................................................................... 8
UL............................................................................................................................................. 8
Protection Circuit...................................................................................................................... 8
Pinout Difference...................................................................................................................... 8
Power Dissipation .................................................................................................................... 9
Pub. # 080458 Rev: C Amendment: /0
Issue Date: June 2001
WHAT’S NEW?
Some applications in Europe require sinusoidal ringing. All the companies in Korea require
sinusoidal ringing of 70-90 volts, regardless of the application. We have found that some phones
will not ring with the Am79R79 device because they require a higher ringing voltage or DC offset
ringing, which are not required in TR57/TR909. In order to address broader markets and meet
these challenging applications, Zarlink has introduced the Am79R100 device and the
Am79R101 device. Each has balanced trapezoidal and sine wave ringing, and provides DC offset
operation at up to a 100 V battery. These new products raise the Zarlink Ringing SLIC device
family to a new level.
The Am79R79 device, which provides balanced trapezoidal ringing, is sufficient for 5 REN in a
short loop (TR909) application. Its 70 Vpk provides 50 Vrms (with a crest factor of 1.25 to a load
of 1400 Ω with 2 x Rf = 100 Ω and Rline = 70 Ω, for a total = 1570 Ω). The Am79R100 device
has a higher ringing voltage. Its 90 Vpk provides 64 Vrms (with a crest factor of 1.25 to a load
of 1400 Ω with 2 x Rf = 100 Ω and Rline = 70 Ω, for a total = 1570 Ω). Note that the Am79R101
device has less driving ability than the Am79R100 device due to its sine wave and 1.4 crest
factor. The unique features of the Am79R100/101 devices will ring those hard-to-ring phones or
push the loop length even further with the same ringer load.
Sinusoidal Ringing Waveform
The sinusoidal ringing waveform generated through the Am79R101 device has an
advantageously low distortion, and satisfies the traditional ringing waveform requirements of
small PBX, WLL, and Pairgain applications. It also has less crosstalk than trapezoidal ringing for
large PBX applications in multi-pair cable transmission. The Am79R101 device also offers offset
ringing, which is created by applying a DC bias voltage on the Rref or Vring pins, and satisfies
most phones that require an offset from ring to tip during the ringing. However, it should be noted
that trapezoidal ringing is usually more than adequate for most applications, and can provide a
good alternative for less power consumption compared to both the sinusoidal and offset ringing
options.
Figure 1
How to Generate DC Offset for Ringing (Vring and Rref Interface)
Ringing
Waveform
0
DC Offset
VBat1
Balanced Sinusoidal Ringing
with Offset
The Am79R100 device is no different than the Am79R79 device in its trapezoidal waveform
generation. Rslew and Cslew can be calculated by using the same formulas given previously
(refer to the Am79R79 device Ringing SLIC Device Technical Review).
For sinusoidal ringing with or without DC offset, there are a variety of ways to apply the ringing
signal to the device. These ways are explained in the following sections.
2
Am79R100/101 Vs Am79R79 Device Comparison Brief
1.
Sinusoidal Ringing Without DC offset
Connect the Rref pin to the digital ground and feed the (desired frequency) sine wave signal to
Vring pin. No AC coupling capacitor is needed, but the amplitude has to be lower than 2 Vpk-pk
to avoid clipping. The sine wave is present at Vab, measured around (Vbat1)/2 V DC.
Figure 2
Balance Ringing Without DC Offset
Am79R101 Device
VRING
RREF
Vring<2Vpk-pk
2.
Sinusoidal Ringing with DC Offset on the Vring Pin or the Rref Pin
Connect the Rref pin to the digital ground and use the voltage divider (shown in Figure 3) to
connect the Vring pin. The bias voltage range at the Vring pin should stay within a maximum of
Vcc/2. A DC blocking cap is needed to prevent upsetting the ring source. There is internal
impedance around 10K in series with the pin, so more voltage tolerance can be expected at Vab.
With a similar approach, the Rref pin can be biased with resistive dividers.
Figure 3
Ringing with DC Offset on Vring Pin
VCC
Am79R101 Device
RR1
VRING
Vring<2Vpk-pk
RR2
3.
RREF
Sinusoidal Ringing with DC Offset Between the Rref Pin and the Vring Pin
Use two resistors to build a voltage divider between the Vcc and DGND. Connect the junction
of the resistors to the Rref pin. The voltage range at the Rref pin should stay within 0 V to
Vcc/2. Apply bias on Vring with higher (or lower) than the DC reference voltage on Rref, and
observe the offset ringing waveform at Vab. If Vring < Vrref, the tip is negatively biased. If Vring
> Vrref, the tip is positively biased. A bigger offset may create clipping on one side of the
ringing waveform if the amplitude is too high. There is a trade off between the amplitude and
the DC offset. When both Rref and Vring are biased, the DC difference between inputs, times
100, is then equal to the offset voltage at Vab (shown in Figure 4).
Am79R100/101 Vs Am79R79 Device Comparison Brief
3
Vout_offset = (Vring – Vrref) x 100
For example, if you need 20 V DC offset at Vab during the ringing, apply 200 mV DC difference
between the Vring and the Rref pins.
Because of the input impedance variation, the resistor value will contribute some tolerance to the
offset output. One should measure the Voffset during ringing to decide upon a set of values.
For the voltage divider bias circuit, a 0.1 uf cap may be needed between the bias point and
ground to reduce the transient effect. Please note that the Rref and Vring inputs should not be
treated as regular op-amp inputs.
Figure 4
Ringing with Bias, Both VRING and RREF Pins
Am79R101 Device
VCC
VRING
Vring < 2 Vpk-pk
RREF
RR1
Vbias
RR2
4.
Zarlink SLAC™ Device Interface
Traditionally the ringing signal is fed into the RSLIC device by separate external devices. Here we
are introducing a ringing source generated from a digital source through the PCM highway, such
as DSP. In order to pass a ringing frequency like 20hz, some filters in the QSLAC™ or ASLAC™
devices need to be adjusted. Within the SLAC™ device, the low-pass filter band limits the signal.
The R digital filters (IIR and FIR), need to be programmed to pass the lower frequency, AISN, and
the Z and B filters need to be turned off to stop the feedback between the Vout and Vin paths.
Gain in the receive path needs to be adjusted to meet the ring output requirement. To minimize
the changes, default settings were used where possible - only two commands need to be
changed: the Command [60/61] Wrd/Rd Operating Function and the Command [82/83] Wrt/Rd
GR filter Coeff. The level of the digital signal can also be adjusted to satisfy the ringing output
requirement.
QSLAC and ASLAC Device Settings for Ring Generation through the PCM Highway:
60 20
82 0111
# Write Operating Functions: choose all the default
settings except for EGR = 1, and for programmed GR
filter = enabled.
# Write GR Filter Coefficients: set Grain = 1.
0E
# Activate
With the above filter settings at 20hz, a –0.4dbm0 sine wave signal on the PCM highway for the
QSLAC device, and a 1.8dbm0 sine wave signal on the PCM highway for the ASLAC device will
4
Am79R100/101 Vs Am79R79 Device Comparison Brief
generate around 1.96Vp-p on the Vout pin. This Vout is enough for the RSLIC device to reach the
required ringing output. The data collected are based on the balance ringing configurations.
Please remember, after generating the ring, the filters need to be reconfigured for normal
transmission setup.
The bias source can also be connected from a Zarlink SLAC device. Normally there is a Vref pin
on the Zarlink QSLAC device (2.1V) or ASLAC device (2.1V) to provide the DC bias for the AC
coupled signal at the SLAC device input and output, but the current driving ability is different
between the SLAC devices. For the QSLAC device, additional circuitry may be needed to
compensate for the driving problem. We use a positive buffer (OP27 from Analog Devices)
connected to Vref output to service 4 channels as reference voltage on the QSLAC device
evaluation board. Any low offset opamp will work depending on how heavy the load (please refer
to the manufacturing data sheet for multi-channel applications, and pay close attention to the
polarity). The ASLAC device has a 1mA driving ability, which should be enough for single channel
applications. (Figures 5 and 6)
Figure 5
DC Offset Ring Interface with the QSLAC™ Device
PCM
Highway
QSLAC
Device
Am79R101 Device
VOUT
VRING
RREF1
5V
OP27
+
VREF
RR1
RREF2
RR2
RREF3
RREF4
Am79R100/101 Vs Am79R79 Device Comparison Brief
5
Figure 6
DC Offset Ring Interface with the ASLAC™ Device
Am79R101 Device
ASLAC
Device
PCM
Highway
VRING
VOUT
RREF
VREF
RR1
RR2
DC Feed
For the majority of short loop applications, the total loop resistance is less than 1 kΩ. The
Am79R100 device increases the DC feed loop resistance with respect to the Am79R79 device Rldc
= 750 Ω (loop plus phone) to Rldc = 1250 Ω (loop plus phone) to deliver the same minimum 20
mA current when Rsgl is connected to ground (Vbat2 = –35 V). The extra 500 Ω loop resistance
is ≅6000 feet longer loop distance (26AWG). The constant current region on the Am79R100/101
devices is the same as the Am79R79 device. The data provided in this section, illustrates the DC
driving capacity. Note that the maximum loop length may create a problem for reliable ring-trip
detection.
Anti-Saturation Region
The Am79R100/101 devices default settings are different from the Am79R79 device. For the
Am79R79 device the Rsgl = open and the Rsgh = open, but for the Am79R100/101 devices,
the Rsgl = open and the Rsgh = ground. The DC feed curves are similar to each other, except that
the Am79R100/101 devices have more headroom. In the OHT mode, the on-hook voltage was
lowered from that of the Am79R79 device. Vab = 49 V to Vab = 45 V. With the Rsgl = ground, the
knee of the low battery anti-sat entry can be raised to 25 V from the nominal 12.5 V with Vbat2 =
−35 V. This increases the utilization of Vbat2, and is beneficial for caller ID applications. With the
appropriate Rsgh connection, the on-hook voltage can be adjusted for MTU and fax machine
application without violating the UL requirement.
The anti-sat calculation formula also changed. The following equations show the Am79R100/101
devices DC feed calculations derived using Mathcad:
6
Am79R100/101 Vs Am79R79 Device Comparison Brief
Am79R100 Device DC Feed Curve with New Formula
Rdc
Rl
100000
600
Vbat1
(Rl = Rl + Rf, Rf = 0)
Rsgl
Vbat2 24
95
Il
0, 0.0001.. 0.06
1000000000
Low bat operation:
2500.
Rl
Rdc
61.44. ( 125000 Rsgl )
Vasl
.
308000 4.92Rsgl
Constant-current
Vab
Vappl
Ilim
Rsgl = open (1G Ω), Vasl = 12.489
Vappl with low battery, Vappl = 16.659
4.17 Vasl
0.025
Vl ( Il )
Constant current
Vappl
4.17.
Il
Ilim
Calculation formula and curve
if( Il > Ilim , Ilim , Vl( Il ) )
Vabl( Il )
Connect the curves
High bat operation:
Rsgh
0
Rsgh = ground default setting
Vash
61.44 .(101000 Rsgh )
Vasl
223000 4. Rsgh
Vash=40.316
Vapph
4.17 Vash
Vh( Il )
Vapph
Vab2( Il )
Vapph = 44.486
4.17.
Il
Ilim
Calculation formula and curve
if( Il > Ilim , Ilim , Vh( Il ) )
Connect the curves
60
50
VAB(Volt)
Vabl
( Il )
40
30
Vab2
( Il )
20
10
0
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
Il(A)
Am79R100/101 Vs Am79R79 Device Comparison Brief
7
Ring Trip
Because a high battery extends the driving ability for both ringing and off hook, we observe that
the loop length of the ring trip for the Am79R100/101 devices are increased compared to the
Am79R79 device. For the Am79R100 device, the recommended setup where Rrt1 = 604K, Rrt2 =
12K, Crt = 1 uf, CF = 1.26, allows Rloop to be extended to a maximum value of 1.1 kΩ with clear
ring trip. For the Am79R101 device, Rrt1 = 700K, Rrt2 = 12K, Crt = 1 uF, CF = 1.41 balance
ringing, the Rloop can reach a maximum of 800 Ω. A small faulty pulse is allowed at the DET
output because most applications will apply debounce capability of typically 13ms, with 20hz
ringing. Debounce circuits will ignore the glitch at the DET output during the transition. There is a
hysteresis applied in both Am79R100/101 devices ring trip circuits to eliminate the threshold
uncertainty. The RC constant for Rrt2 and Crt is measured at less than 30 ms in the worse case
(different phase angle), where it will affect the system level ring-trip requirement and should be
kept as short as possible. If the time constant is too short, the DET will generate a lot of pulses
around the threshold, and the value may need to be adjusted with a particular application.
For DC offset ringing, the ring-trip current is smaller due to the limited swing. With the same value
setup, the ring-trip loop length is expected to be less than the balanced ringing. With 10 V DC
offset applied on the output during ringing, the Am79R101 device can easily ring the Nortel
Venture multi-line feature phone and Casio Phonemate series devices such as the TI-330, 9300.
UL
To meet the fax machine and maintenance termination units (MTU) requirement, the SLIC
device needs to provide a higher on-hook voltage minimum, –43 V. UL has specified that any
DC voltage higher than 60 V is considered hazardous and needs more stringent isolation
requirements. The Am79R100/101 devices apply a diode clamp technique so that the on-hook
high battery should not exceed –54 V in Standby mode.
Protection Circuit
Because the supply voltage has increased from a nominal value of –75 V to –95 V, the protection
circuits we usually use have to move up for higher rating. There are two commonly used devices
for level two protection circuitsthe diode bridge plus the thyristor surge protector and the battery
tracking protection thyristor IC. If we use –70 V for the high battery, the maximum thyristor
breakover voltage must be specified not to exceed –70 V, whereas the minimum must not be less
than the maximum A-to-B line voltage (on hook). Therefore, the current is not sourced from the
SLIC device under the normal line condition. For the battery tracking protection device, which can
be externally programmed by the battery, the minimum breakover is still greater than Vbat, so no
current will be drained during the normal operation. We suggest a Power Innovation
programmable over a voltage protection device, part number TISP61089A (maximum 100 V
limit), which is suitable for Am79R100/101 SLIC device application. Now, there is a TISP61089AS
for small outline SMT that is compliant with UL1950 requirements. The proposed small outline
pinout will be interchangeable with the LCP1521 from ST. The TECCOR BATTRAX P1001SC
protector is another recommended device for this application. In the bridge rectifier and thyristor
device combination application, the fast or ultra fast diodes are strongly recommended for
lightning protection. For details, please refer to the application note, PID# 080270A: Generic SLIC
Device Protection From Lightning Surges and AC Mains Power Cross.
Pinout Difference
Even though the Am79R100/101 devices are pin compatible functional replacements for the
Am79R79 device, there are some differences to note:
8
Pin Function
Am79R79 Device
Am79R100 Device
Am79R101 Device
Pin 7
B2EN
NC
NC
Pin 16
NC
NC
RREF
Am79R100/101 Vs Am79R79 Device Comparison Brief
Unlike the Am79R79 device, the Am79R100/101 devices incorporate B2EN into the state
decoders, which eliminates an I/O control pin with auto battery selection. The following table
illustrates battery selection by each state:
C3 C2 C1
State
E1 = 1
E1 = 0
Battery
0
0
0
Open Circuit
Ring Trip
Ring Trip
Vbat2
0
0
1
Ringing
Ring Trip
Ring Trip
Vbat1
0
1
0
Active
Loop Det.
Ground Key
Vbat2
0
1
1
On Hook TX (OHT) Loop Det.
Ground Key
Vbat1
1
0
0
Tip Open
Loop Det.
Ground Key
Vbat1
1
0
1
Standby
Loop Det.
Ground Key
Vbat1
1
1
0
Active Pol. Rev.
Loop Det.
Ground Key
Vbat2
1
1
1
OHT Pol. Rev.
Loop Det.
Ground Key
Vbat1
Additionally, the Am79R100/101 devices Vbat1 decoupling caps, Cax, Cbx, and Chp voltage
ratings should have enough headroom compared to those of the Am79R79 device.
Power Dissipation
For a condensed linecard design, the power dissipation requirement is even tighter than before.
With a high supply battery, the unit can deliver more power to the load, but you do not want it to
consume more power than it has to. The following table shows the difference in typical power
consumption between devices. Generally speaking, The Am79R100/101 devices consume less
power than the Am79R79 device in Ringing mode.
Table 1
Power Dissipation Between the Am79R79/100/101 Devices, Using 75 V BAT1 and 24 V BAT2
State
Am79R79 Device
Am79R100/101 Devices
Battery
Open Circuit
48 mW
34 mW
Vbat2
Standby
55 mW
43 mW
Vbat1
OHT
200 mW
180 mW
Vbat1
2W
2.6 W
Vbat1
550 mW
540 mW
Vbat2
OHT 300 Ω
Active 300 Ω
Am79R100/101 Vs Am79R79 Device Comparison Brief
9
For more information about all Zarlink products
visit our Web Site at
www.zarlink.com
Information relating to products and services furnished herein by Zarlink Semiconductor Inc. or its subsidiaries (collectively “Zarlink”) is believed to be reliable.
However, Zarlink assumes no liability for errors that may appear in this publication, or for liability otherwise arising from the application or use of any such
information, product or service or for any infringement of patents or other intellectual property rights owned by third parties which may result from such application or
use. Neither the supply of such information or purchase of product or service conveys any license, either express or implied, under patents or other intellectual
property rights owned by Zarlink or licensed from third parties by Zarlink, whatsoever. Purchasers of products are also hereby notified that the use of product in
certain ways or in combination with Zarlink, or non-Zarlink furnished goods or services may infringe patents or other intellectual property rights owned by Zarlink.
This publication is issued to provide information only and (unless agreed by Zarlink in writing) may not be used, applied or reproduced for any purpose nor form part
of any order or contract nor to be regarded as a representation relating to the products or services concerned. The products, their specifications, services and other
information appearing in this publication are subject to change by Zarlink without notice. No warranty or guarantee express or implied is made regarding the
capability, performance or suitability of any product or service. Information concerning possible methods of use is provided as a guide only and does not constitute
any guarantee that such methods of use will be satisfactory in a specific piece of equipment. It is the user’s responsibility to fully determine the performance and
suitability of any equipment using such information and to ensure that any publication or data used is up to date and has not been superseded. Manufacturing does
not necessarily include testing of all functions or parameters. These products are not suitable for use in any medical products whose failure to perform may result in
significant injury or death to the user. All products and materials are sold and services provided subject to Zarlink’s conditions of sale which are available on request.
Purchase of Zarlink’s I2C components conveys a license under the Philips I2C Patent rights to use these components in an I2C System, provided that the system
conforms to the I2C Standard Specification as defined by Philips.
Zarlink, ZL, the Zarlink Semiconductor logo and the Legerity logo and combinations thereof, VoiceEdge, VoicePort, SLAC, ISLIC, ISLAC and VoicePath are
trademarks of Zarlink Semiconductor Inc.
TECHNICAL DOCUMENTATION - NOT FOR RESALE