input Data Format: Serial, asynchronous, standard TTL levels
Modulation Technique:
Binary, phase-coherent Frequency Shift Keying (FSK) TC Output Level: —3dBm into 6000
“requency Accuracy:
~ +0.4Hz all modems except Bell 202 (mark)
+1.0Hz Bell 202 (mark)
Harmonics: ~ 45dB from fundamental for single tones
Detay uncertainty for TD logic input change to TC frequency change: <8.3us
Out-of-band energy: See Figure 16 RECEIVER
Output Data Format: Serial, asynchronous, TTL levels Demodulation Technique: Differential FM Detection Sensitivity at Receiver Input: OdBm to — 48dBm Frequency Deviation Tolerance: + 16Hz Carrier Detect Threshold:
ON >-43dBm + 1dB OFF <-48dBm + 1dB TEST MEASUREMENT SETUP
Am7910 pertormance is characterized using the test equipment setup shown in Figure 17. The HP1645A data error analyzer is used to generate 511-bit pseudo random binary sequences (PRBS) at Dour for testing the modem. The 1645A also re-
ceives and analyzes the 511-bit digital pattem at Diy after it
has progressed around the test loop. A reference transmitterconverts the digital sequence generated by the HP1645A into an FSK signal. The FSK signal is typically adjusted to different
levels from -— 12 to —45dBm. The level-adjusted FSK signal or
incident signal then passes through three pieces of equipment which comprise the telephone line simulator. The Wandel and Golterman TLN-1 and DL2Z-4 simulate amplitude and group delay characteristics typical of a wide variety of phone lines.Line perturbations, such as amplitude hits and phase hits, may
be injected by the Bradley 2A/2B.
The summing amplifier which drives the modem under test has three inputs. One of these inputs is the incident FSK signal which has been passed through a simulated phone fine. The second input is from an optionally filtered noise source in order to simulate noise conditions which may be encountered on phone lines. The third input is from the transmitter of the Am7910 under test. This third input simulates the adjacent channel signal seen at the input of the Am7910 receiver due to the duplexer used on 2-wire lines. If 4-wire testing is being performed, the adjacent channel would not normally be included.
The HP3551A of HP3552A Transmission Test Set is used tor measuring various levels which the modem under test is to re- ceive. The levels of each of the three inputs to the summing amplifier should be measured independently of the other two inputs. For instance, the incident signal level should be mea- sured by the transmission test set with no adjacent channel or noise present. The dashed line from the noise generator shows that the noise may or may not be measured at the output of the noise generator, depending on whether or not an optional filter is used, or on the characteristics of the filter.
Figure 16. Out-of-Band Transmitter Energy
Figure 17. BER and Distortion Measurement Test Setup
eas.
MAXIMUM RATINGS
Storage Temperature -65 to +125°C
Ambient Temperature under Bias 0 to +70°C
Voc with Respect to VoGnp +6V/-.4V
Ves with Respect to VoGno -6V/+.4V
a 2gnal Voltages with Respect to VpGnp +5V
The products described by this specification include intemal circuitry designed to protect input devices from damaging accumulations of charge. It is suggested, nevertheless, that conventional precautions be observed during storage, handling and use in order to avoid exposure to excessive voltages.
Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device retiability.
OPERATING RANGE
Ambient Temperature Vec Ves “acne Voc
OC x Ta < +70°C +5.0V 25% | —5.0V +5% cs
DC CHARACTERISTICS
Digital Inputs: TD, RTS, TS, MCp~MCq, OTR, DIR, RING, BTD, BATS Outputs: RD, CTS, CD, BRD, BCTS, BCD
Parameters Description Test Conditions Min Typ Max Unit
Output LOW Voltage
St Extemal Clock Input HIGH (XTAL,)
Vic
Extemal Clock input LOW (X TAL)Extemal Reset input HIGH (RESET) External Reset Input LOW (RESET)
Digital Input Leakage Current Voc Suppty Current Vee Suppty Current
iu
~1.6V < Vag < +1.6V
REF Vacnp Analog Output (TC):
Vic Output Voltage AR, = 6002 +t Volts
Vicos Output DC Offset +200 mV
STANDARD LOAD CIACUIT
APPLICATIONS
Figure 24 depicts a stand-alone Am7910 configuration. An op amp and three resistors provide a duplexor function to put the transmitter output onto the line while receiving adjacent chan- nel data from the line. Connection to the line is via a Data Ac- cess Arrangement (DAA). Note the lack of extemal analog fil- ters. The TTL handshake signals may be level converted to RS-232, RS-422, or V.24 using appropriate devices. Mode control lines are hardwired or connected to switches.
Figure 24. Stand-Alone Am7910 Application
Sr
L\
OLB « ONGITAL LOOPBACK
re] ALB + ANALOG LOOPBACK LOCAL COPY
*See Figure 13
Notes: 1. Cy = 50pF including stray and wiring capacitance 2. All diodes are IN3064 or equivalent
3. All resistors are 1/8 watt 4. Voc = S volts +1%
Figure 25 depicts use of the Am7910 when a microprocessor resides in the same physical location. The duplexor/line interface is identical to the above configuration. However, the handshake signals interface directly to a UART-type device which in turn interfaces to a microprocessor. The mode control lines might also be controtled by the microprocessor.
Ped +s v
aps eat
MN
Am7910PC Am7910LC Oe tTy< +70°C
ORDERING INFORMATION
Temperature