DS_21x3_001 78Q2123/78Q2133 Data Sheet
Rev. 1.6 31
4.7.4 10BASE-T Transmitter
The Manchester-encoded data pulses, the link pulse and the start-of-idle pulse are tested against the
templates and using the procedures found in Clause 14 of IEEE 802.3.
Parameter Condition Min Nom Max Unit
Peak Differential Output Signal
(see note below)
All data patterns 2.2 2.8 V
Harmonic Content
(dB below fundamental)
Any harmonic
All ones data
Not tested
27 dB
Link Pulse Width 100 ns
Start-of-Idle Pulse Width Last bit 0
Last bit 1
300
350
ns
ns
Note:
Test Condition: Transformer P/N: TLA-6T103
Measured at the line side of the transformer.
Line Termination: 100±1%
4.7.5 10BASE-T Transmitter (Informative)
The specifications in the following table are included for information only. They are mainly a function of
the external transformer and termination resistors used for measurements.
Parameter Condition Min Nom Max Unit
Output return loss 15 dB
Output Impedance Balance 1 MHz < freq < 20 MHz
29 17
10
log
f
dB
Peak Common-
mode Output
Voltage
50 mV
Common-mode rejection 15 V
pk
, 10.1 MHz sine wave
applied to transmitter
common-mode. All data
sequences.
100 mV
Common-mode rejection jitter 15 V
pk
, 10.1 MHz sine wave
applied to transmitter
common-mode. All data
sequences.
1 ns
4.7.6 10BASE-T Receiver
Parameter Condition Min Nom Max Unit
DLL Phase Acquisition Time 10 BT
Jitter Tolerance (pk-pk) 30 ns
Input Squelched Threshold 500 600 700 mVppd
Input Unsquelched Threshold 275 350 425 mVppd
Differential Input Resistance 20
k
Bit Error Ratio
10
-10
Common-mode rejection Square wave
0 < f < 500 kHz
Not tested
25 V
78Q2123/78Q2133 Data Sheet DS_21x3_001
32 Rev. 1.6
Figure 7: Application Diagram for 78Q2123/78Q2133
R18
75
RXD3
C11
0.01UF
R15
49.9
RXD0
R7
100
COL
RXER
R17
75
R13
100
TXD1
R3
680
R11
100
R8
49.9
R2
5.1K
R4
100
U1
78Q2123
16
15
20
19
18
17
12
5
6
7
8
32
23
24
25
28
27
26
2
21
11
1
22
29
14
13
4
3
30
31
10
9
33
TX_EN
TX_CLK
TXD3
TXD2
TXD1
TXD0
RX_CLK
RXD3
RXD2
RXD1
RXD0
INTR
RST
XTLP
XTLN
RXIP
RXIN
VCC
MDC
COL
RX_DV
MDIO
CRS
GND
TX_ER
RX_ER
LED0
LED1
TXOP
TXONGNDD
VCCD
PB_GND
R23
100
J1
RJ45
1
2
3
4
5
6
7
8
910
C5
0.1uF
R22
100
MDC
C13
27pF
R20
75
VCC
TXD3
TXCLK
R9
49.9
C2
0.01uF
C4
0.1uF
R19
75
RXD1
C10
0.1uF
RXCLK
VCC
C1
0.1uF
R5
100
T1
TLA-6T118LF
6
8
7
4
10
9
11
5
15
16
14
12
13
2
3
1
RD+
RD-
RDCT
NC1
RXCT
RX-
RX+
NC2
TXCT
TX+
TX-
NC3
NC4
TDCT
TD-
TD+
TXER
C14
27pF
R6
100
C3
0.01uF
D1
VCC
VCC
MDIO
LED 0
CRS
TXD2
RXD2
C12
0.1UF
R10
100
C13 and C14 must be calibrated
in actual application board for
25.000MHz +/-50ppm.
RXDV
VCC
VCC
D2
TXD0
R12
100
R24
10k
LED 1
Y1
25.000MHz
1.5kV
VCC
R16
75
C15
0.1uF
TXEN
R21
75
R14
49.9
INTR
R1
680
78Q2123
78Q2133
DS_21x3_001 78Q2123/78Q2133 Data Sheet
Rev. 1.6 33
4.8 Isolation Transformers
Two simple 1:1 isolation transformers are required at the line interface. Transformers with integrated
common-mode chokes are recommended for exceeding FCC requirements. This table gives the
recommended line transformer characteristics.
Name Value Condition
Turns Ratio
1 CT : 1 CT ± 5%
Open-Circuit Inductance
350 µH (min)
@ 10 mV, 10 kHz
Leakage Inductance
0.40 µH (max)
@ 1 MHz (min)
Inter-Winding Capacitance 25 pF (max)
D.C. Resistance
0.9 (max)
Insertion Loss 0.4 dB (typ) 0 - 65 MHz
HIPOT 1500 Vrms
Note:
The 100Base-TX amplitude specifications assume a transformer loss of 0.4 dB. For the transmit
line transformer with higher insertion losses, up to 1.2 dB of insertion loss can be compensated by
selecting the appropriate setting in the Transmit Amplitude Selection bits in register MR19.15:14.
4.9 Reference Crystal
If the internal crystal oscillator is to be used, a crystal with the following characteristics should be chosen.
Name Value Units
Frequency 25.00000 MHz
Load Capacitance* 4** pF
Frequency Tolerance
±50
PPM
Aging
±2
PPM/yr
Temperature Stability ( 0 - 70
o
C)
±5
PPM
Oscillation Mode Parallel Resonance, Fundamental Mode
Parameters at 25
o
C ± 2
o
C ; Drive Level = 0.5 mW
Drive Level (typ) 50-100
µW
Shunt Capacitance (max) 10 pF
Motional Capacitance (min) 10 pF
Series Resistance (max) 60
Spurious Response (max) > 5 dB below main within 500 kHz
* Equivalent differential capacitance across the XTLP/XTLN pins.
** If crystal with a larger load is used, external shunt capacitors to ground should be added to make up
the equivalent capacitance difference.

78Q2123S/F

Mfr. #:
Manufacturer:
Maxim Integrated
Description:
Ethernet ICs 10/100 Base Tx Transcvr w/MDIX
Lifecycle:
New from this manufacturer.
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