HDMP-1637A Datasheet, PDF (10/16 Pages) Agilent(Hewlett-Packard) – Gigabit Ethernet SerDes Circuit with Differential PECL Clock Inputs

10
I/O Type Definitions
I/O Type
I-TTL
O-TTL
HS_OUT
HS_IN
C
S
PECL
Definition
Input TTL, Floats High When Left Open
Output TTL
High Speed Output, ECL Compatible
High Speed Input
External Circuit Node
Power Supply or Ground
Positive ECL
HDMP-1637A (TRx) Pin Input Capacitance
Symbol
C_INPUT
Parameter
Input Capacitance on TTL Input Pins
Units
pF
V_CC_TTL
O_TTL
I_TTL
V_CC_TTL
V_CC
Typ.
1.6
Max.
GND_TTL
ESD
PROTECTION
GND
ESD
PROTECTION
GND_TTL
V_BB 1.4 V
Figure 9. O-TTL and I-TTL Simplified Circuit Schematic.
HS_OUT
Zo
Zo
V_CC_TXHS
V_CC_TXECL
V_CC
HS_IN
V_CC
V_CC
+
–
A
+
–
R
R
+DOUT
Zo = 50 Ω _{0.01 µF +DIN}
Zo
R_PAD
150
2*Z0 = 100 Ω
ESD
PROTECTION
-DOUT
GND
150
R_PAD
Zo
Zo = 50 Ω
0.01 µF -DIN
GND
ESD
PROTECTION
GND_TXHS
GND
NOTES:
1. HS_IN INPUTS SHOULD NEVER BE CONNECTED TO GROUND AS PERMANENT DAMAGE TO THE DEVICE MAY RESULT.
2. THE OPTIONAL SERIES PADDING RESISTORS (R_PAD) HELP DAMPEN LOAD REFLECTIONS. TYPICAL R_PAD VALUES FOR
MISMATCHED LOADS RANGE BETWEEN 25-Z0 Ω.
3. FOR PECL REFCLK INPUT PAIR, THE CONSTANT VOLTAGE SUPPLIES (SHOWN AS A) AND RESISTORS R ARE OMITTED.
Figure 10. HS_OUT and HS_IN Simplified Circuit Schematic.