690

I/O Type Definitions

I/O Type

Definition

I-TTL

Input TTL. Floats High When Left Open.

O-TTL

Output TTL

HS_OUT

High Speed Output. ECL Compatible

HS_IN

High Speed Input, Internally Biased, High Input Resistance

C

External Circuit Node

S

Power Supply or Ground

HDMP-1526 (TRx)

Pin Input Capacitance

Symbol

Parameter

Units

Typ.

Max.

Pin Input Capacitance

pF

1.6

4.0

VCC_TTL

10 k

VBB 1.4 V

10 k

GND_TTL

VCC_TX

or

VCC_RX

ESD

PROTECTION

GND_TTL

VCC_TTL

6 k

36

72

800

O_TTL

I_TTL

GND

ESD

PROTECTION

VCC_TX

HS_OUT

3.2 K

0.01 µF

0.01 µF

Zo = 75

Ω

Zo = 75

Ω

VCC_TXHS

VCC_TXECL

GND

ESD

PROTECTION

-DOUT

+DOUT

270

270

75

75

GND_TXHS

0.01 µF

+DIN

-DIN

ESD

PROTECTION

3.2 K

+

–

+

–

HS_IN

75

75

VCC_RX

GND

GND_RXHS

VCC_RXHS

2 V

2 V

60 µA

60 µA

Figure 10. HS_OUT and HS_IN Simplified Circuit Schematic.

Notes:

1. HS_IN inputs should never be connected to ground as permanent damage to the device may result.

2. 75

Ω serial padding resistors are optional, the serial resistors should be matched to the receiver input bias resistors.

Figure 9. O-TTL and I-TTL Simplified Circuit Schematic.