720

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

C

External Circuit Node

S

Power Supply or Ground

HDMP-1636/46 (TRx)

Pin Input Capacitance

Symbol

Parameter

Units

Typ.

Max.

Input Capacitance on TTL Input Pins

pF

1.6

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. The optional series padding resistors (Rpad) help dampen load reflections. Typical Rpad values for mismatched loads range

between 25-75

Ω.

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

VCC_TTL

R

VBB 1.4 V

R

GND_TTL

VCC_TX

or

VCC_RX

ESD

PROTECTION

GND_TTL

VCC_TTL

R

R

R

O_TTL

I_TTL

GND

ESD

PROTECTION

VCC_TX

HS_OUT

R

0.01

0.01

Zo = 75

Ω

Zo = 75

Ω

VCC_TXHS

VCC_TXECL

GND

ESD

PROTECTION

-DOUT

+DOUT

150

150

RPAD

RPAD

GND_TXHS

+DIN

-DIN

ESD

PROTECTION

R

+

–

+

–

HS_IN

150

VCC_RX

GND

GND_RXHS

VCC_RXHS