TMS38054

RING INTERFACE DEVICE

SPWS008C – APRIL 1991 – REVISED MAY 1997

4

POST OFFICE BOX 655303

Terminal Functions (Continued)

TERMINAL

I/O/E†

TYPE‡

DESCRIPTION

NAME

NO.

I/O/E†

TYPE‡

DESCRIPTION

SPSW

7

I

T

Speed switch. SPSW specifies the token-ring data rate.

High = 4-Mbps data rate

Low = 16-Mbps data rate

STERES

16

E

N

Static timing error resistor. STERES allows connection to an external resistor for adjusting the

static-timing error.

VCCA1§

11

Positive supply voltage for VCO and filter input

VCCA2§

41

Positive supply voltage for receiver circuits

VCCB§

4

Positive supply voltage for input and output buffers

VCCD§

21, 33

Positive supply voltage for digital circuits (5 V)

VCOGAN

9

E

N

VCO gain resistor. VCOGAN allows connection to an external resistor for setting the VCO gain.

WDTCAP

25

E

N

Watchdog timer capacitor. WDTCAP allows connection to an external capacitor, which sets the

watchdog-timeout period.

WFLT

26

O

T

Phantom-wire-fault. WFLT provides an indication of the presence of a short circuit or open on

PHOUTA or PHOUTB.

High = No fault

Low = Open or short

WRAP

36

I

T

Internal-wrap mode control. WRAP allows the TMS38054 to be placed in the loopback-wrap

mode for adapter self test.

High = Normal ring operation

Low = Transmit data drives the receive data.

XTAL

23

I

T

Crystal-oscillator input. XTAL (normally externally gated by FRAQ) is used to synchronize the

PLL. XTAL is 32 MHz for 16-Mbps ring, and 8 MHz for 4-Mbps ring.

† I = input, O = output, E = provides external component connection to the internal circuitry for tuning

‡ T = TTL signal, N = non-TTL signal, D = differential drive or data

§ These terminals should be connected to a single power or ground plane as appropriate.