February 9, 2000

3

MICRF004/RF044

MICRF004/RF044

Micrel

Pin Description

Pin Number

Pin Number

Pin Name

Pin Function

16-Pin Pkg.

8-Pin Pkg.

1

SEL0

Bandwidth Selection Bit 0 (Input): Configure with SEL1 to set the desired

demodulator filter bandwidth. See Table 1. Internally pulled-up to VDDRF.

2, 3

1

VSSRF

RF [Analog] Return (Input): Ground return to the RF section power supply.

See “Application Information” for bypass capacitor details.

4

2

ANT

Antenna (Input): High-impedance, internally ac coupled receiver input.

Connect this pin to the receive antenna. This FET gate input has approxi-

mately 2pF of shunt (parasitic) capacitance. See “Applications Information”

for optional band-pass filter information.

5

3

VDDRF

RF [Analog] Supply (Input): Positive supply input for the RF section of the

IC. VDDBB and VDDRF should be connected together directly at the IC

pins. Connect a low ESL, low ESR decoupling capacitor from this pin to

VSSRF, as short as possible.

6

VDDBB

Base-Band [Digital] Supply (Input): Positive supply input for the baseband

section of the IC. VDDBB and VDDRF should be connected together at the

IC pins.

7

4

CTH

[Data Slicing] Threshold Capacitor (External Component): Capacitor

extracts the dc average value from the demodulated waveform which

becomes the reference for the internal data slicing comparator. See “Appli-

cations Information” for selection.

8

NC

not internally connected

9

VSSBB

Base-Band [Digital] Return (Input): Ground return to the baseband section

power supply. See “Application Information” for bypass capacitor and layout

details.

10

5

DO

Digital Output (Output): CMOS-level compatible data output signal.

11

6

SHUT

Shutdown (Input): Shutdown-mode logic-level control input. Pull low to

enable the receiver. This input has an internal pulled-up to VDDRF.

12

WAKEB

Wakeup (Output): Active-low output that indicates detection of an incoming

RF signal. Signal is determined by monitoring for data preamble. CMOS-

level compatible.

13

7

CAGC

AGC Capacitor (External Component): Integrating capacitor for on-chip

AGC (automatic gain control). The decay/attack time-constant (

τ) ratio is

nominally 10:1. See “Applications Information” for capacitor selection.

14

SEL1

Bandwidth Selection Bit 1 (Input): Configure with SEL0, programs to set the

desired demodulator filter bandwidth. See Table 1. Internally pulled-up to

VDDRF.

15

8

REFOSC

Reference Oscillator (External Component or Input): Timing reference for

on-chip tuning and alignment. Connect either a ceramic resonator or crystal

(mode dependent, see “Application Information”). between this pin and

VSSBB, or drive the input with an ac-coupled 0.5Vpp input clock.

16

SWEN

Sweep-Mode Enable (Input): Sweep- or fixed-mode operation control input.

When VSWEN is high, the MICRF004 is in sweep mode; when SWEN is

low, the receiver operates as a conventional single-conversion superhetero-

dyne receiver. This pin is internally pulled-up to VDDRF.