QwikRadio

tm

3

October 1999

MICRF003

MICRF003

Micrel

Pin Description (Pin numbers for the 8-pin version are identified in parentheses)

Pin Number

Pin Name

Pin Function

1

SEL0

This pin, in conjunction with SEL1, programs the desired Demodulator Filter Bandwidth. This pin is internally

pulled-up to VDDRF. See Table 1.

2/3

VSSRF

This pin is the ground return for the RF section of the IC. The bypass capacitor connected from VDDRF to

VSSRF should have the shortest possible lead length. For best performance, connect VSSRF to VSSBB at the

power supply only (i.e., keep VSSBB currents from flowing through VSSRF return path).

(1)

VSSRF

This pin is the ground return for the IC. The bypass capacitor connected from VDDRF to VSSRF should have

the shortest possible lead length.

4

(2)

ANT

This is the receive RF input, internally ac-coupled. Connect this pin to the receive antenna. Input impedance is

high (FET gate) with approximately 2pF of shunt (parasitic) capacitance. For applications located in high

ambient noise environments, a fixed value band-pass network may be connected between the ANT pin and

VSSRF to provide additional receive selectivity and input overload protection. (See “Application Note TBD”.)

5

VDDRF

This pin is the positive supply input for the RF section of the IC. VDDBB and VDDRF should be connected

directly at the IC pins. Connect a low ESL, low ESR decoupling capacitor from this pin to VSSRF, as short as

possible.

6

VDDBB

This pin is the positive supply input for the baseband section of the IC. VDDBB and VDDRF should be

connected directly at the IC pins.

(3)

VDDRF

This pin is the positive supply input for the IC. Connect a low ESL, low ESR decoupling capacitor from this pin

to VSSRF, as short as possible.

7

(4)

CTH

This capacitor extracts the (DC) average value from the demodulated waveform, which becomes the reference

for the internal data slicing comparator. Treat this as a low-pass RC filter with source impedance of nominally

90kohms ( for REFOSC frequency Ft = 6.75MHz, see “Application Note TBD”). A standard

± 20% X7R

ceramic capacitor is generally sufficient.

8

N/C

Unused Pin

9

VSSBB

This is the ground return for the baseband section of the IC. The bypass and output capacitors connected to

VSSBB should have the shortest possible lead lengths. For best performance, connect VSSRF to VSSBB at

the power supply only (i.e., keep VSSBB currents from flowing through VSSRF return path).

10

(5)

DO

The output data signal. CMOS level compatible.

11

(6)

SHUT

A logic input for Shutdown Mode control. Pull this pin low to place the IC into operation. This pin in internally

pulled-up to VDDRF.

12

WAKEB

An output signal, active low when the IC detects an incoming RF signal, determined by monitoring for data

preamble. CMOS level compatible.

13

(7)

CAGC

Integrating capacitor for on-chip AGC (Automatic Gain Control). The Decay/Attack time-constant (TC) ratio is

nominally set as 10:1. Use of 0.47uF or greater is strongly recommended for best range performance. Use

low-leakage type capacitors for duty-cycle operation (Dip Tantalum, Ceramic, Polyester). (See “Application Note

TBD.)

14

SEL1

This pin, in conjunction with SEL0, programs the desired Demodulator Filter Bandwidth. This pin in internally

pulled-up to VDDRF. See Table 1.

15

(8)

REFOSC

This is the timing reference for on-chip tuning and alignment. Connect either a ceramic resonator or crystal

(mode dependent) between this pin and VSSBB, or drive the input with an AC coupled 0.5Vpp input clock. Use

ceramic resonators without integral capacitors. Note that if operating in FIXED mode, a crystal must be used;

however in SWP mode, one may use either a crystal or ceramic resonator. See “Application Note TBD” for

details on frequency selection and accuracy.

16

SWEN

This logic pin controls the operating mode of the MICRF003. When SWEN = HIGH, the MICRF003 is in SWP

mode. When SWEN = LOW, the device operates as a conventional single-conversion superheterodyne

receiver. (See “Application Note TBD” for details.) This pin is internally pulled-up to VDDRF.

SEL0

SEL1

Demodulator Bandwidth (Hz)

SWP Mode

FIXED Mode

1

1

6000

22400

0

1

3000

11200

1

0

1500

5600

0

0

750

2800

Table 1

Nominal Demodulator (Baseband) Filter Bandwidth

vs. SEL0, SEL1 and Mode