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2

December 1998b

MICRF011

MICRF011

Micrel

Ordering Information

Part Number

Temperature Range

Package

MICRF011BN

-40

°C to +85°C

14-Pin DIP

MICRF011BM

-40

°C to +85°C

14-Pin SOIC

Pin Configuration (DIP and SOIC)

Pin Description

Pin Number

Pin Name

Pin Function

1

SEL0

Programs desired Demodulator Filter Bandwidth. This pin in internally pulled-up to VDD. 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).

4

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 22, MICRF001 Theory of Operation”.)

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.

7

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 118kohms (for REFOSC frequency ft=4.90MHz). Note that variation in source resistance with filter

selection no longer exists, as it does for the MICRF001. (See “Application Note 22, MICRF001 Theory

of Operation”, section 6.4). A standard

± 20% X7R ceramic capacitor is generally sufficient.

8

DO

Output data pin. CMOS level compatible.

9/10

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).

11

CAGC

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

(TC) ratio is nominally set as 10:1. Use of 0.47

µF or greater is strongly recommended for best range

performance. See “Application Note 22, MICRF001 Theory of Operation” for further information.

12

SEL1

Programs desired Demodulator Filter Bandwidth. This pin in internally pulled-up to VDD. See Table 1.

13

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 operated in FIXED mode, a crystal must be used; however in SWP mode, one may use either a

crystal or ceramic resonator. See “Application Note 22, MICRF001 Theory of Operation” for details on

frequency selection and accuracy.

14

SWEN

This logic pin controls the operating mode of the MICRF011. When SWEN = HIGH, the MICRF011 is in

SWP mode. This is the normal (default) mode of the device. When SWEN = LOW, the device operates

as a conventional single-conversion superheterodyne receiver. (See “Application Note 22, MICRF001

Theory of Operation” for details.) This pin is internally pulled-up to VDD.