Application note

CME6005
Receiver IC

The CME6005 is a BiCMOS integrated straight through receiver with build in very highsensitivity for the time signal transmitted from WWVB, DCF77, JJY, MSF and HBG. The
receiver is prepared for single-and dual band (by using additional capacitor matching pin)
reception.
The CME6005 can serve as a direct substitution to some radio controlled receiver IC’s thatwas on the market, but some particular attention need to be given to ensure the best ofperformance.
For example:
DCF 100ms pulses

1. Output Stages
One main difference between the CME6005 and some other receiver IC’s is the connections
at the analog output stages, sometimes called TCO or OUT pins.
The serial signal of the time-code transmitter given out from the TCO or TCON can bedirectly decoded by a micro controller. TCO gives out a direct demodulated wave form fromthe IC and the TCON gives out an inverted waveform from the IC.
If TCO is connected, TCON must be open, and vice versa. However, no pull up or pull
down resistors are required at these output pins. Addition of any components at the outputpins may overload the output stage and cause degradation in sensitivity.
DCF 100 ms pulses

SPEC No.

RevisionState

C-MAX printedVersionPage

CME6005-AN001

A1.0

21.09.04

03.05.07

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Application note AN001 for CME6005

2. AGC Hold (HLD)
AGC hold mode: HLD = high (VHLD = VCC) means no hold, HLD = low (VHLD = 0) applies
hold action to the internal automatic gain control (AGC) inside the CME6005. This can beused to prevent the AGC from peak voltages, created by e.g. a stepper motor.
One important note on this pin is that the AGC HLD pin MUST NOT be left open. It must beconnected to the defined HIGH (VCC or VDD) or defined LO (GND).

3. Use of QC pin
The QC pin is only used when two high selectivity crystals, with a total shunt capacitance of >1.6 pF (including internal capacitor + parasitic capacitance on PCB) are used for dual
frequency applications on the CME6005.
If only one crystal is used (i.e. for single band applications), this QC pin should be left
open and not bonded to the PCB.
For dual frequency applications, if both crystals connected in parallel gave a total shunt
capacitance of, for example 2.9 pF. Then a capacitor of 2.9 – 1.6 pF = 1.3 pF should beconnected between the QC and the QIN pin. This compensation technique works mostfavorably for crystals with a reasonable steep selectivity curve.

SPEC No.

RevisionState

C-MAX printedVersionPage

CME6005AN001

A1.0

21.09.04

03.05.07

English2 of 4

C-MAX Time Solutions

Application note AN001 for CME6005

4. Power On pin (PON)The CME6005 is active LO, which means that the receiver IC will be powered on if a LOsignal (or GND) is applied to the PON pin. The receiver IC will be turned off if a HI signal (orVCC) is applied to the PON pin. Do not in any case leave this pin open.

5. Antenna input characteristics
The CME6005 requires a resonant resistance at the antenna inputs IN1 and IN2 of 40kΩ to 100 kΩ . This can be achieved by a variation of the L/C-relation in the antenna circuit.
In order to achieve this resonant resistance, we recommend to use antenna capacitors of avalue between 2.2nF and 6.8nF, and thus from simple LC resonance circuitry calculation, will
not require an antenna inductance of above 4 mH (which is required for some other receiver
ICs on the market).

6. DEM and PK capacitors
The DEM capacitor influences the stability of the demodulator output. The PK capacitor value
influences the AGC regulation time. Note that the suggested values may be different fordifferent PCB layouts and some fine tuning of the DEM capacitor may be necessary toachieve the optimum sensitivity. However, it is not recommended to change the PK value.

Cdem

Cpk

DCF

47nF

4.7µF

WWVB

100nF

4.7µF

JJY60

100nF

4.7µF

MSF

100nF

4.7µF

JJY40100nF

4.7µF

SPEC No.

RevisionState

C-MAX printed

VersionPage

CME6005AN001

A1.0

21.09.04

03.05.07

English3 of 4

C-MAX Time Solutions

Application note AN001 for CME6005

6. Ground Connections of IC
There are two ground connections required to the CME6005. One is the ground pin on theIC and the other is the substrate to the IC. To ensure optimal performance, it is importantthat these two grounds should not be connected together through one signal ground via hole.
Two separate via holes to ground plane will give a better performance in terms ofsensitivity.

Ground Connection Vias

Disclaimer of Warranty
Information furnished is believed to be accurate and reliable. However C-MAX assumes no responsibility,neither for the consequences of use of such information nor for any infringement of patents or other rights of third parties, which may
result from its use. No license is granted by implication or otherwise under any patent or patent rights of C-Max. Specifications mentioned inthis publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. C-MAX
products are not authorized for use as critical components in life support devices without express written approval of C-MAX.

Note
It is not given warranty that the declared circuits, devices, facilities, components, assembly groups or treatments included herein are freefrom legal claims of third parties.
The declared data are serving only to description of product. They are not guaranteed properties as defined by law. The examples are given
without obligation and cannot given rise to any liability.
Reprinting this data sheet - or parts of it - is only allowed with a license of the publisher.
C-MAX reserves the right to make changes on this specification without notice at any time.

C-MAX Time Solutions GmbH
Carl-Zeiss-Str. 1374078 Heilbronn
Tel.: +49-7066-900400
Fax: +49-7066-9004029
e-mail: contact@c-max-time.com
Data sheets can also be retrieved from our Internet homepage: www.c-max-time.com

SPEC No.

Revision

StateC-MAX printedVersionPage

CME6005AN001

A1.0

21.09.04

03.05.07

English4 of 4