Press release: RV-3028-C7



Picture RV-3028-C7

The RV-3028-C7 is the first ultra-low power RTC-module requiring just 40nA!

The new Real-time Clock Module RV-3028-C7 sets the new benchmark for lowest power consumption: 40 nA at a supply 3 V. The high accuracy of ±1 ppm at room temperature eliminates any calibration during manufacturing. The tiny package of just 3.5 x 1.5 x 0.8 mm combines the quartz crystal with the RTC circuit, offering also an integrated battery-back-up switch. The extreme low power consumption allows using MLCC capacitors to cover the back-up time. Together with an event detection input it features all the prerequisites for Wearables, Medical Healthcare and power sensitive IoT applications.

  • Industries lowest current consumption of only 40 nA at 3 V supply
  • Factory calibrated time reference ±1.0 ppm at 25°C
  • Integrated 32.768 kHz Quartz Crystal
  • Event input for time-stamping during system power-down
  • Battery back-up switch with trickle charge ideal also for MLCC and Supercap
  • Wide voltage range 1.2 to 5.5V
  • Ultra-miniature ceramic SMD package: 3.2 x 1.5 x 0.8 mm
  • Provides year, month, date, weekday, hours, minutes and seconds
  • 32 bit Unix time counter e.g. for security code calculations
  • I²C interface 400 kHz

Specific link to the home page:

Markus Hintermann, International Product Manager at Micro Crystal AG in Switzerland quotes: "The RTC-Module RV-3028-C7 is the new mile stone in the field of time references. The combination of timing with back-up circuitry featuring the industry's lowest power consumption extends the autonomy in harsh conditions and will become the time reference of choice for Wearable and IoT applications."


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Ins CM9V-T1A Picture

Micro Crystal ultra-thin 32.768 kHz Crystal improves oscillator reliability

Advanced package geometry enhances mechanical flexibility in products on-the-go

Grenchen, Switzerland, May 1, 2018 – Micro Crystal AG, the ultra-low-power, low-voltage solution provider today announced the next step in miniaturization: CM9V-T1A 0.3: a 32.768 kHz Quartz Crystal with a maximum thickness of 0.35 and a foot print of just 1.6 x 1.0 mm
This new tiny geometry enhances the circuitry in application where bending radii are critical. It complements the new bendable thin film batteries from The crystals are ideal for:

   •   Smart cards
   •   E-textile
   •   Wearables and activity bands
   •   Embedded modules
   •   Health care, e-medicine treatment sticking plaster

The 32.768 kHz Crystal family has proven track record in thousands of applications worldwide.
Wearables, IoT, Industrial, Automotive, Healthcare and Consumer

Type Frequency Size , l x w x h Status

CM9V-T1A 0.3 32.768 kHz 1.6 x 1.0 x 0.3 mm High volume production ramp-up
CM8V-T1A 0.3 32.768 kHz 2.0 x 1.2 x 0.3 mm High volume production

Detailed information for Low Frequency Crystals

Achieving Lowest Power consumption on system level: the RTC module enables it!

Author: Markus Hintermann, Product Manager Micro Crystal AG                                              Jan 30. 2018



IoT, Internet of things opens up a wealth of new applications and generates hunger for more functions to monitor or control. Unfortunately this goes often in line with increased power consumption. This is the starting point for a systematic check the power demand. The various function blocks draw specific maximum currents. Fortunately not all the functions need to be operating continuously at peak performance. The goal is switching off everything not required at the very moment. The device, always staying on, needs to be drawing ultra-low power. Why not consider an RTC, since it stays on anyhow.

State of the art RTC modules consume as low as 60 nA at full operation. Such a RTC tracks the time of the day and has the ability to periodically turning on the system controller to check for action. Cutting down the overall current demand by >90 % has been proven to be often possible.

This article not only pin points the neuralgic and sensitive points in applications where additional current could leak, but also proposes measures for reducing the impact.


1.   Low Power ≠ Low power
2.   Comparison LED, passive LCD, MCU low power, RTC, low power RTC
3.   Partitioning for low power on system level
4.   Controlling the activity levels
5.   Selecting the key element, the RTC-Module
6.   Results and conclusions

1 Low Power ≠ low power

Today everything claims to be low power (LP). The next generation of an application is likely consuming little less power and already the LP label is attached.
Put in context: for battery operated systems the actual current consumption must be considered in relation to the battery capacity.

1.1 Current consumptions

Wearable, portable and many applications in the IoT space are forced to use the least amount of energy. Utilizing a low supply voltage is a good starting point, since most dissipation have ohmic characteristic: Reducing the voltage by a factor of 1.5 (e.g. 5.0  3 V) will cut the power in half. Selecting and optimizing the circuitry for lowest power consumption. Comparison of different elements is illustrating
the magnitude of the individual current consumption: The microcontroller unit (MCU) doesn't need to be running continuously!

2 Comparison LED, passive LCD, MCU low power, RTC, low power RTC

Assumption: 3.0 V supply voltage

Component current duty cycle average current comment
a) LED 10 mA 20 %       2000      μA blinking LED *
b) MCU low power 3 mA 10 % 300      μA Main action ongoing
c) MCU sleep mode 50 μA 50 % 25      μA
d) MCU RTC only 2 μA 100 % 2      μA RTC always stays on
e) RTC module 130 nA 100 % 0.13  μA RTC always stays on
RTC module 60 nA 100 % 0.06  μA RTC always stays on
* use of high efficient LEDs delivering same brightness already at 2mA (average 200 μA)

2.1 Battery capacities

Li-ion batteries (or Li battery packs) are very popular exploiting several parameters:
- The supply voltage is relatively high with 4.2 ...3.9 V, ideal to power functions with peak power
- Have high capacity per volume and also high capacity per weight
- Respectable high number of charge / discharge cycles
- Offered with various capacities e.g. several 1000 mAh

Using a second battery is ideal for keeping the system alive all the time. Key parameters are:
- Low leakage and therefore small self-discharge
- Ideal to feed a low power RTCs and memory functions

As back-up batteries coin cell batteries are enjoying popularity:
e.g. primary cell Li 2032 CR2032 MFRR, it is
- Small size:  20 mm, thickness 3.2 mm
- Constant supply voltage: 3.0 V
- Capacity: 225 mAh
- Low cost: a few cents in high volumes
- large number of suppliers: Renata, Duracell, Varta....
- high availability

2.2 Operating time

Current consumption over time:
Example: Wireless remote monitoring module. The action: the sensor is periodically checked, upon changes correction in the control system are executed and upon large deviations the values are transmitted to the base station. (Implementation A) In a typical case the action occurs at random points in time a). The action b) is consuming the largest current. The microcontroller c) is running all the time to be ready in time to catch necessary action. The RTC, integrated in the microcontroller d), allows to time stamp the actions. The envelope summarizes all currents e).

With the help of the LOW POWER RTC module (Implementation B) the microcontroller is only turned on periodically to sample if any action is required c'), the remaining time it is put back in hibernation mode, the average current c'') is therefore reduced to the technical possible minimum. In actual cases the time of action (on) is likely only of short duration, a tiny fraction of the overall time period, therefore the savings f) represent the major part.

Achieving Lowest Power consumption on system level 9

3 Partitioning for low power on system level

Considering the architecture for power distribution early in the design phase proofed to be a good practice. The supply lines should be routed the way that the different functional blocks can be fully switched off.

3.1 Generic example of a process monitoring block

a) Ideally all sensors are activated continuously (1000s times per second), but is this crucial? A closer look at each individual block explores potential to reduce the power consumption. Just stretch the time between sampling

b) Sensor 1 needs to be read only once per minute as long as the temperature is <55°C, above 55°C it must be checked every 10s

c) Sensor 2 The water level cannot change fast, so checking it every 15 min is sufficient

d) Communications The module will communicate once per day at a fixed time or immediately when a parameter is exceeding critical limits.

3.2 Critical points

After a supply is switched off check all the lines in respect to leakage currents. Standard FET switches can easily be leaking in the order of several μA. Communication lines with open drain configuration are also a potential source. Make sure the pull-ups are connected to the supply of the controller. Diodes used for switching supplies have to be low leakage Schottky type.
Test frequency outputs must be switched off and configured for lowest power consumption.

4 Controlling the activity levels

Lowest system power consumption is reached when:
- Only one ultra-low power device is staying on all the time, controlling the periodic wakeup and keeping the time
- all other blocks are switched off or if not feasible
- the blocks need to put in hibernation or lowest power idling mode

This could mean that >>95% of the time the only powered circuit is the RTC-module.

Achieving Lowest Power consumption on system level 91


5 Selecting the key element: the RTC Module

RTC modules are superior to general purpose RTC with separate Xtal, especially when used in IoT and power critical applications. Integrating the RTC circuit with the 32 kHz crystal into a module enhances minimal 5 parameters:

- Higher accuracy since the crystals is matched with the oscillator and trimmed accordingly. Tolerance at room temp is limited to ±2 to ±20 ppm,
  versus a RTC with external Crystal results in    ±30 ... 35 ppm due to matching spreads
- The form factor is much smaller, about the same size as a crystal in a standard package: 1.5 x 3,2mm
- Since the oscillator circuit is in the hermitically sealed package and no high impedance contacts are accessible outside, it withstands harsh
  environmental conditions like moisture and contamination dust. The close proximity of crystal and RTC circuit reduces the susceptibility to spurious signal coupling.
- The design of the package guarantees an excellent temperature tracking. This behavior is the base for accurately compensating the quartz's
  parabolic temperature characteristics. A tolerance of ± 3 ppm respectively 2 seconds / week can be expected from -40°C to +85°C.
- Additional features like Time-stamp or integrated switch for battery back-up are also available.
- The standalone RTC-module is able to act as fully independent watchdog to supervise the software during execution.

RTC modules ideal for saving power on application level:

Achieving Lowest Power consumption on system level 92


6 Results and conclusions

There are numerous of applications requiring high computing power at once to digest the data and performing the special task for a very short time. Afterwards the system can fall back to idling mode. Adding a dedicated low power RTC module for scheduling the wake-ups cuts the power consumption to its minimum.

Achieving Lowest Power consumption on system level 93


Achieving Lowest Power consumption on system level 94Combining the microcontroller with a low power
RTC module increases the system performance:
- Lowest power budget
- Saves on cost for the back-up power source:
  requiring a smaller battery
- Accurate time
- Autonomous watch-dog function











About the author:

Achieving Lowest Power consumption on system level 95 Markus Hintermann,  

  In depth experience in applications of peripheral circuit from Real-Time
  Clocks, LCD drivers to capacitive touch switches.

  Technical Marketing and Sales Manager at Micro Crystal in Switzerland

  Micro Crystal
  Muehlestrasse 14
  2540 Grenchen Switzerland
  This email address is being protected from spambots. You need JavaScript enabled to view it.  

  +41 79 475 74 82,