MEMS Ultra-Low Power Oscillator, 32.768 kHz Quartz XTAL Replacement

IM890 Series

ILSI America Phone 775-851-8880 ● Fax 775-851-8882 ●email: e-mail@ilsiamerica.com ●

www.ilsiamerica.com

Specifications subject to change without notice

Rev 05/17/16_B

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Page 4 of 10

Description

The 1.2V to 3.63V operating supply voltage range makes it an

ideal solution for mobile applications that incorporate a

low-voltage, battery-back-up source such as a coin-cell or

super-cap.

XTAL Footprint Compatibility (SMD Package)

The IM890 is a replacement to the 32 kHz XTAL in the 2.0 x

1.2 mm (2012) package. Unlike XTAL resonators, The ILSI

silicon MEMS oscillators require a power supply (Vdd) and

ground (GND) pin. Vdd and GND pins are conveniently placed

between the two large XTAL pins. When using the ILSI

Solder Pad Layout (SPL), the IM890 footprint is compatible

with existing 32 kHz XTALs in the 2012 SMD package. Figure

2 shows the comparison between the quartz XTAL footprint

and the ILSI footprint.

Figure 2 IM890 Footprint Compatibility with

Quartz Crystal Footprint

Frequency Stability

The IM890 is factory calibrated (trimmed) to guarantee

frequency stability to be less than 20 ppm at room

temperature and less than 100 ppm over the full -40°C to

+85°C temperature range. Unlike quartz crystals that have

a classic tuning fork parabola temperature curve with a

25°C turnover point, the IM890 temperature coefficient is

extremely flat across temperature. The device maintains

less than 100 ppm frequency stability over the full operating

temperature range when

the

operating

voltage

is

between 1.5 and 3.63V.

Functionality is guaranteed over the 1.2V - 3.63V operating

supply voltage

range.

However,

frequency

stability

degrades below 1.5V and steadily degrades as it

approaches the 1.2V minimum supply due to the internal

regulator limitations. Between 1.2V and 1.5V, the frequency

stability is 250 ppm max over temperature.

When measuring the IM890 output frequency with a

frequency counter, it is important to make sure the

counter's gate time is >100ms. The slow frequency of a 32

kHz clock will give false readings with faster gate times.

Power Supply Noise Immunity

The IM890 is an ultra-small 32 kHz oscillator. In addition to

eliminating external output load capacitors common with

standard XTALs, this device includes special power supply

filtering and thus, eliminates the need for an external

Vdd bypass-decoupling capacitor. This feature further

simplifies the design and keeps the footprint as small as

possible. Internal power supply filtering is designed to reject

AC-noise greater than ±150 mVpp magnitude and

beyond 10 MHz frequency component.

Output Voltage

The IM890 has two output voltage options One option is a

standard LVCMOS output swing. The second option is the

NanoDrive reduced swing output. Output swing is customer

specific and programmed between 200 mV and 800 mV. For

programming range is between 600 mV and 1.225V in 100 mV

mV and 800 mV. For example; a PMIC or MCU is internally

Simply select IM890 NanoDrive factory programming code to

be “D14” and the correct output thresholds will match the

downstream PMIC or MCU input requirements. Interface logic

will vary by manufacturer and we recommend that you review

the input voltage requirements for the input interface.

For DC-biased NanoDrive output configuration, the minimum

acceptable.

When the output is interfacing to an XTAL input that is inter-

nally AC-coupled, the IM890 output can be factory

programmed to match the input swing requirements. For

example, if a PMIC or MCU input is internally AC-coupled and

requires an 800mV swing, then simply choose the IM890

NanoDrive programming code “AA8” in the part number. It is

important to note that the IM890 does not include internal AC-

coupling capacitors. Please see the Part Number Ordering

section of the datasheet for more information about the part

number ordering scheme.

Power-up

The IM890 starts-up to a valid output frequency within

300 ms (150ms typ). To ensure the device starts-up within

the specified limit, make sure the power-supply ramps-up in

approximately 10 - 20 ms (to within 90% of Vdd). Start-up time

is measured from the time Vdd reaches 1.5V. For applications

that operate between 1.2V and 1.5V, the start-up time will be

longer.

IM890 NanoDrive

™

Figure 4 shows a typical IM890 output waveform (into a

10 pF load) when factory programmed for a 0.70V swing and

Example: