khz xtal, the old - wpg americas inc.typical pierce oscillator loop for rtc applications • uses a...
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kHz xtal, the OLD
kHz MEMS OSC, the NEW µA IoT • Wearables
Abracon has introduced its new series of watch-MEMS® kHz MEMS oscillators, featuring the World’s Smallest CSP (1.5x0.8mm) & SMD (2.0x1.2 mm) packages. This series is based on a proprietary MEMS resonator technology, yielding best-in-class kHz timing reference. These devices are ideally suited for tuning fork crystal replacement in space constrained designs. Optimized for the Wearable, IoT & Consumer solutions, these devices provide temperature stabilized alternative to tuning fork crystal based timing, while eliminating the oscillator loop capacitors, saving significant surface area, complexity & frequency variation over temperature.
Offered with both temperature stabilized (±75ppm or ±100ppm over -40°C to +85°C) version and temperature compensated (±5ppm, ±10ppm or ±20ppm over -40°C to +85°C) version; this series offers designers great flexibility to replace a typical tuning fork watch crystal with a precise 32.768kHz clocking solution.
Initial Tolerance Histogram
Initial Tolerance (ppm) TA = 25˚C Post Reflow
Num
ber o
f Dev
ices
Frequency Stability vs. Operating Temperature Range
Freq
uenc
y St
abili
ty (P
PM)
Temperature (˚C)
Core Current vs Operating Temperature Range
Core
Cur
eent
(uA)
Temperature (˚C)
Start-up Time
Volta
ge (V
)
Time (sec)
Series Description Package Size
ASTMTXK
Temperature compensa ted, ultra -
miniature 32.768kHz MEMS oscillator
1.54 x 0.84 x 0.6mm
ASTMKJ
Low -power, ultra -miniature 3 2.768kHz
MEMS oscillator, with Programmable Output
Swing
1.54 x 0.84 x 0.6mm
ASTMKH
Low -power, ultra -miniature 32.768kHz
MEMS oscillator, with Programma ble Output
Swing
2.0 x 1.2 x 0.6mm
ASTMK
Low -power, ultra -miniature
1Hz ~ 32.768kHz MEMS oscillator, with
Programmable Output Swing
1.54 x 0.84 x 0.6mm 2.0 x 1.2 x 0.6mm
ASTMK 06 Low -power,
ultra -miniature 32.768kHz MEMS oscillator
2.0 x 1.2 x 0.6mm
Vdd = 3.63V
Vdd = 1.5 - 1.8V
kHz xtal, the OLD
kHz MEMS OSC, the NEW µA IoT • Wearables
Why should designers consider watch-MEMS® for RTC Timing!!
Typical Pierce Oscillator Loop for RTC applications
• Uses a Tuning Fork Quartz Crystal• Requires (2) oscillator loop capacitors• Set-tolerance is contingent upon accurately matching the crystal plating load to the capacitance of the oscillator loop, best-case ±10 ppm• Frequency stability over -40°C to +85°C is worse than ±175 ppm• Total solution consumes the following surface area:
Pierce Oscillator Loop using watch-MEMS®
• No oscillator loop capacitors are needed• No by-pass capacitor is needed • Set-tolerance is typically better than ±5 ppm for temperature stabilized version and better than ±2.5 ppm for TCXO version• Frequency stability over -40°C to +85°C is typically better than ±50ppm for temperature stabilized version and ±5 pp maximum for TCXO version • ASTMK series is available with Factory Programmable Output Swing, enabling it to be the drop-in replacement for Tuning Fork Crystals• Total solution consumes the following surface area:
R (Feedback)
Integrated Inverter
Tuning Fork Quartz Crystal
Loop
Cap
acito
r #2
Loop
Cap
acito
r #1
GND
32.k
Hz C
LK
80% smaller than2.0 x 1.2mm SMD Quartz Solution
60% smaller than1.6 x 1.0mm SMD Quartz Solution
8 mm2
consumes
using 3.2 x 1.5mm(Crystal)
5 mm2
consumes
using 2.0 x 1.2mm(Crystal)
3 mm2
consumes
using 1.6 x 1.0mm(Crystal)