DS32KHZ View Datasheet(PDF) - Dallas Semiconductor -> Maxim Integrated
Part Name
Description
Manufacturer
DS32KHZ Datasheet PDF : 8 Pages
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DS32kHz
The DS32kHz is packaged in a 36-pin ball grid array (BGA). It also is available in a 16-pin 0.300” SO and a 14-pin
encapsulated DIP (EDIP) module.
The additional PC board space required to add the DS32kHz as an option for driving a RTC is negligible in many
applications (see Figure 6) Therefore, adding the DS32kHz to new designs and future board revisions allows the
use of the DS32kHz where applications require improved timekeeping accuracy.
Figure 3. Block Diagram
VCC
Dallas
Semiconductor
Temperature DS32kHz
Measurement
VBAT
Power
Switching
Circuit
Power Control
P
32.768kHz
N
GND
OPERATION
The DS32kHz module contains a quartz tuning-fork crystal and an IC. When power is first applied, and when the
device switches between supplies, the DS32kHz measures the temperature and adjusts the crystal load to
compensate the frequency. The power supply must remain at a valid level whenever a temperature measurement
is made, including when VCC is first applied. While powered, the DS32kHz measures the temperature once every
64 seconds and adjusts the crystal load.
The DS32kHz is designed to operate in two modes. In the dual-supply mode, a comparator circuit, powered by VCC,
monitors the relationship between the VCC and VBAT input levels. When VCC drops below a certain level compared to
VBAT, the device switches over to VBAT (Figure 4A). This mode uses VCC to conserve the battery connected to VBAT
while VCC is applied.
In the single-supply mode, VCC is grounded and the unit is powered by VBAT. Current consumption is less than VCC,
because the comparator circuit is unpowered (Figure 4B).
Figure 4A shows how the DS32kHz should be connected when using two power supplies. VCC should be between
4.5V and 5.5V, and VBAT should be between 2.7V and 3.5V. Figure 4B shows how the DS32kHz can be used when
only a single-supply system is available. VCC should be grounded and VBAT should then be held between 2.7V and
5.5V. The VBAT pin should be connected directly to a battery. Figure 4C shows a single-supply mode where VCC is
held at +5V. See the frequency stability vs. operating voltage for information about frequency error vs. supply
voltage.
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