LP3470 Datasheet, PDF (10/22 Pages) National Semiconductor (TI) – Tiny Power On Reset Circuit

LP3470
SNVS003G – JUNE 1999 – REVISED APRIL 2016
8 Application and Implementation
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NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The LP3470 is a micropower CMOS voltage supervisor that is ideal for use in battery-powered microprocessor
and other digital systems. It is small in size and provides maximum adjustability for power-on-reset (POR) and
supervisory functions, making it a good solution in a variety of applications. The LP3470 is available in six
standard reset threshold voltage options, and the reset time-out period is adjustable using an external capacitor
providing maximum flexibility in any application. This device can ensure system reliability and ensures that a
connected microprocessor will operate only when a minimum V_in supply is satisfied.
8.2 Typical Application
The LP3470 can be used as a simple supervisor circuit to monitor the input supply to a microprocessor as shown
in Figure 10.
Figure 10. Power-On Reset Circuit
8.2.1 Design Requirements
For this design example, use the parameters listed in Table 1 as the input parameters.
Table 1. Design Parameters
DESIGN PARAMETER
Input supply voltage
Reset threshold voltage
External pullup resistor
External reset time-out period capacitor
Reset time-out period
EXAMPLE VALUE
0.5 to 5.5 V
2.63 V, 2.93 V, 3.08 V, 3.65 V, 4 V, 4.38 V, 4.63 V
0.68 to 68 kΩ
C₁ = 1 nF
2 ms
10
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