TPS3808G19DBVT

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Abstract: TPS3808G19DBVT is a low quiescent current voltage supervisor with an adjustable delayed reset. This article provides an introduction to TPS3808G19DBVT application field and its working principle.

Introduction to TPS3808G19DBVT

TPS3808G19DBVT is a micro-power voltage supervisor with an adjustable delayed reset from Texas Instruments. It provides supervisory level-setting and push-pull reset active-low/ RESET OUT pulse generate functions. This product is available in SOT23-5 packaging, in a variety of operating voltages and is rated over the industrial temperature range (–40°C to 85°C).

The internal delay time of TPS3808G19DBVT is programmed by an external capacitor connected to the TIMER pin. When VCC comes on, TPS38008G19DBVT monitors it immediately. A reset can be forced at any time by grounding the RESET pin. In addition, the RESB pin can be toggled to produce a reset pulse that can be used to reset other ICs, for example external CPU.

TPS3808G19DBVT Application Field

TPS3808G19DBVT can be used in a variety of application field, including consumer electronics, telecommunications and automotive data bus protection. It is an ideal choice for designers who need a high accuracy and low power voltage supervisor with a programmable reset delay.

The TPS3808G19DBVT is most suitable for monitoring and regulating VCC supplies, for example, in devices that may be clocked by high-speed gates whose power supply is highly sensitive to noise or transients，or in systems with multiple voltage rails that have different start-up and reset requirements. By using TPS3808G19DBVT, the designer can now be sure that each of these rail voltages are monitored and reset accordingly, thus providing a fully robust system.

TPS3808G19DBVT Working Principle

The working principle of TPS3808G19DBVT is based on the successive comparison of an internally generated reference voltage and the input voltage. This comparison is done by means of a differential amplifier/shunt switch combination, as shown in Figure 1. The reference voltage is established by a precision bandgap reference, while the four comparators Provides active-low/RESET OUT, active-low/RESET OUT and open-drain RESET with adjustable delay.

Figure 1: TPS3808G19DBVT Circuit Diagram

In Figure 1, VDD is the power supply for TPS3808G19DBVT, VINx is the voltage that needs to be supervised, and VDD is the voltage to which VINx must be monitoring. The comparison will be donewhen the power is switched on. When VINx is higher than VDD, the shunt between pin 3 and 4 will open, this will lead to output RESETx fixed in low state, and the RESETOUT pins will pull low. Then the differential amplifier will compare the reference voltage at pin 3 node and the VDD input voltage at pin 2 node, when VDD is lower than the reference voltage, the switches at node A and node B will both be opened, and the voltage at node C will be pulled-up through R1 resistor to the VDD voltage. As the result of this pulling-up, the RESETOUT pin will be pulled to high state to reset the system.

When VINx is higher than VDD, node A will be pulled low, node B will remain high and the voltage at node C will remain high. Thus, the RESETOUT pin will remain in its low state. This process is a continuous loop until VDD increases to the reference voltage value.

The TPS3808G19DBVT also offers an adjustable delayed reset for system guard. The delay is adjustable by connecting a capacitor to the TIMER pin. This capacitor can also be used to modulate the reset period by connecting it to the reset line.

In conclusion, TPS3808G19DBVT is an ideal choice for designers needing a low power, high accuracy voltage supervisor with adjustable delayed reset.

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