“Today, modern design companies are not only struggling to find smaller devices with lower power consumption, but they also hope to reduce costs for applications such as industrial automation, PCs, servers, and telecommunications equipment. The stumbling block to achieve these goals is that designers use a processor running at a single voltage, which needs to be connected to various peripherals or other subsystems operating at different voltages.
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Author: Chris Cockrill Texas Instruments
Today, modern design companies are not only struggling to find smaller devices with lower power consumption, but they also hope to reduce costs for applications such as industrial automation, PCs, servers, and telecommunications equipment. The stumbling block to achieve these goals is that designers use a processor running at a single voltage, which needs to be connected to various peripherals or other subsystems operating at different voltages. This requires convenient up-conversion of the voltage. This kind of frequency conversion is usually done using multiple discrete components. Let’s discuss why a single logic component using a single rail can perform voltage conversion efficiently and effectively while simplifying the design. In addition, we will also teach you how to conveniently perform up-down conversion.
The TI SN74LV1T series only needs one power rail to perform up-down voltage conversion. The device’s overvoltage tolerant input allows down-conversion of up to 5.5V for Vcc levels, which can be as low as 1.8V. In addition, this series also has a lower switching threshold, allowing it to be up-converted to the Vcc level, which can be as high as 5.5V (see Figure 1). This can solve the problem of requiring multiple voltage levels in a single application.
Figure 1: SN74LV1T can replace multiple discrete components
How to down-convert
The SN74LV1T series can greatly simplify down-conversion. Since the input tolerance is 5.5V at any effective Vcc, they can be used for down conversion. The input can be any level higher than Vcc, up to 5.5V, and the output is equal to the Vcc level, which can be as low as 1.8V. SN74LV1T is very unique: ICC current can be kept lower than or equal to the specified value during down conversion. The current consumption during frequency conversion is shown in Figure 3 below.
The SN74LV1T series can help realize various down-conversions:
Under 1.8V Vcc, from 2.5V, 3.3V or 5V to 1.8V
Under 2.5V Vcc, from 3.3V or 5V to 2.5V
Under 3.3V Vcc, from 5V to 3.2V
How to upconvert
Upconversion is actually very simple. The input switch threshold can be lowered, so the high-level input voltage can be much lower than the Vih of a typical CMOS. For example, if Vcc is 3.3V, then the typical CMOS switching threshold will be VCC/2 or 1.65V. This means that the input high level must be at least Vcc*.7 or 2.31V. On the SN74LV1T device, the input threshold of 3.3V Vcc is approximately 1V. This helps to up-convert signals with 1.8V Vih to Vcc levels as high as 3.3V. An example is shown in Figure 3.
The SN74LV1T series can help realize various up-conversions:
Under 1.8V Vcc, change from 1.2V to 1.8V
Under 2.5V Vcc, from 1.8V to 2.5V
Under 3.3V Vcc, from 1.8V or 2.5V to 3.3V
Under 5V Vcc, change from 2.5V or 3.3V to 5V
Figure 2: 3.3V Vcc switching threshold
In battery-powered equipment where power consumption is very important, the power consumption may be higher when the input is lower than Vcc. Figure 4 is an example of power consumption. If power consumption is the main consideration, be sure to consult the product manual.
Figure 3: Power consumption during conversion
The SN74LV1T series of devices can provide a simple way to perform functions and convert voltage levels when up and down conversion is required. A device in a small package can replace multiple discrete components without upconversion. The SN74LV1T series can ultimately simplify the design, which not only reduces board space, but also reduces costs.
Author: Chris Cockrill Texas Instruments
Today, modern design companies are not only struggling to find smaller devices with lower power consumption, but they also hope to reduce costs for applications such as industrial automation, PCs, servers, and telecommunications equipment. The stumbling block to achieve these goals is that designers use a processor running at a single voltage, which needs to be connected to various peripherals or other subsystems operating at different voltages. This requires convenient up-conversion of the voltage. This kind of frequency conversion is usually done using multiple discrete components. Let’s discuss why a single logic component using a single rail can perform voltage conversion efficiently and effectively while simplifying the design. In addition, we will also teach you how to conveniently perform up-down conversion.
The TI SN74LV1T series only needs one power rail to perform up-down voltage conversion. The device’s overvoltage tolerant input allows down-conversion of up to 5.5V for Vcc levels, which can be as low as 1.8V. In addition, this series also has a lower switching threshold, allowing it to be up-converted to the Vcc level, which can be as high as 5.5V (see Figure 1). This can solve the problem of requiring multiple voltage levels in a single application.
Figure 1: SN74LV1T can replace multiple discrete components
How to down-convert
The SN74LV1T series can greatly simplify down-conversion. Since the input tolerance is 5.5V at any effective Vcc, they can be used for down conversion. The input can be any level higher than Vcc, up to 5.5V, and the output is equal to the Vcc level, which can be as low as 1.8V. SN74LV1T is very unique: ICC current can be kept lower than or equal to the specified value during down conversion. The current consumption during frequency conversion is shown in Figure 3 below.
The SN74LV1T series can help realize various down-conversions:
Under 1.8V Vcc, from 2.5V, 3.3V or 5V to 1.8V
Under 2.5V Vcc, from 3.3V or 5V to 2.5V
Under 3.3V Vcc, from 5V to 3.2V
How to upconvert
Upconversion is actually very simple. The input switch threshold can be lowered, so the high-level input voltage can be much lower than the Vih of a typical CMOS. For example, if Vcc is 3.3V, then the typical CMOS switching threshold will be VCC/2 or 1.65V. This means that the input high level must be at least Vcc*.7 or 2.31V. On the SN74LV1T device, the input threshold of 3.3V Vcc is approximately 1V. This helps to up-convert signals with 1.8V Vih to Vcc levels as high as 3.3V. An example is shown in Figure 3.
The SN74LV1T series can help realize various up-conversions:
Under 1.8V Vcc, change from 1.2V to 1.8V
Under 2.5V Vcc, from 1.8V to 2.5V
Under 3.3V Vcc, from 1.8V or 2.5V to 3.3V
Under 5V Vcc, change from 2.5V or 3.3V to 5V
Figure 2: 3.3V Vcc switching threshold
In battery-powered equipment where power consumption is very important, the power consumption may be higher when the input is lower than Vcc. Figure 4 is an example of power consumption. If power consumption is the main consideration, be sure to consult the product manual.
Figure 3: Power consumption during conversion
The SN74LV1T series of devices can provide a simple way to perform functions and convert voltage levels when up and down conversion is required. A device in a small package can replace multiple discrete components without upconversion. The SN74LV1T series can ultimately simplify the design, which not only reduces board space, but also reduces costs.
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