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Level Shifter
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With GreenPAK™, getting different voltage domains working together, efficiently and with the flexibility of programmable mixed-signal, is a snap.
Often full-featured, power-efficient systems contain subsystems with different voltage requirements. For example, a wearable may normally operate at 1.8 V, but when charging, portions of the design will operate at the USB standard 5 V. Similarly, the display may operate at a different voltage than the sensors. Often, a number of discrete passive or fixed-function level shift devices are needed to make these voltage domains work together.
The best solution for this is any GreenPAK Dual Supply part number.
GreenPAK Benefits for Level Shift
GreenPAK Enhances Effectiveness with Dual Supply
- Dual Supply enables high efficiency level-shift without the need for external pull-up resistors supporting 1.8 V to 5.0 V for VDD and 1.8 V to VDD for VDD2
GreenPAK Maximizes Flexibility
- Configurable GPIO – Pull-up/pull-down resistors, Push-Pull, Open drain, etc.
- Flexible GPIO routing – Ensuring the least complexity in PCB routing
- Integration of many components – Generating custom timing and logic to further eliminate external components while bridging voltage domains and signal requirements
GreenPAK Ensures System Stability
- Zero code as implementing features in hardware ensures stability
- Integration of many components ensuring fewer points of failure
GreenPAK Lowers Power Consumption
- Low power consumption allows GreenPAK continuously operate without ruining power budget
GreenPAK Reduces Board Size
- Being as small as 1.2 mm² it is a perfect solution for mobile and wearable electronics
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Uni-directional
The simplest form of level-shift is uni-directional. Shifting a single direction, up or down, is easy in GreenPAK since all GPIO can be configured as inputs or outputs
Key Design Considerations
Number of Signals – GreenPAK can support up to 9 inputs/8 outputs on a single voltage domain
IO Configuration – Configurable pull-up / pull-down resistors on GreenPAK’s GPIO make communicating with any IC a snap
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Example 1. Uni-directional level-shift implemented in GreenPAK
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Example 1. Timing Diagram
Bi-directional with Dedicated Ports
Similar to uni-directional, using GreenPAK’s configurable GPIO to dedicate specific pins or groups of pins as input or output is easy. Each pin tied to a specific voltage domain can be configured independently allowing information to flow from lower to higher VDD or higher to lower VDD
Key Design Considerations
Number of Signals - GreenPAK can support up to 9 inputs/8 outputs on a single voltage domain
IO Configuration - Configurable pull-up / pull-down resistors on GreenPAK’s GPIO make communicating with any IC a snap
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Example 2. Bi-directional level-shift with dedicated ports implemented in GreenPAK
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Example 2. Timing Diagram
Bi-directional with External Direction Indicator
With GreenPAK it is also possible to dual-purpose certain GPIO as digital input AND output using the output enable pin to control the direction.
Key Design Considerations
Direction Signal Polarity – Using GreenPAK’s integrated LUTs configured as an inverter can accommodate any signal polarity
Direction Signal Origin – With GreenPAK, the direction signal input can be from either voltage domain
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Example 3. Bi-directional level-shift with external direction signal implemented in GreenPAK
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Example 3. Timing Diagram
Bi-directional, Auto-sensing
Using GreenPAK’s configurable digital and timing resources, it is even possible to implement an auto-sensing, bi-directional, level-shift solution such as the I2C Level-shift shown in AN-1104.
Key Design Considerations
Response Time – GreenPAK is capable of up to 400 kHz standard I2C
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Example 4. Auto-sensing bi-directional I2C level-shift
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Example 4. AN-1104 - I2C Level Shift in SLG46620V
Dual Supply GreenPAK
GreenPAK can often implement multiple functions in one small device. This isn’t limited to level-shift applications. Just one GreenPAK device can implement glue logic, timing adjustment, reset, power sequencing, LED control, and more depending on design requirements and resource configuration.
Below is a list of our Dual Supply GreenPAK devices and the number of GPIO dedicated to each voltage domain.
| Part Number | VDD IO | VDD2 IO |
|---|---|---|
| SLG46121V | 5 | 4 |
| SLG46535V | 7 | 4 |
| SLG46538V | 9 | 8 |
| SLG46621V | 9 | 8 |