Dual power supply level shifter
Unidirectional signal level down / up can be achieved with a single power supply device with an input tolerant function, or a single power supply device with a TTL input function.
However, if fine signal level conversion is required or if bidirectional level conversion is required, the ideal device to use is a dual power level shifter.
Unidirectional up translation (dual-supply level shifters)
If you need to set input and output voltage levels in a flexible manner, it is recommended to use a dual-supply level shifter IC incorporating a logic-level converter.
A wide range of input and output voltage levels can be set when VCCA < VCCB.
Dual-supply level shifter ICs are suitable particularly for up translation in the low-voltage region that cannot be handled with LVTTL.
1.2 V → 1.8 V
1.5 V → 2.5 V
1.8 V → 3.3 V
Unidirectional dual-supply level shifters
Series |
Supply Voltage VCCA |
Supply Voltage VCCB |
Input Voltage |
Drive Capability (Output Current) |
Operating Frequency |
Level-Shifting Examples |
|
|---|---|---|---|---|---|---|---|
Level Shifters |
1.1 to 2.7 V |
1.65 to 3.6 V |
VCCA×0.65 V |
±12 mA |
Up to 64 MHz |
1.2/1.5 V → 1.8 V 1.2/1.5/1.8 V → 2.5 V 1.2/1.5/1.8/2.5 V → 3.3 V |
|
| TC7SPN3125TU (1-bit) TC7WPN3125FK (2-bit) |
1.1 to 2.7 V |
1.65 to 3.6 V |
VCCA×0.65 V |
±3 mA |
Up to 34 MHz |
||
1.1 to 2.7 V |
VCCA to 3.6 V |
VCCA×0.65 V |
±3 mA |
Up to 132 MHz |
1.2 V → 1.5 V 1.2/1.5V → 1.8 V 1.2/1.5/1.8 V → 2.5 V 1.2/1.5/1.8/2.5 V → 3.3 V |
||
A unidirectional dual power level shifter is ideal when a fine signal level conversion is required. Dual power supplies, VccA side and VccB side, are required, but since the level conversion circuit is built in, more flexible voltage level conversion is possible. It is especially effective for level conversion in the low voltage range, which cannot be achieved with LVTTL. Since the TC7SP / WP series is guaranteed to operate from 1.1V on the VccA side, it is possible to upgrade from a 1.2V system to a 1.8V or 3.3V system.
Bidirectional up/down translation (dual-supply bus buffers)
- Dual-supply level shifters incorporating logic-level converters
- Three-state buffers with an output drive capability
- Signal direction controlled via the DIR input
- Operating frequency of several tens of MHz
Bidirectional dual-supply level shifters (bus buffers)
Series |
Supply Voltage VCCA |
Supply Voltage VCCB |
Control Pin |
Drive Capability (Output Current) |
Operating Frequency |
Additional Features |
Level-Shifting Examples |
|
|---|---|---|---|---|---|---|---|---|
CMOS Logic ICs |
TC74LCX163245 |
4.5 to 5.5 V |
2.3 to 3.6 V |
VCCB side |
±24 mA |
Up to 71 MHz |
- |
2.5/3.3 V ⇔ 5.0 V |
TC74LCXR163245 |
4.5 to 5.5 V |
2.3 to 3.6 V |
VCCB side |
±12 mA |
Up to 59 MHz |
Series resistor for noise reduction |
2.5/3.3 V ⇔ 5.0 V |
|
TC74LCX164245 |
2.3 to 3.6 V |
4.5 to 5.5 V |
VCCB side |
±24 mA |
Up to 86 MHz |
- |
2.5/3.3 V ⇔ 5.0 V |
|
TC74LCXR164245 |
2.3 to 3.6 V |
4.5 to 5.5 V |
VCCB side |
±12 mA |
Up to 74 MHz |
Series resistor for noise reduction |
2.5/3.3 V ⇔ 5.0 V |
|
TC74VCX163245 |
2.3 to 3.6 V |
1.65 to 3.6 V |
VCCB side |
±24 mA |
Up to 70 MHz |
- |
1.8/2.5 V ⇔ 3.3 V |
|
TC74VCX164245 |
1.65 to 2.7 V |
2.3 to 3.6 V |
VCCB side |
±24 mA |
Up to 70 MHz |
- |
2.5 V, 3.3 V ⇔ 5.0 V |
|
Level Shifters |
TC7MP3125FK |
1.1 to 2.7 V |
1.65 to 3.6 V |
VCCA side |
±12 mA |
Up to 56 MHz |
Low-current-consumption circuit |
1.2/1.5/1.8 V ⇔ 2.5/3.3 V 1.2/1.5V ⇔ 1.8 V |
TC7MPN3125FK |
1.1 to 2.7 V |
1.65 to 3.6 V |
VCCA side |
±3 mA |
Up to 34 MHz |
Low current consumption |
1.2/1.5/1.8 V ⇔ 2.5/3.3 V 1.2/1.5 V ⇔ 1.8 V |
|
There are two kinds of dual power type supply bidirectional level shifters. The first is the dual power supply buffer type level shifter. It requires dual power supplies, but it is a three-state buffer type product with a built-in level conversion circuit. By setting the DIR pin to low or high, the input / output direction switches between A to B and B to A.
It can be used in a frequency band up to several MHz with a 1-MΩ pull-up resistor.
Bidirectional up/down translation (dual-supply level shift bus switches)
- Level-shifting via an external pull-up resistor
- No need to control the signal direction (DIR)
- Ideal for data lines whose direction changes automatically such as I2C BUS communication
- Rise time affected by pull-up resistors (i.e., possible frequency range dependent on the pull-up resistance value)
- Usable at frequencies of up to several MHz with a 1-MΩ pull-up resistor
Dual-supply level shift bus switches
Series |
Switch Type |
Supply Voltage |
Supply Voltage |
Control Pin |
On-Resistance |
Level-Shifting Examples |
|
|---|---|---|---|---|---|---|---|
Dual-Supply Level-Shifting Bus Switches |
TC7SPB9306TU (1bit) |
SPST |
1.65 to 5.0 V |
2.3 to 5.5 V |
Active-High |
11 Ω (max) |
3.3 V ⇔ 5.0 V |
TC7SPB9307TU (1bit) |
SPST |
1.65 to 5.0 V |
2.3 to 5.5 V |
Active-Low |
11 Ω (max) |
||
TC7WPB9306FK (2bit) |
SPST |
1.65 to 5.0 V |
2.3 to 5.5 V |
Active-High |
11 Ω (max) |
||
TC7WPB9307FK (2bit) |
SPST |
1.65 to 5.0 V |
2.3 to 5.5 V |
Active-Low |
11 Ω (max) |
||
TC7QPB9306FK |
SPST |
1.65 to 5.0 V |
2.3 to 5.5 V |
Active-High |
11 Ω (max) |
||
TC7QPB9307FK |
SPST |
1.65 to 5.0 V |
2.3 to 5.5 V |
Active-Low |
11 Ω (max) |
||
TC7MPB9307FK |
SPST |
1.65 to 5.0 V |
2.3 to 5.5 V |
Active-Low |
11 Ω (max) |
||
TC7MPB9326FK |
SPDT |
1.65 to 5.0 V |
2.3 to 5.5 V |
Active-High |
11 Ω (max) |
||
TC7MPB9327FK |
SPDT |
1.65 to 5.0 V |
2.3 to 5.5 V |
Active-Low |
11 Ω (max) |
||
The second kind of dual power type bidirectional level shifter is a dual power level shift bus switch.
It converts the power level using an external pull-up resistor with no need to control the signal direction.
Therefore, it is suitable for data lines that automatically switch direction, such as I2C BUS communication.
Since the output rise time is affected by the pull-up resistor, the supported frequency changes depending on the resistance value. When the pull-up resistor is 1MΩ, it can be used up to the frequency band of several MHz.