Improving “micro DC/DC” converter performance
A growing range of applications employ “micro DC/DC converters”, which help shorten product development time, such as time required for power circuit design and operation testing. These include not only wearable devices and wireless devices where there is a strong need for size reduction, but also industrial equipment and communication infrastructure which require high reliability.
In response to this widening range of applications, Torex has released the XCL220 series and XCL222 series, which extend the operating temperature range to Ta = 105°C. In addition, new control technology (Hisat-COT) realizes a fast transient response, and the output current is increased by reducing the ON resistance of the internal transistor. The XCL220 series and XCL222 series are pin-compatible with the XCL202 series and XCL206 series, our first phase of “micro DC/DC converters”, and this eliminates the need for printed circuit board layout changes, making these products easy to use.
1.Product specifications
1-1 Comparison of XCL202 and XCL222 specifications
| XCL202 | XCL222 | |
|---|---|---|
| Oscillation Frequency | 1.2MHz | |
| Control Method | PWM/PFM Automatic | Hi-sat COT PWM/PFM Automatic |
| Input Voltage Range | 2.0V ～ 6.0V | 2.5V ～ 5.5V |
| Output Current | 400mA | 500mA |
| Output Voltage Range | 0.8V ～ 4.0V | 0.8V ～ 3.6V |
| Operating Ambient Temperature | -40℃ ～ +85℃ | -40℃ ～ +105℃ |
| Lx SW "H" ON Resistance | 0.35Ω | 0.24Ω |
| Lx SW "L" ON Resistance | 0.45Ω | 0.16Ω |
1-2 Comparison of XCL206 and XCL220 specifications
| XCL206 | XCL220 | |
|---|---|---|
| Oscillation Frequency | 3.0MHz | |
| Control Method | PWM/PFM Automatic | Hi-sat COT PWM/PFM Automatic |
| Input Voltage Range | 2.0V ～ 6.0V | 2.5V ～ 5.5V |
| Output Current | 600mA | 1000mA |
| Output Voltage Range | 0.8V ～ 4.0V | 0.8V ～ 3.6V |
| Operating Ambient Temperature | -40℃ ～ +85℃ | -40℃ ～ +105℃ |
| Lx SW "H" ON Resistance | 0.35Ω | 0.24Ω |
| Lx SW "L" ON Resistance | 0.45Ω | 0.16Ω |
2.Conversion efficiency
2-1 Comparison of XCL202 and XCL222 efficiency
| IOUT | XCL202 | XCL222 |
|---|---|---|
| 0.1mA | 68.3% | 71.7% |
| 1mA | 84.9% | 87.8% |
| 10mA | 86.8% | 89.8% |
| 100mA | 87.8% | 91.5% |
| 200mA | 85.8% | 90.9% |
| 300mA | 82.5% | 88.6% |
| 400mA | 78.9% | 85.8% |
| 500mA | - | 83.5% |
Conditions:VIN=3.6V, VOUT=1.8V
Compared to the XCL202 series, the XCL222 series achieves high efficiency from light loads to heavy loads. By reducing the ON resistance of the internal transistor, self-heating is suppressed and efficiency is significantly improved at IOUT = 50mA and higher, enabling a higher output current.
2-2 Comparison of XCL206 and XCL220 efficiency
| IOUT | XCL206 | XCL220 |
|---|---|---|
| 0.1mA | 59.2% | 63.8% |
| 1mA | 82.2% | 85.1% |
| 10mA | 85.5% | 88.2% |
| 100mA | 86.1% | 88.6% |
| 200mA | 84.4% | 90.0% |
| 300mA | 82.2% | 89.1% |
| 600mA | 74.3% | 85.5% |
| 1000mA | - | 77.6% |
Conditions:VIN=3.6V, VOUT=1.8V
Compared to the XCL206 series, the XCL220 series achieves high efficiency from light loads to heavy loads. The coil inductance has been changed to 1.0μH to hold down dissipation due to DCR (equivalent series resistance) and other factors, and by reducing the ON resistance of the internal transistor, self-heating is suppressed and efficiency is significantly improved at IOUT = 100mA and higher, enabling a higher output current.
3.Load transient response
3-1 Comparison of load transient response of XCL202B181CR-G and XCL222B181ER-G
Conditions:VIN=5.0V, VOUT=1.8V, IOUT=0.1mA⇔300mA
1)XCL202B181ER-G, CIN=4.7μF, CL=10μF
2)XCL222B181ER-G, CIN=4.7μF, CL=10μF
It can be seen from the VOUT waveform that the XCL222 series has a fast load transient response by means of Hisat-COT control.