TPS60101 Power supply solution for low power systems

    Abstract: This article introduces the performance characteristics and usage of a novel charge pump DC voltage regulator chip TPS60101, and analyzes its application in low-power microcontroller systems with examples.

    Keywords: TPS60101 charge pump low power microcontroller

With the development of microcontroller application technology, various application scenarios have more stringent requirements for microcontroller systems. Portable solutions have begun to occupy an increasing proportion in system design, and are increasingly tending to low-voltage, low-power Power consumption, miniaturization design. In these designs, nickel metal hydride, nickel cadmium or lithium batteries are generally used as the system power supply method; in some systems using AC power supply, backup battery power supply methods are designed. TPS60101 has outstanding advantages such as high efficiency, wide input voltage range, good voltage stabilization effect, low leakage current, and small size, and can provide a perfect power supply solution for these designs.

1 Introduction to TPS60101 chip

　　TPS60101 is a low-noise charge pump DC voltage regulator chip newly launched by Texas Instruments. It can provide stable DC power supply for microcontroller systems when the input voltage dynamic range is large.

1.1 Package form and pin description

　　The TPS60101 chip is packaged in a special TSSOP chip package, as shown in Figure 1.

The function description of each pin of the chip is listed in Table 1.

Table 1 TPS60101 pin functions

1.2 Performance characteristics of TPS60101

　　Precision manufacturing process and excellent design make TPS60101 have excellent electrical performance:

◇ The maximum output current is 100 mA, which can meet the requirements of most low-power microcontroller systems;

◇ Less than 5 mV output voltage fluctuation, providing a regulated output of 3.3 (1±0.04) V;

◇ Only a few peripheral components are needed, no resonant coils and other devices are needed, and the application circuit is very small;

◇ Charge pump efficiency can reach 90%;

◇ Wide input voltage range, 1.8~3.6 V can work normally, fully ensuring that the microcontroller system receives a stable power supply during different types of external power supplies and changes in battery power status;

◇ 50 μA working additional current and 0.05 μA shutdown leakage current, consuming very little power;

◇ In shutdown mode, the output of the regulated power supply is isolated to increase the reliability of power management;

◇ Miniature TSSOP chip packaging, reducing the size of the application circuit. This packaging form integrates a heat sink at the bottom of the chip and can be directly connected to the printed board, effectively improving heat dissipation performance without increasing the circuit volume.

2 How to use TPS60101

　　Compared with general power supply voltage stabilizing chips, the use of TPS60101 has some particularities and noteworthy points. The author will elaborate on it based on the actual use experience.

2.1 Selection of charge pump working mode

　　TPS60101 integrates two buck-boost charge pumps on the chip. By changing the external level of the chip's 18-pin COM, the two working states of the charge pump can be selected: COM is connected to ground for push-pull mode, and connected to high level for single-ended mode. In the push-pull mode, the working status of the two charge pumps on the chip has a phase difference of 180° in the time domain, and each occupies 50% of the load cycle for push-pull output. This method can avoid output voltage fluctuations to the greatest extent and obtain the best voltage stabilization effect, but it requires four external electrolytic capacitors. In single-ended mode, the two charge pumps are parallel outputs with no phase difference. This method requires only 1 external capacitor. Figure 2 shows the application circuit for single-ended mode.

　　Generally speaking, when there are no strict requirements on the size of the actual application circuit, the push-pull mode should be selected to obtain the best working performance. However, since the TPS60101 chip itself is very small, the main factor affecting the size of the application circuit is the external components. If operating in single-ended mode, the size of the application circuit can be reduced by more than half. If the voltage stability requirements are average but the circuit volume is strict, you can also consider using the single-ended mode.

2.2 Synchronization clock source selection

　　The synchronous clock source of TPS60101 can be selected by changing the external level of SYNC on pin 2. SYNC is connected to a low level to use the synchronous clock signal generated by the on-chip crystal oscillator, SYNC is connected to a high level to use an external synchronous clock signal, and the external clock signal is led to the 3V8 pin.

　　In general, you only need to use the on-chip clock. However, if the power supply system of TPS60101 works at a certain fixed frequency, it is more reasonable to use external clock synchronization. It should be noted that when using external clock synchronization, the SKIP pin should be connected to ground to reduce output noise. Figure 3 shows the application circuit of the external synchronous clock method.

    2.3 Selection of output working mode

　　The output working mode of the chip can be selected by changing the external level of pin 19 of the chip 3V8. Connect 3V8 to low level for standard 3.3 V output, and connect to high level for preset 3.8 V output. In general applications, the first method should be used; only when the voltage requirements are very strict, the second method should be adopted. TPS60101 provides a rough 3.8 V output, and the subsequent stage is connected to an external low-dropout voltage regulator, such as the TPS7330 chip, to obtain a more precise 3.3 V output.

2.4 Circuit printed board design

　　There are some things worth noting about the circuit board design of TPS60101:

First, the chip pin width is 0.30 mm and the pitch is 0.65 mm, which is denser than ordinary SO patch packaging and requires self-built packaging library files;

Second, a heat sink is integrated at the contact point between the bottom of the chip and the printed board. The corresponding position on the printed board needs to be laid with copper and soldered, and connected to the power ground;

Third, all PGND and GND pins should be connected with thick and short wires as possible.

3 Application of TPS60101 in low-power microcontroller system

　　In the process of designing and implementing a low-power microcontroller system, we used the TPS60101 chip as the system power supply solution and received satisfactory results.

　　This system is a mobile wireless data collection device that supports USB bus communication. The system uses the 8051 core microcontroller as the central controller and expands the wireless data acquisition module, Compact Flash card data storage module and USB bus transceiver module. The system strictly requires low power consumption and mobility, so the system is powered by lithium batteries. Because the system does not have strict requirements on circuit volume, the main components work in asynchronous mode, and the nominal output voltage of 3.3 (1±0.04) V can meet the needs, so in the actual design, the charge pump is set to push-pull mode, and the chip Use on-chip synchronous clock and output in standard 3.3 V mode. The application circuit is shown in Figure 4. Figure 5 is a schematic diagram of the system power supply mode.

　　In order to further reduce system power consumption, the system is powered by the USB bus when performing USB data communication. The system uses a discrimination circuit to determine whether it is currently connected to the USB bus, and then selects the power supply method based on the result. In addition, an automatic sleep function is designed to reduce unnecessary battery consumption. The system uses two TPS60101 power supply methods, one is used to provide uninterrupted power supply to the microcontroller system, and the other is used to power the other modules. When the system does not receive external input for a period of time, the microcontroller controls the ENABLE of TPS60101 to turn off the power of other modules in the system; when the system receives external input, it returns to the working state from the sleep state. The C51 program segment that implements the scheduled sleep function is as follows:

while(1) //Program main loop

{ …… //Enter sleep state if the idle time is greater than 5 minutes

　　if ((idletime>3000)&&(sysmode==ON)

　　　　{idletime=0;enable=0;

　　　　　　sysmode=SLEEP;}

　　if (IsInput==TURE) //Wake up if there is input

　　　　{enable=1;sysmode=ON;}

…

}

void timer0() interrupt 1 using 1

{ //Interrupt interval is 100ms

　　…

　　if (sysmode==ON)

　　idletime++;

　　…

}