Using in-system programmable devices to implement power management and monitoring

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Using in-system programmable devices to implement power management and monitoring [Copy link]

The in-system programmable power management chip (ispPAC Power Manager) is the industry's first mixed-signal programmable logic device (PLD). It contains in-system programmable analog and logic blocks that can provide optimized power management functions, which is very useful for electronic systems that require multiple power supplies. The device integrates programmable logic, voltage comparators, reference voltages, and high-voltage field-effect transistor drivers, and supports single-chip programmable power sequencing and monitoring. Currently, Lattice has launched two in-system programmable power management chips, Power1208 and Power604.

Many advanced integrated circuits such as microprocessors, DSPs, FPGAs, and application-specific integrated circuits (ASICs) use multiple power supply voltages to optimize performance while reducing power consumption. However, users must add these power supply voltages to the device and power them on and off in a predetermined order to prevent damage to the device. As the first device in the in-system programmable power management chip series, Power1208 uses the advanced technology of Lattice's ispMACH CPLD and ispPAC programmable analog devices, and can flexibly, economically, and conveniently solve the above problems with only a single chip. The core of the device is the ispMACH PLD, which features 12 precision analog threshold comparators with on-chip reference voltages for power monitoring. Four noise-free digital inputs and four open-drain digital outputs can be used as system control interfaces. Four programmable high-voltage field-effect transistor drivers are used to control the power supply, and four programmable timers with 250KHz oscillators inside the chip are used to control delays. The device has been processed to work properly in a noisy power supply environment of 2.25 to 5.5 volts.

Figure 1 Power1208 internal structure (omitted)

Today's most advanced integrated circuits require the control of multiple power supply voltages, and this complex task is a major burden for system designers. The single-chip programmable solution provided by the Power1208 device brings unprecedented convenience to power management of various circuit boards and expands an important and unexplored field for the application of programmable devices. To develop this chip, you need to use development software. PAC-Designer software allows users to easily implement circuit design functions.

The

Power1208 can be used as a power sequencer and monitor. It can manage 8 power supplies and monitor 12 analog inputs. The device contains digital programmable devices that users can use to implement digital logic functions. The internal PLD is connected to 4 programmable timers, dedicated I/Os, and programmable monitoring circuit blocks. The internal PLD and timers can use the internal programmable clock oscillator or an external clock. The internal structure of the device is shown in Figure 1.

There are 12 independent comparators in the voltage monitor, each of which can set 192 trip points. The monitoring level is 1.2V, 1.5V, 1.8V, 2.5V, 3.3V or 5V. The output pins are configured in two modes. The 8 outputs are used to control 8 different power supplies. Pins OUT5-OUT8 are open drain outputs for interfacing with other circuits. Pins HVOUT1-HVOUT4 can be independently programmed as open drain outputs or field effect transistor drivers. When used as field effect transistor drivers, these pins are used to drive external N-channel MOSFETs to control the voltage on the circuit board. The four HVOUT drivers can perform programmable current and voltage control.

Figure 2 The voltage monitoring circuit inside the device (omitted)
Figure 3 Circuit control system (omitted)

Application of power supply monitoring

From Figure 1, we can see that VMON1-VMON12 are the monitored voltage input terminals. Figure 2 is a simplified representation of the power supply monitoring circuit inside the device. Each monitoring circuit consists of three parts: programmable voltage divider, voltage comparator, and programmable reference source. The core of the monitoring circuit is a voltage comparator. When the positive terminal voltage of the comparator is higher than the negative terminal voltage, the comparator outputs a high level; when the positive terminal voltage of the comparator is lower than the negative terminal voltage, the comparator outputs a low level. There is a programmable resistor divider in the circuit to preliminarily set the trip point of the comparator, such as 1.8V, 2.5V and 3.3V. The negative terminal of the comparator is connected to the internal programmable reference source. It can be set to 16 different values. Each can be adjusted with an accuracy of 1% for precise adjustment of the breakpoint of the voltage monitor.

Application of power control system

Figure 3 shows a power control system in which POWER1208 monitors the +5V input voltage, controls the power-on sequence of several voltages, and interfaces with the logic signals on the circuit board through the system reset SYSRESET pin and the power cut-off SHUTDOWN pin. In this system, there are three voltages, the +5V voltage is directly added to the circuit board, and the independent 3.3V and 2.5V voltages are provided by two voltage regulators. The system requires that the three groups of voltages are not powered on at the same time, but are powered on in sequence according to a certain timing. After waiting for a few milliseconds after one voltage is powered on, the other voltage is powered on. The order is 3.3V powered on first, then 2.5V, and finally 5V. In addition, it is required that the system reset signal SYSRESET always remains at a low level before all voltages are activated. After all voltages are activated, SYSRESET is at a high level. When SHUTDOWN is at a high level, all power supplies are turned off. The order is opposite to the order when powering on, that is, the 5V voltage is turned off first, then the 2.5V, and finally the 3.3V.

In this system, V5IN_OK is used as the input signal, and POWER1208 monitors the +5V signal. V5_EN, V33_EN, and V25_EN are the output signals of POWER1208, which are used to control the three field effect transistors to achieve the timing of controlling power on and power off. When designing this power control system, you can use PAC-Designer v2.0 software to implement the design of power supply sequencing and monitoring on the Power1208 device. PAC-Designer is an intuitive schematic input and simulation tool. Its latest LogiBuilder tool provides a series of easy-to-use drop-down menus to help users easily design complex sequencing and monitoring functions. First, define the input and output signals. Then write the following program according to the timing of power on and power off and input it into PAC-Designer.

Step0 Begin Startup Sequence
Step1 Wait for V5IN_OK
Step2 V33_EN =1,
Step3 Wait for 8.192ms using timer 1
Step4 V_25EN =1,
Step5 Wait for 8.192ms using timer 1
Step6 V5_EN = 1,
Step7 SYSRESET = 1,
Step8 Wait for SHUTDOWN
Step9 V5_EN = 0,
Step10 Wait for 8.192ms using timer 1
Step11 V_25EN =0,
Step12 Wait for 8.192ms using timer 1
Step13 V33_EN =0,
Step14 Begin Shutdown Sequence
Step 15 Halt

Finally, use the ispDOWNLOAD download cable to connect the device to the parallel port of the PC, and you can download the design completed in PAC-Designer to the device. The unique structural function of the Power1208 device makes it particularly suitable for controlling multiple power supplies. It can be widely used in a variety of electronic devices, including communication and network systems, storage systems, servers, test equipment, and automotive electronic devices. The device can also be used with N-channel switching field effect transistors and low-dropout output (LDO) regulators to provide a compact power control solution. Traditional solutions require the use of multiple analog and digital integrated circuits and many resistors and capacitors. Replacing traditional solutions with Power1208 not only saves costs, but also improves system reliability and flexibility.

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