General description

LM2984C positive voltage regulator has three independent tracking outputs, which can provide memory circuit, peripheral sensor and spare power at the typical microprocessor system. LM2984C includes monitoring circuit output of its own high current and an external MP. If any error conditions will be set and keep the reset error logo until the failure is terminated. Because these functions are included in a typical microprocessor system in the same component as three regulators. LM2984C also has a low voltage difference (the rated output current is 0.6V) each with three regulators. In addition, in the standby mode, the static current can be reduced to 1MA. LM2984C and all regulatory circuits are protected, preventing the battery from reverse installation or 2 batteries. Familiar regulator functions such as short circuit and heat overload protection are also provided. Provide 5V fixed output in PLAS TIC TO-220 power package.

Features

Three low -voltage difference tracking regulators

output current exceeds 500 mAh

Static low -current backbone stabilizer

] Micro -processor fault reset sign

Powering delay reset

Expert pre -micro -adjustment 5V output

Anti -battery protection

overvoltage protection

Reverse transient protection

Short -circuit protection

Internal heat overload protection

large current output y opening/customs switch

100%heat thermal heat Extreme electric aging

Cout must be stable for at least 10 mf. It may increase without having to maintain supervision during the transient. As far as possible, the regulator may be approached. The regulator must be adjusted within the rated work temperature range. The equivalent series resistance (ESR) of the capacitor is critical; see the curve.

Absolute maximum rated value

Input voltage

Survival voltage (K100 ms) 35V

Working voltage 26V

Internal Power consumption internal limited

Work temperature range (TA) 0 ° C to A125 ° C

The highest knot temperature (Note 1) 150 ° C

Storage temperature range B65 ° B65 ° C to A150 ° C

Lead temperature (welding, 10 seconds) 230 degrees Celsius

shall determine the ESD rated value.

Electrical features

VIN E 14V, output E 5 ma, COUT E 10 mf, TJ 25 ° C (Note 6), unless there is another instructions

Electric characteristics (continued)

VIN E 14V, output E 5 ma, output E 5 ma ，Ibuf e 5 mA，Istby e 5 mA，Rt e 130k，Ct e 0.33 mF，Cmon e 0.47 mF，Tj e 25§C（注6），除非

另有规定的

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Note 1: The thermal resistance between the connector without a radiator is 3 ° C/W. The thermal resistance of the shell to the environment is 40 ° C/W.

Note 2: Guarantee test limit, 100%production test.

Note 3: In order to ensure the design limit (but not 100%production test) within the specified temperature and power supply voltage range. These restrictions are not suitable for calculating the quality of shipments.

Note 4: When the main themeter output (VOUT) drops below 4.0V or rises to 5.5V, the internal comparator is tested. If any situation in the output, the reset error logo is kept at a low position until the error condition is terminated. After the delay of RT and CT settings, the reset error sign will become higher again. (See the application part.)

Note 5: This parameter is used to measure how short pulses can be detected at the MP monitor input terminal. This parameter is mainly affected by the CMON value. (See typical performance characteristics and application parts.)

Note 6: In order to ensure that the knot temperature is constant, a low -occupying ratio pulse test is used.

典型性能特征

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Program prompt

Output capacitor

LM2984C output capacitor needs stability. Without them, the regulator output sometimes oscillates a lot of volts. Although the 10 millivolo is the minimum recommended value, actual size and type may vary from the application load and temperature range. Effective series resistors (ESR) of capacitors can also affect IC stability. Due to the different ESRs of different brands, in order to determine the minimum capacitance value used in production, some tablets may be needed. The worst case is the maximum load that is usually measured at the lowest environmental temperature and expected. The size of the output capacitor can add value as required than the minimum value. A possible purpose is to maintain the output voltage under the short -term conditions of negative input transient, which may be the characteristics of a specific system. Capacitors must also be available in the rated system at all environmental temperatures. A variety of aluminum electrolytic grooves will be lowFrozen at the temperature of B30 ° C, thereby reducing effective capacitors to zero. Keep the stability of the regulator below B40 ° C, and the rated value of the capacitor at this temperature (such as 钽 must be used). Each output must be connected by the capacitor, even if the capacitor is not used.

Spare output

Spare output is used to need a spare storage circuit. The output of the large current regulator is controlled by the ON/OFF pin described later. Under all conditions, as long as the IC provides sufficient input voltage. Therefore, the memory supply and other circuits from the output power supply are not affected by the transient and heat shutdown of the positive line. The design of the spare regulator circuit makes the output of another regulator off. The capacitor at the output of this regulator can be increased without restrictions. This will help keep the voltage during the output negative input transient period also help reduce the noise of all three outputs. Because another dual -track spare output: therefore, any noise is reduced, which will also reduce the other two noise voltage.

Caps output

The buffer output is designed to drive the peripheral sensor circuit in the MP system. It will track the reserve and the main knot device within a few hays at normal operation. Therefore, the peripheral sensor can cut off this power and has the same working voltage as the MP system. This is important if the use ratio sensor system. When the other two buffer outputs short circuit, the output is in normal working state. When the sensor wires are cut off, this can protect the MP system that is temporarily short -circuited by the power interruption, that is, the sensor signal only when the MP and memory circuit will continue to operate.

The output of the buffer is similar to the main output, because it is controlled by the ON/OFF switch for the standby mode. It is also a fault protection device that prevent overvoltage and heat overload. If the voltage is about 30V (such as load reserves) higher than input, this output will be automatically closed. This can protect internal circuits and make ICs be expected. Because this output is the power consumption in the integrated circuit. The main output of the main output is designed to supply a relatively large load, i, E. about 500 mAh. As a result, it is also protected from overload and heat overload. This output will track two other normal operations within a few slots. Therefore, it can be used as a voltage spare or buffer output of any signal generated by the reference circuit. This is an important sensor system in a proportional analysis or any system power supply voltage that needs to be accurately matched.

Open/customs switch

Open/switch to control the main transmission and buffer output. The threshold voltage is compatible with most logic and the lag of about 20 millivolves to ensure that the ""clean"" switching from the standby mode to the activity mode is the same. This pin can be a 10 -kX resistor by continuous power supply by the regulator.

Power off the super control

Another possible method is to use diode connecting/disconnect signals and another signal to the main output in order to use itAfter a period of time, the power -on/off signal has been removed (see Figure 1). The connection/disconnection switch was initially pulled up through the diode D1. The main output will be connected and the D2 to the ON/OFF switch is powered by the diode to effectively lock the main output. The opening of the circuit collecting electrode chip Q1 is connected to the ON/OFF pin and the two diode, and the regulator is forced to close after a period of time determined by MP. In this way, MP can cover the power -off command and store it in the standby mode

Reboning output

This output is an open set of NPN crystal tube When the error conditions appear in the main output or when the MP error is detected (see the MP monitor section). If the main output voltage is lower than 4V or higher than 5.5V, the reset output is forced to a low level and remains at a low level at the low level at the low level and scanned by two external components RT and the computer fault. There is a slight lag in the two of the two that the threshold voltage drop at the rapid rise of the reset output meets the requirements of most MP requirements to reset the input.

Delayed reset

The resistance RT and the capacitor CT settings have been felt at a low level in the main output error. The delay from the following formulas: TDLY E 1.2 RTCT (seconds) When the main output is outside 4V to 5.5V windows, that is, during the power period, the delay will be reset, short -circuit, overvoltage, low voltage, heat shutdown, or power off. Therefore, as long as the output voltage exceeds the adjustment range, MP will reset. (It should be noted that only when the main output is wrong, the reset is started. This buffer and spare output do not directly monitor the error conditions.)

MP monitor reset

There are two different and independent independent ones Monitor the system in LM2984C. The above system monitor the main regulator output, and starts the delayed resection when the output is error. Another error surveillance system is MP watch dog. These two systems are low when the internal and compulsory resetting output is low. This look at the door dog circuit continues to monitor the MP with a positive pulse during normal operation. The cycle of this pulse is usually milliseconds, and the pulse width is usually 10 microseconds. If the pulse disappears, the dog circuit will take timeout, and the low reset will be sent to parliament members. The timeout time is determined by 2 to determine the external components, RT and CMON, according to the formula: TWINDOW E 0.82 RTCMON (second) the width of the reset pulse is set by CMON and internal resistors according to the following content: reset the PW E 2000 CMON (second) square wave signal The CMON input can be filtered in the following ways to monitor the error, so that the signal is detected. Figure 2 is the schematic diagram of A to distinguish the typical circuit of the input signal. The resistor RTC and capacitor CTC only generate a short positive pulse MP monitor input through the square wave. If the input signal is in high or low -state time, A will generate low reset.

The threshold voltage and input characteristics of the foot are compatible with almost all logical families.The width of the pulse is detected by the door dog circuit.This is because the output is detected at a high state at the input terminal.The minimum detection pulse width can be determined by the following formula: PWmin E 20 CMON (second)