Features

Wide power supply voltage range: 6.0 V to 30.0 V; multiple inputs can monitor 3 to 6 battery voltage and 2 temperatures; adjustable threshold levels: overvoltage, underold pressure, ultra -temperature ultra -temperature ; Alarm options: separate or shared alarm; extended temperature range performance; -40 ° C ≤ TA ≤+105 ° C; chrysanthemum chain; internal reference; power supply by battery pack; LDO can be used for power isolation device; suitable for automotive applications; suitable for car applications; Extensive self -inspection functions help meet ASIL/SIL requirements.

Application

Lithium -ion battery backup monitoring and threshold detection; electric and hybrid vehicles; industrial vehicles; uninterrupted power supply; wind energy and solar energy.

General description

AD8280 is a hardware safety monitor that is only used for lithium ion battery packs. The device has monitoring inputs of 6 batteries and 2 temperature sensors (NTC or PTC thermistor). The device is designed to connect the chrysanthemum chain with the additional AD8280 device to monitor a stack that is significantly more than six units without a large number of isolations. The output can be configured to be independent or shared the alarm state.

AD8280 is independent of the main monitor work, including a reference and LDO. Both of them are fully powered by the battery pack. The reference, together with the external resistance distributor, establishes a trip point for overvoltage and owed voltage. Each unit channel contains a programmable dehydration circuit to prevent alarm from instantaneous input levels.

AD8280 also has two digital pipes, and you can choose a variety of input combinations in the community to be monitored. The most important thing is that it has a self -inspection function to make it suitable for high -reliability applications, such as car hybrid electric vehicles or higher voltage industrial applications, such as uninterrupted power supply. AD8280 can work within the temperature range of -40 ° C to+105 ° C.

Function box diagram

Typical performance features

Operation theory

Figure 44 shows the frame diagram of AD8280. AD8280 is a threshold monitor that can monitor up to six battery voltage and two temperature voltage. The device can also be used for chrysanthemum chain configuration to monitor as many cell needs as possible. The advantage of the chrysanthemum chain configuration is that it only needs to isolate the alarm signal on the bottom of the chain to keep the alarm signal away from the high -pressure environment, thereby reducing system costs and minimizing the required board space.

The battery and temperature voltage input uses VIN0 to vin6 input and VT1 and VT2 input to the device. becauseThe six -unit stack voltage can be as high as 30V, the input voltage is moved horizontally, and the minimum potential (device ground or VBOTX) of the AD8280 is referred to. Then compare these voltage input window comparators and compare it with the sliding point set by the external resistance distributor.

If the battery or temperature voltage input exceeds or lower than the selected trigger point, the alarm in the form of digital voltage level will change the state of the device voltage output (AVOUTXX). When multiple devices are used in the chrysanthemum chain configuration, the alarm status also exists in the form of current output (AIOUTXX), which communicates with other devices.

This device contains a programmable dehydration circuit to ensure that the transient voltage appears at the battery input terminal.

The device also contains a LDO and reference. LDO can drive external components, such as thermal resistance or isolation, and the benchmark can be used to determine the trip point with the sterilizer.

AD8280 has the following unique functions and functions:

can monitor three, four, five, or six units.

negative or positive temperature coefficient thermistor can be used.

You can configure multiple devices in the chrysanthemum chain to monitor hundreds of units. Information on the status of the entire chrysanthemum chain, and the input signal that enables the device and start self -inspection, all communicate through the bottom or main device in the chain.

alarm output of overvoltage, under pressure, and ultra -temperature state can be shared. Each output indicates the same state of the alarm conditions that occurs, or the alarm output can be used as a separate entity. Each entity can be used as a separate entity. Each entity Indicate a state of specific conditions.

Wide self -test function to ensure that the internal components work is normal. Self -inspection is required to start the pin.

Application information

Typical connection

Figure 45 is a box diagram of the typical connection of AD8280.

Unit input

Six battery packs must be connected to Vin0 to VIN6, the maximum potential is connected to VIN6, and the minimum potential is connected to Vin0. As shown in Figure 45, a low -pass filter consisting of a 10 -kΩ resistor and 10 NF capacitors is connected. The minimum potential in the six -unit stack must also be connected to VBOT1, VBOT1S, VBOT2, and VBOT2S, and the maximum potential must be connected to VTOP and VTOPS through diode. It is recommended to use 0.1 μF and 10 μF decouple capacitors at the foot of the VTOP tube.

Selection of temperature input and thermistor selection

VT1 and VT2 are voltage input. The designed thermistor used to configure the resistance distributor as the resistance allocation device, as shown in Figure 45. The voltage at the top of the heating resistor division must beLDO's +5 V output. The LDO foot can provide more current than the REF tube foot, and it is more suitable for driving the thermistor resistor division.

If the voltage source other than the AD8280 LDO drives the thermistor resistor (V), when the AD8280 is disabled or powered off, the VT1 and VT2 voltage must be adjusted to 0 V, because when the LDO is also 0 is also 0 also at 0 When V, VT1 and VT2 input must be 0 V.

In addition, if the resistor (R) used at the top of the thermistor resistance bridge circuit is less than 10 kΩ, another resistor must (R) (see Figure 46). The two resistors must be greater than 10 kΩ (R+R GT; top at the top of 10,000 euros). Only when V is not AD8280 LDO, this configuration is needed.

This device can work at the same time as negative temperature coefficient (NTC) and positive temperature coefficient (PTC) thermistor. For NTC, the NPTC pin must be connected to the logic (VBOTX foot); for PTC, the NPTC pin must be connected to the logic high (LDO tube foot). If the device is set to NTC mode, when the voltage at VT1 and VT2 drops below the trigger point, the OT alert will be triggered. If the device is set to the PTC mode, when the voltage at the VT1 and VT2 is higher than the trigger point, the OT alarm will jump.

The number of cells selected

The device can be configured to use three, four, five or six units. Table 5 describes how to program the SEL0 and SEL1 pin to determine the number of units to be monitored. Ligram low indicates VBOTX, logical high represents LDO output voltage. Figure 47 to Figure 49 shows how to connect the unit to the device in the five -unit, four -unit or three -unit application.

threshold input

threshold (or trigger point) to set an external pressure division to provide the maximum flexible flexibility sex. The required checkpoint voltage is connected to the following pins: OV (overvoltage trip point), UV (owed voltage checkpoint), and OT (overheating card tags). The +5 V output of the reference (REF) or LDO can be used as the highest voltage of the compressor. However, because the benchmark output is more accurate than the LDO output, the benchmark output is more suitable for setting the distributor to power the distribution point. If the thermistorizer used for the temperature sensor is driven by the LDO output, it is recommended that the LDO driver OT checkpoint is recommended to obtain a better temperature drift performance.

The decoupled capacitor (0.1 μF) must be used with the bottom of each pressure device. In addition, 2.2 μF capacitors must be used on the reference output terminal, as shown in Figure 45.

The load resistance of the reference pin must not exceed 25kΩ. SoWhen using the REF driver's three signs (OV, UV, and OT), the resistance of each pressure device is recommended to be at least 75 kΩ. If only two reference drivers (OV and UVs) are used, the total power of each componter must not be less than 50 kΩ.

The name of the top and bottom device

When configured in the chrysanthemum chain, the AD8280 works according to its position in the chain: the top device (highest potential), intermediate device or bottom device at the top (Minimum potential). The position of the top and bot pipe foot specifies the location of each device in the chrysanthemum chain. Table 6 is a logical table for identifying the position of the device in the chrysanthemum chain. If it is not used in the chrysanthemum chain, it is identified as a single (independent) device.

The high logic and low logic of the top and bottom tube feet are different from other logical tube feet of AD8280. TOP and BOT tube feet are referenced by VTOP (high logic) and VBOTX (low logic).

1. For the top and bottom tube foot, logic 1 is VTOP, logic 0 is VBOTX.

The bottom device at the chrysanthemum chain configuration

The bottom equipment in the chrysanthemum chain configuration is the main device, which receives voltage input from the Enbi and TESTI tube foot. AIINOV, Ainuv, and AINOT's pins of the bottom devices are connected to AIOUTOV, AIOUTUV, and AIOUTOT tube feet of the next high potential device in the chrysanthemum chain, respectively. Aioutov, AIOUTUV, and AIOUTOT tube feet at the bottom device can keep floating or bind to device ground (VBOTX).

Intermediate devices in the structure of the chrysanthemum chain

When the AD8280 is specified as an intermediate device, AIINOV, AIINUV, AINOT, Enbo, and Testo are connected to AIOUTOV, AIOUTUV, and AD8280, respectively. AIOUTOT, Enbi and Testi.

The top device in the chrysanthemum chain configuration

When the AD8280 is specified as the top device, AIINOV, AIINUV, AINOT, Enbo, and Testo can keep floating or bind to VTOP.

Independent device

When the AD8280 is specified as a single device (used as an independent device), Aioutov, AIOUTUV, and AIOUTOT tube feet can keep floating or bind to device grounding (VBOTX). Aiinov, AINUV, AINOT, Enbo, and Testo pin can be kept floating or binded to VTOP. AD8280 accepts voltage input of Enbi and TEST pins.

Alarm signal of the chrysanthemum chain configuration

Regardless of the designWhat is the name? Alarm signals can be used as AVOUTOV, Avoutuv and AVOUTOT tube feet.

These signals indicate the status of the device of the monitoring voltage alert, as well as the status of the device high in the chrysanthemum chain. Use the isolation device to bring the signal out of the high -pressure battery environment.

Typical chrysanthemum chain connection

FIG. 50 shows the typical connection of the device in the chrysanthemum chain.

Sharing or separate alarm

AD8280 can be configured as three separate alarms or a shared alarm. Connecting AlRMSEL pins to 5 V logic high levels will force the device to enter a separate alarm mode. In this mode, each alarm is triggered by the specified monitoring function. In other words, the OV alarm can only be triggered only when there is an over -pressure condition at any unit input; the UV alarm can only be triggered when there is an underwriting condition at any unit input; At the time, the OT alarm will be triggered. In the shared alarm mode, any of the three cases of overwhelming, under pressure or overheating will trigger the alarm on all three signal chains. In the sharing mode, just monitor one alert, because these three alarms include the same signal.

Dalbility Options

The dehydration circuit is available, so the device is immune cell input transient. If the device input end is sufficient to trigger the high or low -level transient voltage of the alarm, if the transient voltage appears less than the selected deserture time, the alarm state will not occur.

DGT0, DGT1, and DGT2 tube feet are determined to take off time. Table 7 shows available options and the corresponding logic levels used when using DGT0, DGT1 and DGT2 tube feet.

Do not connect all three off -gum sales (DGT0, DGT1, and DGT2) to the logic high (111); this setting is only used in the factory testing equipment.

If necessary, set the dehydration time to 0.0 seconds (000), and allow an external dehydration circuit. In addition, when the dehydration time is set to 0.0 seconds, the time required for the equipment to complete the self -inspection is significantly reduced (see the self -inspection part). The DGTX pin must be connected to a fixed logic level, and it must not be switched or changed during the operation of the AD8280.

Enable and disable AD8280

AD8280 to disable or enter the standby mode, the method is to set the ENBI pin to the logic low level, and the static AD8280's static static The current has been reduced from a maximum 2.0 mAh to 1.0 Weire, and LDO and reference output are reduced to 0 volts. Set the ENBI pin as a logic high level to exit the device with the standby mode and enable.

When configured with AD8280 A chrysanthemum chainAt the time, the enable/disable signal is sent to the voltage logic level of the device specified as a device specifically at the bottom device (the bottom device monitor the minimum voltage unit). The bottom device transmits/disabled signals from the ENBO pin to the top, and enters the ENBI pin of the next higher device in the chrysanthemum chain. All the devices in the chrysanthemum chain are enabled by sending the logic of the ENBI pins of the bottom or the main device. By sending low logic to the ENBI pin of the bottom device, all the equipment in the chrysanthemum chain is disabled.

Alarm output

The alarm status of AD8280 is displayed as the voltage logic level of AVOUTOV, Avoutuv and Avoutot pin. When the AD8280 is in the chrysanthemum chain configuration, the alarm state is passed from the AIOUTXX pins of a device to the AIinxx pin of the lower low potential device in the chrysanthemum chain. Figure 51 shows the output status when the device is in the state of unprooping (low logic) or alarm (high logic) state.

If the AD8280 is configured to a shared alarm mode, the status of all three voltage output pins (AVOUTXX) is the same. In the shared alarm mode, the unused foot can keep floating, connect to the ground by high resistance to restrict current consumption, or connect together.

Self -test

AD8280 has a wide range of internal components to ensure its unique ability to ensure its normal work. This feature is very important for designers who meet the safety integrity level guidelines that meet the IEC 61508 or ISO 26262.

The device has internal fault conditions and compares the results with the expected results. During the self -inspection, the status of the alarm signal was interrupted, and the self -inspection pass/failed state through the alarmxx and AIOUTXX.

Since the AD8280 uses internal benchmarks to perform self -test, the self -test testing threshold pins are opened and short -circuited. Figure 51 is shown in Figure 51. For timing definition of self -inspection functions, see Figure 52.

To start a self -test, TEST pin will get a rising edge prompt from 5 V logic electric pulse (test pulse). The pulse applied on the testicles must maintain a high level (T minimum value) in the shortest time. After starting the pulse rising edge of the self -inspection, when the device performs internal self -inspection, the alarm status of any AVOUTXX or AIOUTXX pins enters the logic high state. After sufficient time to perform the test and assume that the device passes the self -inspection, the alarm status will be restored to an unbalanced state (low logic). If the equipment self -examination fails, the alarm remains in a high state when the decrease of the test pulse appropriate during testing occurs.

The smallest T depends on the state of the DGTX tube. If all three DGTX tubes are connected to the logic low level, the self -inspection will ignore the deserture function of the device and complete it in a short time (up to 25 milliseconds)Self -inspection. At least one DGTX pin is set to a logic high -electricity, the AD8280 defaults to the minimum deserture time of 80 ms during self -inspection. Because self -test includes multi -layer and passed, the shortest waiting time before the self -test is 1000 milliseconds. Therefore, if you need to self -test faster, set the internal deserture time to 0.0 seconds. If you need to remove gel, please use an external dehydration circuit.

Self -test of the chrysanthemum chain structure

When configured multiple AD8280 devices in the chrysanthemum chain, self -examination can also be used. The test pulse is used as a test selling for the voltage to apply to the bottom device, and then moves up along the chain as the current. Once the device sees the rising edge of the test pulse, starts the self -test of each device almost at the same time. When the highest device in the chain passes the self -inspection, it sends the information to the next lower device in the chrysanthemum chain. Even if the device completes self -inspection, it cannot pass the result to the next device in the chrysanthemum chain until it receives the signal from the device above it. This process continues, and each device drops the chain. Therefore, when the device at the bottom of the chrysanthemum chain passes through the signal, it indicates that each device in the chrysanthemum chain has passed the self -inspection. If any device in the chain fails to pass the self -test, the device under the fault device has never received the signal, and then the bottom device has never received the signal. Therefore, regardless of whether the underlying device passes the self -inspection, the AVOUTXX signal of the underlying device will never change the high state of logic at the startup of self -inspection, and users know that there is a faulty device in the chain.

Self -inspection alarm conditions

If the alarm occurs before or after the self -inspection pulse is started, the alarm will lead to the failure of the self -inspection. The time span of this situation depends on the time -off time.

Desert time 0.0 seconds. If the alarm occurs within 20 ms before the self -test pulse anterior edge to the time period of the self -test pulse, the alarm occurs, the equipment cannot be self -test.

dehydration time gt; 0.0 seconds. If the alarm occurs within the time period of 100 ms before the self -test pulse anterior edge to the self -test pulse front edge, the equipment cannot be self -test.

Therefore, under the abnormal situation of the self -inspection of the equipment and the alarm state after self -inspection, it is recommended to re -test the equipment to ensure that the alarm will not occur before or after starting the self -inspection.

When the device is in a shared alarm mode or a separate alarm mode, self -examination work. When the device is in a separate alarm mode, the self -inspection status on the output is only related to the parts related to the monitoring state in the internal circuit: overvoltage, under pressure or overheating.

When the self -test and monitoring strategy monitor the self -inspection signal on the AD8280, pay attention to the following items:

, AVThe alarm on OUTXX sales remains effective within 2 μs after the test sales are rising.

When the testicular pulse rising edge appears, monitor the AVOUUTXX pin to ensure that it is in a high state after the minimum of T. Re -

After the maximum time of TST, verify whether the avoutxx pin has been changed to a low state, indicating that the device passes the self -inspection. At the same time, ensure that the minimum length of the testicular pulse is greater than the maximum value of TST. The self -examination status of AvoutXX pins is valid before TSTV reaches the maximum value after testing the pulse.

After the backing of the pulse, the alarm status is valid again.

Protective element and upper/lower resistors

As shown in Figure 45, some equipment is added to provide protection in a high -pressure environment. The Qina diode Z1 ensures that the voltage of the six battery packs will not significantly exceed the maximum 30V on the device. It is recommended to use 33 V rated Zina diode.

You can also use the diode in the chrysanthemum chain line (from high potential to low potential anode to cathode) to protect the equipment when the battery connection occurs, so as to generate high reverse voltage on the AD8280 Display these diodes). The diode must have a reverse voltage rated value comparable to the maximum voltage of the battery system.

If the diode is used in the chrysanthemum chain, it is also recommended to be between the top unit (anode) in the stack and the VTOP (cathode) of the top device and the VBOTX (anode) of each device The diode is used between the VTOP (Cathode) of the minimum potential device.

Since there is no pull -down or drop -down resistor inside the device, users may want to pull the test of the bottom device to VBOTX (device ground) through a 10 kΩ resistor. If the line is disconnected, the resistor can ensure that the device is not locked in the self -inspection mode. In addition, users may want to pull up the ENBI pin on the bottom of the chrysanthemum chain so that if the line is opened, the chain is kept in enable (power -on) mode.

Electromagnetic interference considerations

In order to increase the resistance to electromagnetic interference (EMI), the following components and layout schemes (see Figure 50).

22 PF capacitors on each chrysanthemum chain.

arrange the chrysanthemum chain on the internal PCB layer.

use ground planes above and below the chrysanthemum chain line (connected from high potential device to VBOTX) to block them.

wiring the connection from VBOTX to VTOP to ensure the low impedance connection between them.

use iron oxygen magnet beads on VTOP line, as shown in the figure50 shown.

100 NF capacitors in each battery pack in six battery packs.

Put the AD8280 device as closely as possible on the board as much as possible with the length of the chrysanthemum chain.

System accuracy calculation

When calculating the accuracy of the system, you need to consider four sources of error:

trigger point error (see Table 1)

[

[ 123] Reference voltage error (see Table 1)

resistance tolerance

resistance temperature coefficient

Sample calculation

The following is an example calculation of overvoltage accuracy. In this calculation, assuming the following conditions:

The resistor used to set the trip point in the external resistor division is ± 1%, 100 ppm/℃ resistor.

temperature range is -40 ° C to+85 ° C.

The required overvoltage point is 4.0 V (the selected resistance must be 15 kΩ and 60 kΩ).

This section will introduce the cause of the error.

The maximum trigger point error

The maximum trigger point error is ± 15 mv.

Maximum reference error

The maximum reference error is as follows: (60/(60 + 15)) × ± 50 mv ± 40 mv

maximum resistance capacity error [123 ]

The maximum resistance difference error depends on the resistance value. If one resistance is high and the other is low, the worst mistake is as follows:

(60.6/(60.6 + 14.85)) × 5.00 v 4.016 v (error of +16 mv)

] (59.4/(59.4 + 15.15)) × 5.00 v 3.984 v (error of 16 mv)

In this sample calculation, the maximum resistance error is ± 16mv.

Maximum temperature coefficient error

If one resistance drifts high and the other resistance drifting is low, the worst case is as follows:

60 kΩ+(100 ppm (100 ppm /° C × (25 ° C-(-40 ° C)) × 60 kΩ) 60.39 kΩ

15 kΩ- (100 ppm/℃ × (25 ℃-(-40 ℃) × 15 kΩ × 15 kΩ ) 14.9 kΩ (60.39/(60.39+14.90)) × 5.00 V 4.010 V PPM/° C × (25 ° C-(-40 ° C)) × 15 kΩ) 15.1 kΩ

(59.61/(59.61+15.10)) × 5.00 il 3.990 volts (error #87222222 ; 10 millivolves)

In this sample calculation, the maximum temperature coefficient error is ± 10mv.

The total accuracy of the system

The sum of the system accuracy or all errors is ± 81 MV. If the resistance pairing coefficient matchs and the drift direction is the same, the part of the error can be ignored. The total accuracy of the system is ± 71mv.

The size of the shape

] Automotive product

AD8280W model can be used to control manufacturing to support the quality and reliability requirements of automobile applications. Please note that the specifications of these models may be different from commercial models; therefore, designers should carefully review this data table. Specifications. Only the automobile -grade products can be used for car applications. Please contact your local simulation equipment customer representatives to obtain specific product ordering information and obtain a specific car reliability report of these models.

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