Datasheet

ManualsBrandsANALOG DEVICES ManualsPMICsPMIC - battery management Battery monitoring Li-Ion LQFP 48 (7x7) Surface-mount

Lithium Ion Battery Safety Monitor

AD8280

Rev. C

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other

rights of third parties that may result from its use. Specifications subject to change without notice. No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarks and registered trademarks are the property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700 www.analog.com

FEATURES

Wide supply voltage range: 6.0 V to 30.0 V

Multiple inputs can monitor 3 to 6 cell voltages

and 2 temperatures

Adjustable threshold levels: overvoltage, undervoltage,

overtemperature

Alarm options: separate or shared alarms

Extended temperature range performance

−40°C ≤ T

≤ +105°C

Can be daisy-chained

Internal reference

Powered from battery stack

LDO available to power isolator

Qualified for automotive applications

Extensive self-test feature aids in meeting ASIL/SIL

requirements

APPLICATIONS

Lithium ion battery backup monitor and threshold detection

Electric and hybrid electric vehicle

Industrial vehicle

Uninterruptible power supply

Wind and solar

GENERAL DESCRIPTION

The AD8280 is a hardware-only safety monitor for lithium ion

battery stacks. The part has inputs to monitor six battery cells

and two temperature sensors (either NTC or PTC thermistors).

The part is designed to be daisy-chained with other AD8280

devices to monitor a stack of significantly more than six cells

without the need for numerous isolators. Its output can be con-

figured for an independent or shared alarm state.

The AD8280 functions independently from a primary monitor

and contains its own reference and LDO, both of which are

powered completely from the battery cell stack. The reference, in

conjunction with external resistor dividers, is used to establish

trip points for the overvoltages and undervoltages. Each cell

channel contains programmable deglitching circuitry to prevent

alarms from transient input levels.

The AD8280 also has two digital pins that can be used to select

various combinations of inputs in the case where fewer than six

cells are to be monitored. Most important, it has a self-test feature,

making it suitable for high reliability applications, such as auto-

motive hybrid electric vehicles or higher voltage industrial usage,

such as uninterruptible power supplies. The AD8280 can function

over a temperature range of −40°C to +105°C.

FUNCTIONAL BLOCK DIAGRAM

I/V

CONVERTER

V/I

CONVERTER

VIN6

VIN5

VIN2

VIN1

UV OV

AIINOV

AIOUTOV

VT1

SEL0

SEL 1

VTOP

VBOT1

C6O

CT2

C1O

C1U

C6U

DE-

GLITCHING

DE-

GLITCHING

DE-

GLITCHING

DE-

GLITCHING

DE-

GLITCHING

DE-

GLITCHING

VIN3

VIN4

AD8280

CT1

VT2

AVOUTOV

ALARM

LOGIC

VIN0

LDO

REF

ENBO

ENBI

TOP

REF

DGT0

DGT1

LDO

TESTO

TESTI

SELF-

TEST

GENERATOR

BOT

LEVEL

SHIFTER

LEVEL

SHIFTER

AIOUTUV AIOUTOT

AIINUV AIINOT

DGT2

NPTC

ALRMSEL

AVOUTUV

AVOUTOT

VCC

VCCS

GND2

GND1

BOT1S

VBOT2

BOT2S

LDOS

VTOPS

LEVEL

SHIFTER

08911-001

Figure 1.

Summary of content (24 pages)

PAGE 1
Lithium Ion Battery Safety Monitor AD8280 FEATURES GENERAL DESCRIPTION Wide supply voltage range: 6.0 V to 30.
PAGE 2
AD8280 TABLE OF CONTENTS Features .............................................................................................. 1 Number of Cells Selection......................................................... 17 Applications....................................................................................... 1 Threshold Inputs ........................................................................ 17 General Description .........................................................................
PAGE 3
AD8280 SPECIFICATIONS VTOP = 7.5 V to 30 V, TA = −40°C to +105°C, unless otherwise noted. Table 1.
PAGE 4
AD8280 Parameter Self-Test Completion Time, tST Self-Test Valid Time, tSTV Delay Time for Self-Test Start, tRE Delay Time for Data Valid, tFE Rise Time for Self-Test Pulse, tR POWER SUPPLY Supply Voltage Range Quiescent Current Power Supply Enabled Power Supply Disabled Test Conditions/Comments Deglitch time = 0.0 sec Deglitch time > 0.0 sec Min 40 800 0.0 10 4.0 TESTI VTOP with respect to VBOTx LDO source current = 10.0 mA LDO source current = 0.0 mA Excluding LDO source current Rev.
PAGE 5
AD8280 ABSOLUTE MAXIMUM RATINGS THERMAL RESISTANCE Table 2. Parameter VTOP to VBOTx VIN0 to VBOTx VIN1 Through VIN6 Voltage to VBOTx VTx to VBOTx TESTI, ENBI to GNDx DGTx, SELx, NPTC to GNDx AVOUTxx to GNDx TOP, BOT to VBOTx Rating −0.3 V to +33 V −0.3 V to LDO + 0.3 V −0.3 V to VTOP + 0.3 V −0.3 V to LDO + 0.3 V −0.3 V to LDO + 0.3 V −0.3 V to LDO + 0.3 V −0.3 V to LDO + 0.3 V −0.3 V to VTOP + 0.
PAGE 6
AD8280 TOP BOT TESTO AIINOV AIINUV AIINOT ENBO REF FB LDOS LDO VCCS PIN CONFIGURATION AND FUNCTION DESCRIPTIONS 48 47 46 45 44 43 42 41 40 39 38 37 VBOT2 1 36 VCC VBOT2S 2 35 GND1 VBOT1S 3 34 GND2 VBOT1 4 33 NPTC VIN0 5 32 ALRMSEL VIN1 6 31 DGT0 VIN2 7 30 DGT1 VIN3 8 29 SEL0 VIN4 9 28 SEL1 VIN5 10 27 AVOUTOV VIN6 11 26 AVOUTUV 25 AVOUTOT AD8280 20 21 AIOUTOT ENBI OV 22 23 24 DGT2 19 UV 18 OT 17 AIOUTUV 16 AIOUTOV VT1 15
PAGE 7
AD8280 Pin No. 28 29 30 31 32 Mnemonic SEL1 SEL0 DGT1 DGT0 ALRMSEL 33 NPTC 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 GND2 GND1 VCC VCCS LDO LDOS FB REF ENBO AIINOT AIINUV AIINOV TESTO BOT TOP Description Digital Select Pin 1. Used with SEL0 to select channels to be used (see Table 5). Digital Select Pin 0. Used with SEL1 to select channels to be used (see Table 5). Digital Select Pin 1. Used with DGT0 and DGT2 to select deglitch time (see Table 7). Digital Select Pin 0.
PAGE 8
AD8280 TYPICAL PERFORMANCE CHARACTERISTICS SAMPLE SIZE = 2726 UNDERVOLTAGE OVERVOLTAGE NUMBER OF HITS 1200 900 600 1000 800 600 400 200 08911-003 300 –20 –10 0 10 20 0 –30 30 08911-006 NUMBER OF HITS UNDERVOLTAGE OVERVOLTAGE 1200 1500 0 –30 SAMPLE SIZE = 2726 1400 1800 –20 TRIP POINT ERROR (mV) UNDERVOLTAGE OVERVOLTAGE 2400 SAMPLE SIZE = 2726 2100 UNDERVOLTAGE OVERVOLTAGE 800 600 1500 1200 900 400 600 200 300 –20 –10 0 10 20 0 –30 30 –20 TRIP POINT ERROR (mV) –10
PAGE 9
AD8280 SAMPLE SIZE = 2726 SAMPLE SIZE = 2726 180 150 NUMBER OF HITS NUMBER OF HITS 200 150 100 50 –5 –4 –3 –2 –1 90 60 30 08911-009 0 120 08911-012 250 0 4.8 0 4.9 5.0 TRIP POINT ERROR (mV) Figure 9. Overtemperature Trip Point Error 180 300 150 120 90 250 200 150 60 100 30 50 47 48 49 50 0 1.2 51 08911-113 NUMBER OF HITS 350 08911-010 NUMBER OF HITS 5.4 SAMPLE SIZE = 2726 210 1.3 1.4 Figure 10. Overvoltage, Undervoltage, and Overtemperature Hysteresis 1.7 1.
PAGE 10
AD8280 75 25 VOLTAGE BETWEEN VIN0 AND VIN1 VIN1 AND VIN2 VIN2 AND VIN3 VIN3 AND VIN4 VIN4 AND VIN5 VIN5 AND VIN6 15 10 5 VIN1 TO VIN2 AND VIN5 TO VIN6 0 –5 –10 –15 65 60 55 50 45 40 35 –10 10 30 50 70 90 110 TEMPERATURE (°C) 25 –50 08911-013 –30 50 70 90 110 15 10 VOLTAGE BETWEEN VIN0 AND VIN1 VIN1 AND VIN2 VIN2 AND VIN3 VIN3 AND VIN4 VIN4 AND VIN5 VIN5 AND VIN6 70 UNDERVOLTAGE HYSTERESIS (mV) 5 0 –5 –10 VIN2 TO VIN3 AND VIN3 TO VIN4 –15 65 60 55 50 45 40 35 –10 10 30 50 70 90
PAGE 11
ENABLED SUPPLY CURRENT (mA) TRIP POINT ERROR (mV) 10 VOLTAGE BETWEEN VIN0 AND VIN1 VIN1 AND VIN2 VIN2 AND VIN3 VIN3 AND VIN4 VIN4 AND VIN5 VIN5 AND VIN6 5 0 –5 –15 6 10 14 18 22 26 30 STACK VOLTAGE (V) 2.5 2.0 2.0 1.5 1.0 1.0 DISABLED 0.5 0.5 0 0 6 10 14 18 22 26 30 STACK VOLTAGE (V) Figure 24. Supply Current vs. Stack Voltage (VIN6 – VIN0) Figure 21. Overvoltage Trip Point Error vs. Stack Voltage (VIN6 – VIN0) 5 1.40 0 1.
PAGE 12
AD8280 5.5 5.08 5.06 REF 5.05 VOLTAGE (V) 4.5 VOLTAGE (V) LDO 5.07 LDO 5.0 4.0 3.5 5.04 5.03 5.02 5.01 5.00 3.0 REF 0 5 10 15 20 25 30 SOURCE CURRENT (mA) 4.98 08911-030 2.5 Figure 27. LDO and Reference Voltage vs. LDO Source Current, Stack Voltage = 18.0 V 10 14 18 22 26 30 STACK VOLTAGE (V) Figure 30. LDO and Reference Voltage vs.
PAGE 13
AD8280 OV 1 5V/DIV OV 1 UV 2 OT TESTI 4 Figure 33. Alarm Fall Time CH2 5V CH4 5V M200ms 1.25ks/s A CH4 2.4V 800µs/pt Figure 36. TESTI and AVOUTxx, Deglitch Time = 0.1 sec, Self-Test Passes OV OV 1 UV UV 2 2 OT OT 3 TESTI 4 20ms/DIV 08911-024 3 TESTI 4 Figure 34. TESTI and AVOUTxx, Deglitch Time = 0.0 sec, Self-Test Passes CH1 5V CH3 5V CH2 5V CH4 5V M200ms 1.25ks/s A CH4 2.4V 800µs/pt 08911-049 5V/DIV 1 CH1 5V CH3 5V 08911-048 20ns/DIV 08911-036 3 Figure 37.
PAGE 14
AD8280 OV OV 1 5V/DIV 1 UV 2 CELL ALARM TRIPPED 2 CH1 5V CH3 5V CH2 5V CH4 5V M400ms 625s/s A CH4 2.4V 1.6ms/pt 200ms/DIV Figure 39. Alarm Condition Entering Self-Test, Part Passes Self-Test 08911-139 TESTI 4 08911-050 OT 3 Figure 42. Cell Voltage Change to Trip Alarm, Deglitch Time = 800 ms TESTI 4 OV 5V/DIV OV 1 2 CELL ALARM TRIPPED 08911-143 UV 2 OT 3 1sec/DIV 4µs/DIV Figure 40. Alarm Condition Entering Self-Test, Part Passes Self-Test (Enlarged) 1 Figure 43.
PAGE 15
AD8280 THEORY OF OPERATION Figure 44 shows a block diagram of the AD8280. The AD8280 is a threshold monitor that can be used to monitor up to six cell voltages and two temperature voltages. The part can also be used in a daisy-chain configuration to monitor as many cells as required.
PAGE 16
AD8280 APPLICATIONS INFORMATION TYPICAL CONNECTIONS TEMPERATURE INPUTS AND THERMISTOR SELECTION Figure 45 is a block diagram of the AD8280 typical connections. VT1 and VT2 are voltage inputs and are designed to work with thermistors that are configured as resistor dividers, as shown in Figure 45. The voltage at the top of the thermistor divider should be the +5 V output of the LDO. The LDO pin can source more current than the REF pin and is better suited to drive the thermistor dividers.
PAGE 17
AD8280 Also, if the resistor (RTOP) used in the top of the thermistor bridge circuit is less than 10 kΩ, another resistor (RIN) must be added in series to the input to the VTx pin (see Figure 46). The two resistors together must be greater than 10 kΩ (RTOP + RIN > 10 kΩ). This configuration is required only if VTH is not the AD8280 LDO. + + + + VIN5 VIN4 VIN3 VIN2 VTH VIN1 VIN0 RIN AD8280 VTx THERMISTOR 08911-042 RTOP VIN6 Figure 48.
PAGE 18
AD8280 TOP AND BOTTOM PART DESIGNATION When configured in a daisy chain, the AD8280 operates differently, depending on where it is in the chain: top part (highest potential), middle part, or bottom part (lowest potential). The TOP and BOT pins are used to designate the location of each part in the daisy chain. Table 6 is the logic table for identifying the location of the part in the daisy chain or, when not used in a daisy chain, identifying it as a single (standalone) part.
PAGE 19
AD8280 100nF 10µF 0.1µF T1/T2 VTOPx UV OV OT TESTO AIINxx ENBO T1 NTC T2 10kΩ 10nF + VIN6 + VIN5 + VIN4 + VIN3 + VIN2 SEL1 VIN1 BOT VIN0 TOP + 1.0µF VCCx LDOx UV REF REF/FB 10kΩ DGT0 OV REF OT REF 2.
PAGE 20
AD8280 ENABLING AND DISABLING THE AD8280 The AD8280 can be disabled or put into a standby mode by bringing the ENBI pin to logic low, lowering the quiescent current of the AD8280 from a maximum of 2.0 mA to 1.0 μA and dropping the LDO and reference output to 0 V. Bringing the ENBI pin to a logic high takes the part out of standby mode and enables it.
PAGE 21
AD8280 NORMAL OPERATION UNALARMED AIOUTxx/AVOUTxx ALARMED AIOUTxx/AVOUTxx DURING SELF-TEST MODE TESTI AIOUTxx/AVOUTxx TEST OK AIOUTxx/AVOUTxx TEST FAILS HIGH AT FALLING EDGE OF TESTI: PART FAILS SELF-TEST LOW AT FALLING EDGE OF TESTI: PART PASSES SELF-TEST 08911-045 AIOUTxx/AVOUTxx ALARMED TEST OK Figure 51.
PAGE 22
AD8280 NO ALARM WHEN SELF-TEST IS INITIATED 1 TESTI 0 1 AVOUTxx SELF-TEST PASS 0 tSTV 1 AVOUTxx SELF-TEST FAIL 0 tFE tRE tST ALARM WHEN SELF-TEST IS INITIATED 1 TESTI 0 1 AVOUTxx SELF-TEST PASS 0 tSTV 1 AVOUTxx SELF-TEST FAIL tRE 0 tST NOTES 1. tRE IS THE TIME FROM THE RISING EDGE OF THE TEST PULSE (TESTI) TO THE START OF THE SELF-TEST. 2. tST IS THE TIME FROM THE RISING EDGE OF THE TEST PULSE UNTIL THE PART COMPLETES ITS SELF-TEST (TEST PULSE MUST BE LONGER THAN tST MAX). 3.
PAGE 23
AD8280 Sample Calculation PROTECTION COMPONENTS AND PULL-UP/ PULL-DOWN RESISTORS As shown in Figure 45, several devices are added to provide protection in a high voltage environment. Zener Diode Z1 ensures that the six-cell stack voltage does not significantly exceed the maximum 30 V across the part. It is recommended that a 33 V rated Zener diode be used for Z1.
PAGE 24
AD8280 OUTLINE DIMENSIONS 9.20 9.00 SQ 8.80 1.60 MAX 37 48 36 1 PIN 1 7.20 7.00 SQ 6.80 TOP VIEW 1.45 1.40 1.35 0.15 0.05 SEATING PLANE 0.20 0.09 7° 3.5° 0° 0.08 COPLANARITY VIEW A (PINS DOWN) 25 12 13 VIEW A 0.50 BSC LEAD PITCH 24 0.27 0.22 0.17 ROTATED 90° CCW COMPLIANT TO JEDEC STANDARDS MS-026-BBC 051706-A 0.75 0.60 0.45 Figure 53.