toring battery charge and discharge currents in note-books, cell phones, and other portable equipment.♦2.5V to 5.5V Operating Supply VoltageThese devices feature a wide -0.1V to +28V input com-♦20µA Quiescent Supply Currentmon-mode voltage range, low 20µA supply current with♦0.4mV (max) Input Offset VoltageV♦Gain Accuracy Better than 1% (max)1.0%. The input common-mode range is independentOSless than 0.4mV, and a gain accuracy better thanof the supply voltage, ensuring that the current-sense♦SIGN Output Indicates Current Polarity
information remains accurate even when the measure-♦Two Iment rail is shorted to ground.
25µµA/mV (MAX9928T)OUT Transconductance Versions Available
A/mV (MAX9928F)
The MAX9928F/MAX9928T feature a current output withtransconductance ratios of 5µA/mV and 2µA/mV, respec-♦Two V20V/V (MAX9929T)OUTGain Versions Available
tively. An external resistor converts the output current to a50V/V (MAX9929F)
voltage, allowing adjustable gain so that the input sensevoltage can be matched to the maximum ADC input♦Pin Compatible with the MAX4372 in UCSPswing. The MAX9929F/MAX9929T have a voltage output♦Available in Ultra-Small 3x2 UCSP
and integrate a 10kΩoutput resistor for fixed voltage(1mm x 1.5mm) and 8-Pin µMAX Packages
gains of 50V/V and 20V/V, respectively.
ApplicationsA digital SIGN output indicates direction of current flow,so the user can utilize the full ADC input range for mea-Monitoring Charge/Discharge Currents insuring both charging and discharging currents.
Portable/Battery-Powered SystemsThe MAX9928/MAX9929 are fully specified over the -40°CNotebook Computers
to +125°C automotive temperature range, and availableGeneral-System/Board-Level Current Monitoringin 6-bump UCSP™ (1mm x 1.5mm) and 8-pin µMAX®packages. The UCSP package is bump-to-bump com-Smart-Battery Packs/Chargerspatible with the MAX4372_EBT.
Precision Current SourcesUCSP is a trademark and µMAX is a registered trademark ofSmart Cell Phones
Maxim Integrated Products, Inc.Super Capacitor Charge/Discharge
Pin Configurations and Typical Operating Circuit appear atend of data sheet.Ordering InformationPARTOUTPUT TYPEGAINPIN-PACKAGETOP MARKPKG CODEMAX9928FAUA+CurrentGm = 5µA/mV8 µMAX—U8-1MAX9928FABT+T†CurrentGm = 5µA/mV3x2 UCSP+AAAR61A1+1MAX9928TAUA+CurrentGm = 2µA/mV8 µMAX—U8-1MAX9928TABT+T†CurrentGm = 2µA/mV3x2 UCSP+AACR61A1+1MAX9929FAUA+VoltageAV = 50V/V8 µMAX—U8-1MAX9929FABT+T†VoltageAV = 50V/V3x2 UCSP+AABR61A1+1MAX9929TAUA+*VoltageAV = 20V/V8 µMAX—U8-1MAX9929TABT+*†VoltageAV = 20V/V3x2 UCSP+AADR61A1+1Note:All devices are specified over the -40°C to +125°C operating temperature range.+Denotes a lead-free/RoHS-compliant package.*Future product—contact factory for availability.†The MAX9928_ABT and the MAX9929_ABT use Package Code R61A1+1 with backside coating to minimize die chipping.________________________________________________________________Maxim Integrated Products1
For pricing, delivery, and ordering information,please contact Maxim Directat 1-888-629-4642,or visit Maxim’s website at www.maxim-ic.com.MAX9928/MAX9929-0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense AmplifiersMAX9928/MAX9929ABSOLUTE MAXIMUM RATINGS
VCC, SIGN to GND...................................................-0.3V to +6VRS+, RS- to GND....................................................-0.3V to +30VOUT to GND...............................................-0.3V to (VCC+ 0.3V)Differential Input Voltage (VRS+- VRS-)..............................±30VOUT, SIGN Short Circuit to VCCor GND ...................ContinuousCurrent into Any Pin..........................................................±20mAContinuous Power Dissipation (TA= +70°C)6-Bump 1mm x 1.5mm UCSP
(derate 3.9mW/°C above +70°C)............................308.3mW8-Pin µMAX (derate 4.8mW/°C above +70°C).............388mW
Operating Temperature Range ........................-40°C to +125°CStorage Temperature Range ............................-65°C to +150°CJunction Temperature .....................................................+150°CLead Temperature (soldering, 10s).................................+300°CLead Temperature (reflow)..............................................+260°CBump Temperature (reflow).............................................+260°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functionaloperation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure toabsolute maximum rating conditions for extended periods may affect device reliability.ELECTRICAL CHARACTERISTICS
(VRS+= -0.1V to +28V, VCC= 3.3V, VSENSE= (VRS+- VRS-) = 0V, ROUT= 10kΩfor MAX9928_, TA= -40°C to +125°C, unless other-wise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETERSYMBOLCONDITIONSTA = +25°CTA = -40°C to +125°CTA = +25°CTA = -40°C to +125°C-0.1TA = +25°CTA = -40°C to +125°CTA = +25°CTA = -40°C to +125°C93876054±50±1255020TA = +25°CTA = -40°C to +125°CTA = +25°CTA = -40°C to +125°C52±0.3±0.3±1.0±2.5±1.0±2.8µA/mV%mVV/V72104dB±0.6MINTYP±0.1MAX±0.4±0.8±1.0±3.0+28VmVUNITSAMPLIFIER DC ELECTRICAL CHARACTERISTICSVRS+ = 3.6VInput Offset Voltage (Note 2)VOSVRS+ = -0.1VCommon-Mode Input RangeVCMR(Note 3)2V ≤ VRS+ ≤ 28VCommon-Mode Rejection RatioCMRR-0.1V ≤ VRS+ ≤+2VMAX992_FMAX992_TMAX9929FMAX9929TMAX9929_,VRS+ = 3.6VMAX9929_,VRS+ = -0.1VGMMAX9928FMAX9928TFull-Scale Sense Voltage (Note 2)Gain (Note 2)VSENSEAVGain Accuracy (Notes 2, 6)Transconductance (Note 2)2_______________________________________________________________________________________
-0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense AmplifiersELECTRICAL CHARACTERISTICS (continued)
(VRS+= -0.1V to +28V, VCC= 3.3V, VSENSE= (VRS+- VRS-) = 0V, ROUT= 10kΩfor MAX9928_, TA= -40°C to +125°C, unless other-wise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSMAX9928_,TA = +25°C±0.3±1.0Transconductance AccuracyVRS+ = 3.6VTA = -40°C to +125°C±2.5(Note 2)MAX9928_,TA = +25°C±0.3±1.0%VRS+ = -0.1VTA = -40°C to +125°C±2.8Input Bias Current (Note 4)I2V ≤ V01.66RS+, IRS-RS+ ≤ 28V-0.1V ≤ VRS+ ≤ +2V-80+6µAInput Offset Bias Current (Note 4)I2V ≤ V±0.05±1OSRS+ ≤ 28V-0.1V ≤ VRS+ ≤ +2V±0.2±2µAInput Leakage CurrentIRS+, IRS-VCC = 0V, VRS+ = VRS- = 28V (Note 5)0.051.0µAOutput ResistanceRMAX9928_5MΩOUTMAX9929_6.41013.6kΩMAX9928_, ROUT = 10kΩ(VCC -(VCC -Output High Voltage (Note 6)V0.1)0.45)OHMAX9929_(VVCC -(VCC -0.1)0.45)Minimum Output Voltage (Note 7)VT0.252.0OLMAX9929_A = +25°CTA = -40°C to +125°C15mVMinimum Output Current (Note 7)IT0.0250.2OLMAX9928_A = +25°CTA = -40°C to +125°C1.5µASIGN COMPARATOR DC ELECTRICAL CHARACTERISTICSTA = +25°C-1.6-1.2-0.5Discharge to Charge Trip PointVRS+ = 3.6VTA = -40°C to +125°C-2.15-0.15(Note 8)VTDCTA = +25°C-2.5-1.2+0.25mVVRS+ = -0.1VTA = -40°C to +125°C-4.6+2.3Charge to Discharge Trip PointTA = +25°C-1.8(Note 8)VTCDVRS+ = 3.6VVTmVRS+ = -0.1VA = +25°C-1.8Hysteresis WidthVHYSVRS+ = 3.6V,-0.1VTA = +25°C0.6mV_______________________________________________________________________________________3
MAX9928/MAX9929-0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense AmplifiersMAX9928/MAX9929ELECTRICAL CHARACTERISTICS (continued)
(VRS+= -0.1V to +28V, VCC= 3.3V, VSENSE= (VRS+- VRS-) = 0V, ROUT= 10kΩfor MAX9928_, TA= -40°C to +125°C, unless other-wise noted. Typical values are at TA = +25°C.) (Note 1)PARAMETERCommon-Mode Input Range(Note 9)Common-Mode Rejection Ratio(Note 9)Output Low VoltageOutput High VoltageInternal Pullup ResistorPOWER SUPPLYSupply Voltage Range (Note 10)Amplifier Power-Supply RejectionRatio (Note 10)Comparator Power-SupplyRejection RatioQuiescent Supply CurrentVCCPSRRAPSRRCICCTA = +25°CTA = -40°C to +125°CVRS+ = 3.6VVRS+ = -0.1VVRS+ = 3.6VVRS+ = -0.1V2V ≤ VRS+ ≤ 28V-0.1V ≤ VRS+ < +2VMAX992_F, VSENSE = 50mVMAX992_T, VSENSE = 125mVMAX992_F, VSENSE =5mV to 50mV stepVRS+ = 3.6V,CLOAD = 10pF,ROUT = 10kΩ forMAX9928_MAX992_F, VSENSE =50mV to 5mV stepMAX992_T, VSENSE =5mV to 125mV stepMAX992_T, VSENSE =125mV to 5mV step2.52.872669086908620115150125615µs813302005.55.5VdBdBµASYMBOLVCMRCMRRVOLVOHRPULL-UP2V ≤ VRS+ ≤ 28V-0.1V ≤ VRS+ ≤ +2VISINK = 100µACONDITIONSMIN-0.1102740.03(VCC -0.01)10.1(VCC -0.04)TYPMAX+28UNITSVdBVVMΩAC ELECTRICAL CHARACTERISTICS-3dB BandwidthBWkHzOUT Settling to 1% of Final ValuetSET4_______________________________________________________________________________________
-0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense AmplifiersELECTRICAL CHARACTERISTICS (continued)
(VRS+= -0.1V to +28V, VCC= 3.3V, VSENSE= (VRS+- VRS-) = 0V, ROUT= 10kΩ, for MAX9928_, TA= -40°C to +125°C, unless other-wise noted. Typical values are at TA = +25°C.) (Note 1)PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSIGN Comparator PropagationOverdrive = 1mV80Delay (Low to High)tPROP_LHOverdrive = 5mV30µsSIGN Comparator Propagation50Delay (High to Low)tOverdrive = 1mVPROP_HLOverdrive = 5mV13µsPower-Up Time to 1% of FinalVSENSE = 50mV for MAX992_F,ValueVSENSE = 125mV for MAX992_T,50µsVRS+ = 3.6V, CLOAD = 10pF100mV ≤ VSENSE ≤ 50mV for MAX992_F,Saturation Recovery Time250mV ≤ VSENSE ≤ 125mV for MAX992_T,4msVRS+ = 3.6V, CLOAD = 10pFNote 1:All devices are 100% production tested at TA= +25°C. All temperature limits are guaranteed by design.Note 2:VOSis extrapolated from two point transconductance and gain accuracy tests. Measurements are made at VSENSE=
+5mV and VSENSE= +50mV for MAX992_F and VSENSE=+5mV and VSENSE= +125mV for MAX992_T. These measure-ments are also used to test the full-scale sense voltage, transconductance, and gain. These VOSspecifications are for thetrimmed direction only (VRS+> VRS-). For current flowing in the opposite direction (VRS-> VRS+), VOSis ±1mV (max) at+25°C and ±1.8mV (max) over temperature, when VRS+is at 3.6V. See the Detailed Descriptionfor more information.
Note 3:Guaranteed by common-mode rejection ratio. Extrapolated VOSas described in Note 2 is used to calculate common-mode
rejection ratio.
Note 4:Includes input bias current of SIGN comparator.
Note 5:Leakage in to RS+ or RS- when VCC= 0V. Includes input leakage current of SIGN comparator. This specification does not
add to the bias current.
Note 6:Output voltage should be 650mV below VCCto achieve full accuracy.
Note 7:IOLis the minimum output current in the VSENSE- IOUTtransfer characteristics. VOLis the minimum output voltage in the
VSENSE- VOUTtransfer characteristic.
Note 8:VSENSEvoltage required to switch comparator.
Note 9:Discharge to charge trip point is functionally tested at VCM= -0.1V, +3.6V, and +28V.
Note 10:Guaranteed by PSRR test. Extrapolated VOSas described in Note 2 is used to calculate the power-supply rejection ratio.
VSENSEhas to be such that the output voltage is 650mV below VCCto achieve full accuracy.
_______________________________________________________________________________________5
MAX9928/MAX9929-0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense AmplifiersMAX9928/MAX9929Typical Operating Characteristics(VCC= 3.3V, VRS+= 12V, TA= +25°C, unless otherwise noted.)
GAIN ACCURACYHISTOGRAM
MAX9928 toc01MAX9928 toc02VOS HISTOGRAM
454035FREQUENCY (%)302520151050
-0.40-0.30-0.20-0.100
0.10
0.200.300.40
50
AV = 50V/V3025FREQUENCY (%)201510
AV = 50V/VOFFSET VOLTAGE
vs. COMMON-MODE VOLTAGE
1.5OFFSET VOLTAGE (mV)1.00.50-0.5-1.0-1.5
MAX9928 toc032.0
-1.0-0.8-0.6-0.4-0.200.20.40.60.81.0
GAIN ACCURACY (%)
-2.0
-1012328COMMON-MODE VOLTAGE (V)
VOS (mV)
OFFSET VOLTAGE vs. TEMPERATURE
MAX9928 toc04SUPPLY CURRENTvs. SUPPLY VOLTAGE
VSENSE = 0VVRS+ = 0VMAX9928 toc05SUPPLY CURRENT
vs. COMMON-MODE VOLTAGEMAX9928 toc061.00.80.6OFFSET VOLTAGE (mV)0.40.20-0.2-0.4-0.6-0.8-1.0
VCM = 3.6V150125SUPPLY CURRENT (μA)1007550250
150
120SUPPLY CURRENT (μA)90
VCC = 5.5V60
VCC = 2.5V30
VRS+ = 3.6V0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
-0.500.51.01.52.028SUPPLY VOLTAGE (V)
COMMON-MODE VOLTAGE (V)
-40-25-105203550658095110125
TEMPERATURE (°C)
SUPPLY CURRENTvs. TEMPERATURE
MAX9928 toc07INPUT BIAS CURRENTvs. COMMON-MODE VOLTAGE
MAX9928 toc08MAX9928FIOUT vs. VSENSE
VOUT = 0VTA = -40°CMAX9928 toc09150125SUPPLY CURRENT (μA)1007550
VSENSE = 0VVRS+ = 0V100INPUT BIAS CURRENT (μA)-10-20-30-40-50-60-70-80
2500
2000
TA = +25°CTA = +125°C1000
VRS+ = 3.6V250-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
IOUT (μA)-2-0.10281500
500
00
0.1
0.2
0.3
0.4
0.5
VSENSE (V)
246810COMMON-MODE VOLTAGE (V)
6_______________________________________________________________________________________
-0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense AmplifiersTypical Operating Characteristics (continued)(VCC= 3.3V, VRS+= 12V, TA= +25°C, unless otherwise noted.)
MAX9929FMAX9929FMAX9928T IOUT vs. VSENSE
VOUT vs. VSENSE
VOUT vs. VSENSE
1600
01613.4
21Vc1occOUT = 0Vto t8 28ToA = -40°Ct 82929999X9A5
X3.2XMAAMM1200TA = +125°CVCC = 5.5V43.0TA = +25°C)A))μVV((2.8( TU800
TTTA = +125°CUUOITA = -40°CO3
OVV2.6TVA = +25°CCC = 3.3V2400
VCC = 2.7V2.4VCC = 2.5V1
2.2002.0
0
0.2
0.40.6
0.8
0
20
40
60
80
100
120
140
30405060708090
VSENSE (V)
VSENSE (mV)
VSENSE (mV)
MAX9929TMAX9929TGAIN ACCURACYVOUT vs. VSENSE
VOUT vs. VSENSE
vs. SUPPLY VOLTAGE
633.4
4111.0
51ccTcoooA = -40°Cttt 888222999990.895
X3.2XAAXMM0.6AMVCC = 5.5V3.0)%4
TA = +25°C( 0.4YC))VVN0.2((2.8A T3
TT°CRUUA = +125UOOC0VVVCCC = 3.3V2.6A N-0.22IVCC = 2.7V2.4AG-0.4VCC = 2.5V1-0.62.2-0.802.0
-1.0
0
50
100
150
200
250
300
350
1001201401601802002202.53.03.54.04.55.05.5
VSENSE (mV)VSENSE (mV)
SUPPLY VOLTAGE (V)
MINIMUM OUTPUT VOLTAGE
SMALL-SIGNAL GAINvs. TEMPERATURE
GAIN ACCURACY vs. TEMPERATURE
vs. FREQUENCY
5.061.071135
81ccocoott4.5 t80.8 VCM = 3.6V 88222999)999VXAXXmMAM(4.00.632
MAX992_FAM EG)A%T3.5(0.4
L OV3.0YC0.2)B29
ATRd(UP2.5UCT0 NIAUCO 2.0A MN-0.2G26
IUM1.5AG-0.4IMAX992_TNIM1.0-0.623
0.5-0.80
-1.0
20-40-25-105203550658095110125
-40-25-105203550658095110125
0.01
0.11101001000
TEMPERATURE (°C)
TEMPERATURE (°C)
FREQUENCY (kHz)
_______________________________________________________________________________________7
MAX9928/MAX9929-0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense AmplifiersMAX9928/MAX9929Typical Operating Characteristics (continued)(VCC= 3.3V, VRS+= 12V, TA= +25°C, unless otherwise noted.)
MAX9929F LARGE-SIGNALTRANSIENT RESPONSE
MAX9928 toc21MAX9928 toc20CMRR vs. FREQUENCY
MAX9928 toc19PSRR vs. FREQUENCY
200-20PSRR (dB)-40-60-80-100
VOUT
120
90CMRR (dB)VSENSE
50mV/div
60
301V/div
010
100
1k
10k
100k
1M
FREQUENCY (Hz)
-120
0.1
1
10
100
1k
10k
100k
100μs/div
FREQUENCY (Hz)
MAX9929T LARGE-SIGNALTRANSIENT RESPONSE
MAX9928 toc22VSIGN AND VOUTvs. VSENSE
3210VOUT (mV)150100500-3
-2
-1
0VSENSE (mV)
1
2
3
MAX9928 toc23OVERDRIVE RECOVERYMAX9928 toc244VSIGN (V)VSENSE
20mV/div
VSENSE100mV/divVOUT1V/div
VOUT500mV/div100μs/div400μs/divCOMPARATOR PROPAGATION DELAY(RS+ = 3.6V, 5mV OVERDRIVE)MAX9928 toc25POWER-UP DELAYMAX9928 toc26VSENSE2mV/divVCC1V/divVOUT1V/divVOUT1V/div40μs/div40μs/div8_______________________________________________________________________________________-0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense AmplifiersPin DescriptionPINBUMPµMAXUCSPNAMEFUNCTION1B3RS-Negative Current-Sense Input. Load-side connection for the external sense resistor.SIGN Output. Indicates polarity of VSENSE.2B2SIGNSIGN = H indicates VRS+ > VRS-SIGN = L indicates VRS+ < VRS-3B1RS+Positive Current-Sense Input. Power-side connection to the external sense resistor.4, 5—N.C.No Connection. Not internally connected.6A1VCCSupply Voltage Input. Bypass to GND with a 0.1µF capacitor.7A2GNDCircuit Ground8A3OUTCurrent-Sense Output. MAX9928: Current output (IOUT is proportional to |VSENSE|). MAX9929:Voltage output (VOUT is proportional to |VSENSE|).Detailed Description+VThe MAX9928_/MAX9929_ micropower uni-/bidirectional,The amplifier is configured for either positive VSENSEvs. -VSENSESENSEorcurrent-sense amplifiers feature -0.1V to +28V inputnegative VSENSEby the SIGN comparator. The com-common-mode range that is independent of the supplyparator has a built-in offset skew of -1.2mV so that ran-voltage. This wide input voltage range feature allows thedom offsets in the comparator do not affect themonitoring of the current flow out of a power supply dur-precision of IOUT(VOUT) with positive VSENSE. Theing short-circuit/fault conditions, and also enables high-comparator has a small amount of hysteresis (typicallyside current sensing at voltages far in excess of the0.6mV) to prevent its output from oscillating at thesupply voltage (VCC). The MAX9928_/MAX9929_ oper-crossover sense voltage. The ideal transfer characteris-ate from a 2.5V to 5.5V single supply and draw a lowtic of IOUT(VOUT) and the output of the comparator20µA quiescent supply current.
(SIGN) is shown in Figure 2.
Current flows through the sense resistor, generating aThe amplifier Vsense voltage VSENSE(Figure 1). The comparator sens-voltages (VOSis only trimmed for the positive VSENSERS+> VRS-). The SIGN comparator reconfig-es the direction of the sense voltage and configures theures the internal structure of the amplifier to work withamplifier for either positive or negative sense voltagesnegative VSENSEvoltages (VRS-> Vby controlling the S1 and S2 switches.
sion VRS+) and the preci-For positive Vis slightly impacted. See details in the OStrim is no longer effective and the resulting VElectricalOSSENSEvoltage, the amplifier’s invertinginput is high impedance and equals VCharacteristicsNote 2. The user can choose the direc-IN- VSENSE. Theamplifier’s output drives the base of Q1, forcing its non-tion that needs the best precision to be the directioninverting input terminal to (Vwhere VRS+> VRS-. For example, when monitoring Li+current to flow through RIN- VSENSE); this causes abattery currents, the discharge current should be VRS+>Transistor Q2 and the current mirror amplify the currentG1equal to |VSENSE|/RG1.Vby a factor of M.
range. When the battery charger is plugged in, theRS-to give the best accuracy over the largest dynamiccharge current flows in the opposite direction and isFor negative Vusually much larger, and a higher Ving input is high impedance and the voltage on RS- ter-SENSEvoltage, the amplifier’s noninvert-tolerated. See the Typical Operating CircuitOSerror can be.
minal equals VIN + VSENSE. The amplifier’s outputdrives the base of Q1 forcing its inverting input terminalFor applications with unidirectional currents (e.g., bat-to match the voltage at the noninverting input terminal;tery discharge only), the SIGN output can be ignored.this causes a current to flow through RNote that as V|V. Again, transistor Q2 and the current mir-G2equal tofor the MAX9928 or VSENSEincreases, the output current (IOUTOUT/10kΩfor the MAX9929) alsoror amplify the current by a factor of M.
SENSE|/RG2increases. This additional current is supplied from VCC.
_______________________________________________________________________________________9
MAX9928/MAX9929-0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense AmplifiersMAX9928/MAX99292.5V TO 5.5VVCCRC180kΩVCCMAX9928_MAX9929_C1MΩSIGNTO μCRC280kΩCURRENTMIRRORVIN-0.1V TO +28V(VBATT)+RS+RG180kΩS2OUTTO ADCRSENSEVSENSERS-RG280kΩAS1Q1Q210kΩ*-TOLOAD/CHARGER*INTERNAL 10kΩ RESISTOR FOR MAX9929_ ONLY.GNDFigure 1. Functional DiagramFor both positive and negative VSENSEvoltages, thecurrent flowing out of the current mirror is equal to:
IOUT= M x |VSENSE|/RG1For the MAX9928F/MAX9928T, the transconductance ofthe device is trimmed so that IOUT/|VSENSE| = 5µA/mVand 2µA/mV, respectively. For the MAX9929F/MAX9929T, the voltage gain of the device is trimmedso that VOUT/|VSENSE| = 50V/V and 20V/V, respectively.The SIGN output from the comparator indicates thepolarity of VSENSE.
-3.0-1.8-1.20VSENSE (mV)SIGN1.02.03.0Current Output (MAX9928_)The output voltage equation for the MAX9928_ is givenbelow:
VOUT= (RSENSEx ILOAD) x (Gm X ROUT)
where VOUT= the desired full-scale output voltage,ILOAD= the full-scale current being sensed, RSENSE=the current-sense resistor, ROUT= the voltage-settingresistor, and Gm= MAX9928F transconductance(5µA/mV) or MAX9928T transconductance (2µA/mV).The full-scale output voltage range can be set bychanging the ROUTresistor value. The above equationcan be modified to determine the ROUTrequired for aparticular full-scale range:
ROUT= (VOUT)/(ILOADx RSENSEx Gm)
-3.0-1.8-1.20VSENSE (mV)IOUT (VOUT)1.02.03.0( ) FOR THE MAX9929_.Figure 2. Ideal Transfer Characteristics with 0mV Amplifier InputOffset Voltage and -1mV Comparator Input Offset Voltage10
______________________________________________________________________________________
-0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense AmplifiersOUT is a high-impedance current source and can drivean unlimited amount of capacitance.
•Inductance: ponent to IIf there is a large high-frequency com-Voltage Output (MAX9929_)resistors have the highest inductance, while metalSENSE, keep inductance low. Wire-woundThe output voltage equation for the MAX9929_ is givenfilm is somewhat better. Low-inductance metal-filmbelow:
resistors are available. Instead of being spiralwrapped around a core, as in metal film or wire-VOUT= (RSENSEx ILOAD) x (AV)
wound resistors, these are a straight band of metal.where VThey are made in values under 1Ω.
I= the full-scale current being sensed, ROUT= the desired full-scale output voltage,LOADSENSE=the current-sense resistor, AV= MAX9929F voltageUse in Systems with Super Capacitors gain (50V/V) or MAX9929T voltage gain = (20V/V).
Since the input common-mode voltage range of theMAX9928/MAX9929 extends all the way from -0.1V toSIGN Output28V, they are ideal to use in applications that requireThe current/voltage at OUT indicates magnitude. Theuse of super capacitors for temporary or emergencySIGN output indicates the current’s direction. The SIGNenergy storage systems. Some modern industrial andcomparator compares RS+ to RS-. The sign output isautomotive systems use multifarad (1F–50F) capacitorhigh when RS+ is greater than RS- indicating positivebanks to supply enough energy to keep critical sys-current flow. The sign output is low when RS- is greatertems alive even if the primary power source is removedthan RS+ indicating negative current flow. In battery-or temporarily disabled. Unlike batteries, these capaci-operated systems, this is useful for determiningtors can discharge all the way down to 0V. Thewhether the battery is charging or discharging. TheMAX9928/MAX9929 can continuously help monitor theirSIGN output might not correctly indicate the direction ofhealth and state of charge/discharge.
load current when V(see Figure 2). Comparator hysteresis of 0.6mV pre-SENSEis between -1.8mV to -1.2mVUCSP Applications Informationvents oscillation of SIGN output. If current direction isFor the latest application details on UCSP construction,not needed, leave SIGN unconnected.
dimensions, tape carrier information, PCB techniques,Applications Informationbump-pad layout, and recommended reflow tempera-ture profile, as well as the latest information on reliabilityChoosing RSENSEtesting results, go to Maxim’s website at www.maxim-The MAX9928_/MAX9929_ operate over a wide varietyic.com/ucsp to find Application Note 1891:of current ranges with different sense resistors. AdjustUnderstanding the Basics of the Wafer-Level Chip-the Rvalue to monitor higher or lower current lev-Scale Package (WL-CSP).els. Select RSENSESENSEusing these guidelines:
Chip Information•Voltage Loss: A high RPROCESS: BiCMOS
power-source voltage to drop due to IR loss. FSENSEvalue causes theorleast voltage loss, use the lowest RSENSEvalue.•Accuracy: rents to be measured more accurately. This isA high RSENSEvalue allows lower cur-because offsets become less significant when thesense voltage is larger.
•Efficiency and Power Dissipation: levels, the I2R losses in RAt high currentSENSEmight be significant.Take this into consideration when choosing the resis-tor value and power dissipation (wattage) rating.Also, if the sense resistor is allowed to heat up exces-sively, its value could drift.
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MAX9928/MAX9929-0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense AmplifiersMAX9928/MAX9929Pin ConfigurationsTOP VIEWRS-SIGNRS+N.C.1234+8OUTGNDVCCN.C.BRS+TOP VIEW(BUMPS ON THE BOTTOM)1AVCC2GND3OUTMAX9928_MAX9929_765MAX9928_MAX9929_SIGNRS-μMAXUCSP(1mm x 1.5mm)Typical Operating CircuitWALL-CUBECHARGERVIN-0.1V TO+28VRS+RSENSELOADμCDIGITALINPUTADCROUT*GND*FOR THE MAX9928_ ONLYRS-2.5V TO5.5V0.1μFVCCMAX9928_MAX9929_SIGNOUTGND12______________________________________________________________________________________
-0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense AmplifiersPackage Information(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline informationgo to www.maxim-ic.com/packages.)
SPE.DXAMUL8αα______________________________________________________________________________________13
MAX9928/MAX9929-0.1V to +28V Input Range, Micropower, Uni-/Bidirectional, Current-Sense AmplifiersMAX9928/MAX9929Package Information (continued)(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline informationgo to www.maxim-ic.com/packages.)
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses areimplied. Maxim reserves the right to change the circuitry and specifications without notice at any time.14____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600©2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
UCSP.EPS
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