MAX1924XEEE+ ,Advanced Li+ Battery-Pack ProtectorsApplications Circuits appear at end of data sheet.____ Maxim Integrated Products 1For pricing, deli ..
MAX1925ETC-T ,Switch-Mode 1-Cell Li+ ChargersApplications12 Thin QFNMAX1925ETC -40°C to +85°C 4.5V to 6.1V4mm x 4mmDigital Cameras12 Thin QFNSel ..
MAX1926ETC ,Switch-Mode 1-Cell Li+ ChargersApplications12 Thin QFNMAX1925ETC -40°C to +85°C 4.5V to 6.1V4mm x 4mmDigital Cameras12 Thin QFNSel ..
MAX1926ETC ,Switch-Mode 1-Cell Li+ ChargersELECTRICAL CHARACTERISTICS(V = V = 0, V = V = V = 5V, V = V = V = 4V, THRM = 10kΩ to GND, C = 100nF ..
MAX1926ETC+ ,Switch-Mode 1-Cell Li+ ChargersELECTRICAL CHARACTERISTICS(V = V = 0, V = V = V = 5V, V = V = V = 4V, THRM = 10kΩ to GND, C = 100nF ..
MAX1926ETC+T ,Switch-Mode 1-Cell Li+ Chargersfeatures include automatic input power♦ Set Charge Current with One Resistordetection (ACON output) ..
MAX488EESA ,15kV ESD-Protected / Slew-Rate-Limited / Low-Power / RS-485/RS-422 TransceiversELECTRICAL CHARACTERISTICS(V = 5V ±5%, T = T to T , unless otherwise noted.) (Notes 1, 2)CC A MIN M ..
MAX488EESA ,15kV ESD-Protected / Slew-Rate-Limited / Low-Power / RS-485/RS-422 TransceiversApplicationsIndustrial-Control Local Area Networks__Selection TableRECEIVER/ QUIESCENT NUMBER OFPAR ..
MAX488EESA ,15kV ESD-Protected / Slew-Rate-Limited / Low-Power / RS-485/RS-422 TransceiversApplicationsMAX481EESA -40°C to +85°C 8 SOLow-Power RS-485 TransceiversOrdering Information continu ..
MAX488EESA+ ,±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceiversapplications that are not ESD sensitive see the pin-and function-compatible MAX481, MAX483, MAX485, ..
MAX488EESA+T ,±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 TransceiversELECTRICAL CHARACTERISTICS(V = 5V ±5%, T = T to T , unless otherwise noted.) (Notes 1, 2)CC A MIN M ..
MAX488EPA ,Low-Power / Slew-Rate-Limited RS-485/RS-422 TransceiversFeaturesThe MAX481, MAX483, MAX485, MAX487–MAX491, and' In µMAX Package: Smallest 8-Pin SOMAX1487 a ..
MAX1924VEEE+-MAX1924XEEE+
Advanced Li+ Battery-Pack Protectors
General DescriptionThe MAX1894/MAX1924 are lithium-ion/lithium-polymer
(Li+) battery-pack protector ICs for 3- or 4-series Li+ bat-
tery packs. The MAX1894/MAX1924 enhance the useful
operating life of Li+ batteries by monitoring individual cell
voltages and preventing over/undervoltage conditions.
The MAX1894/MAX1924 also protect the battery pack
against charge current, discharge current, and pack-
short fault conditions.
In case of a fault condition, on-board drivers control
external P-channel MOSFETs, which disconnect the cells
from the pack external terminals. The external protection
MOSFETs are connected in a common-source configura-
tion that does not require external pullup resistors. The
MAX1894/MAX1924 use only one current-sense resistor
to achieve the protection features. All protection thresh-
olds and delays do not require any external components
and are trimmed at the factory.
If any cell voltage drops below the undervoltage thresh-
old, the MAX1894/MAX1924 disconnect the pack from
the load and power down to prevent deep discharge of
the pack. The MAX1894/MAX1924 offer a trickle-charge
feature, which provides a low-current path to safely
charge a deeply discharged pack. The MAX1894/
MAX1924 also have two logic-level inputs, which can be
used by a microcontroller to disable the protection
MOSFETs and to put the device in shutdown. The
MAX1894/MAX1924 have low quiescent current (30µA
typ) and ultra-low shutdown current (0.8µA typ) to pre-
vent deep-cell discharge.
The MAX1894X is designed for 4-series battery packs,
without hysteresis on the protection thresholds. The
MAX1924V and MAX1924X include hysteresis for the 3-
and 4-series packs, respectively.
Applications3- or 4-Series Li+ Battery Packs
FeaturesProtect Against Cell Overvoltage
Factory Programmable Limits from 4V to 4.4V
Accurate to ±0.5% Protect Against Cell Undervoltage
Factory Programmable Limits from 2V to 3.2V
Accurate to ±2.0%Protect Against Charge, Discharge, and Pack-
Short Current Faults Automatically Trickle Charges Deeply Discharged
CellsFully Integrated MOSFET Drivers Do Not Require
Pullup Resistors0.8µA (typ) Shutdown Supply Current Prevents
Deep Discharge of Cells30µA (typ) Operating Supply Current 28V (max) Input Voltage Available in Small 16-Pin QSOP Package
MAX1894/MAX1924
Advanced Li+ Battery-Pack ProtectorsB4PSRC
SHDN
CTL
PKN
TOP VIEW
MAX1894
MAX1924
QSOPVCC
B3P
IC2
IC3
B2P
B1P
IC1
DSO
CGO
TKO
Pin Configuration19-2278; Rev 0; 4/02
Ordering Information
PARTTEMP RANGEPIN-PACKAGECELLSOVERVOLTAGEOVERVOLTAGE
THRESHOLD HYSTERESIS
MAX1894XEEE-40°C to +85°C16 QSOP44.25V*No
MAX1924VEEE-40°C to +85°C16 QSOP34.35V*Yes
MAX1924XEEE-40°C to +85°C16 QSOP44.35V*Yes
*Contact factory for alternative threshold voltages.
Typical Applications Circuits appear at end of data sheet.
MAX1894/MAX1924
Advanced Li+ Battery-Pack Protectors
ABSOLUTE MAXIMUM RATINGSStresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
SRC, IC2, IC3, VCCto BN.......................................-0.3V to +28V
IC1 to BN..................................................................-0.3V to +6V
DSO, TKO, CGOto BN.............................-0.3V to (VSRC+ 0.3V)
B4P to B3P...............................................................-0.3V to +6V
B3P to B2P...............................................................-0.3V to +6V
B2P to B1P...............................................................-0.3V to +6V
B1P to BN.................................................................-0.3V to +6V
CTL, SHDN to PKN...................................................-0.3V to +6V
PKN to BN...................................................................-2V to +2V
ESD Protection on All Pins...............................................±2000V
Continuous Power Dissipation (TA= +70°C)
16-Pin QSOP (derate 8.3mW/°C above +70°C)...........667mW
Operating Temperature Range...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
ELECTRICAL CHARACTERISTICS(VSRC= VB4P+ 0.1V, each battery cell voltage (VCELL)= 3.6V, VCTL= VSHDN= VPKN, TA
= 0°C to +85°C, unless otherwise noted.Typical values are at TA= +25°C.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSRC Input CurrentVSRC - VB_P = 1V2040µA
Supply Current (Note 1)ISUPNo faults3045µA
Shutdown Supply CurrentISHDNUndervoltage without charge source0.82µA
Top Cell Sampling Current
(Note 2)VCELL = 3.6V60µA
Intermediate Cell Input Bias
Current (Note 3)VCELL = 3.6V500pA
VCC Undervoltage Lockout
ThresholdRising edge, hysteresis = 1% falling edge4.5V
Charge-Mode Detection
ThresholdVSRC - VB4P25100mV
MAX1894X cell voltage rising4.2254.2504.275Overvoltage Threshold (Note 4)VOV_THMAX1924X, MAX1924V cell voltage rising4.3254.3504.375V
Overvoltage Threshold
HysteresisVOV_HYTMAX1924X, MAX1924V cell voltage falling200mV
Undervoltage Threshold (Note 4)VUV_THCell voltage falling2.2602.3002.340V
PKN to BN Discharge Current
Fault ThresholdVOD_TH130145160mV
PKN to BN Charge Current
Fault ThresholdVOC_TH-120-100-80mV
PKN to BN Discharge Current
Fault Threshold, Pack-Short
Condition
VPS_TH385405425mV
Discharge or Charge Current
Fault to DSO, CGO, TKO
Transition Delay Time
tI-DELAY2.533.5ms
Discharge Current Fault to DSO
Transition Time Delay for Pack-
Short Condition
tP-DELAY400450500µs
MAX1894/MAX1924
Advanced Li+ Battery-Pack Protectors
ELECTRICAL CHARACTERISTICS (continued)(VSRC= VB4P+ 0.1V, each battery cell voltage (VCELL) = 3.6V, VCTL= VSHDN= VPKN, TA
= 0°C to +85°C, unless otherwise noted.Typical values are at TA= +25°C.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSCharge-Voltage Comparator
Threshold for Resetting
Discharge-Current Fault Latch
VSRC - VB4P25100mV
Discharge-Voltage Comparator
Threshold for Resetting Charge-
Current Fault Latch
VB4P - VSRC25100mV
DSO, CGO, and TKO Sink
CurrentVSRC = 12V, VPIN = 5V (Note 5)100200µA
DSO, CGO, and TKO
Source Current
VSRC = 12V, VPIN = 10V
VCTL = 3V (Note 5)3.55mA
Under/Overvoltage to DSO,
CGO, TKO Transition DelaytV-DELAY270320370ms
SHDN, CTL Input High (Note 6)Rising edge2.4V
SHDN, CTL Input Low (Note 6)Falling edge1.2V
SHDN, CTL Input Leakage
CurrentPKN = BN1µA
SHDN, CTL Delay to Output
Change50ns
DSO, CGO, TKO Output High
(Note 7)VB_P = 4V, VCTL = 3V-0.1V
DSO, CGO, TKO Output Low
(Note 7)VB_P = 4V-14V
MAX1894/MAX1924
Advanced Li+ Battery-Pack Protectors
Note 1:Average current from the top of the battery pack. Measured at VCC.
Note 2:Typical supply current for the top cell during the 0.5ms sampling period.
Note 3:Input bias current for this measurement is valid when all cell voltages are equal and the measurement is made over a time
greater than 3 seconds.
Note 4:Each cell voltage is sampled individually and a differential measurement is made (VB4P- VB3P, VB3P- VB2P, VB2P- VB1P,
and VB1P- BN).
Note 5:VPINrepresents VDSO, VCGO, or VTKO.
Note 6:Inputs to SHDN and CTL pins are referred to PKN.
Note 7:Measurements are with respect to VSRC.
ELECTRICAL CHARACTERISTICS(VSRC= VB4P+ 0.1V, each battery cell voltage (VCELL) = 3.6V, VCTL= VSHDN= VPKN, TA
= -40°C to +85°C, unless otherwise noted.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSRC Input CurrentVSRC - VB_P = 1V40µA
Supply Current (Note 1)ISUPNo faults50µA
Shutdown Supply CurrentISHDNUndervoltage without charge source2µA
Charge-Mode Detection
ThresholdVSRC - VB4P25100mV
MAX1894X cell voltage rising4.214.29Overvoltage Threshold (Note 4)VOV_THMAX1924X, MAX1924V cell voltage rising4.324.38V
Undervoltage Threshold (Note 4)VUV_THCell voltage falling2.242.36V
PKN to BN Discharge-Current
Fault ThresholdVOD_TH120170mV
PKN to BN Charge-Current
Fault ThresholdVOC_TH-130-70mV
PKN to BN Discharge-Current
Fault Threshold, Pack Short
Condition
VPS_TH345465mV
Discharge- or Charge-Current
Fault to DSO, CGO, TKO
Transition Delay Time
tI-DELAY24ms
Discharge-Current Fault to DSO
Transition Time Delay for Pack
Short Condition
tP-DELAY370480µs
Charge-Voltage Comparator
Threshold for Resetting
Discharge-Current Fault Latch
VSRC - VB4P25100mV
Discharge-Voltage Comparator
Threshold for Resetting Charge-
Current Fault Latch
VB4P - VSRC25100mV
DSO, CGO, and TKO Sink
CurrentVSRC = 12V, VPIN = 5V (Note 5)100µA
DSO, CGO, and TKO
Source Current
VSRC = 12V, VPIN = 10V
VCTL = 3V (Note 5)3.5mA
Under/Overvoltage to DSO,
CGO, TKO Transition DelaytV-DELAY270370ms
SHDN, CTL Input High (Note 6)Rising edge2.4V
SHDN, CTL Input Low (Note 6)Falling edge1.2V
MAX1894/MAX1924
Advanced Li+ Battery-Pack Protectors
Typical Operating Characteristics(TA = +25°C, unless otherwise noted.)
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX1894 toc01
TEMPERATURE (°C)
SUPPLY CURRENT (4-SERIES BATTERY PACK
SUPPLY CURRENT
vs. TEMPERATUREMAX1894 toc02
TEMPERATURE (°C)
SUPPLY CURRENT (3510-15
4-SERIES BATTERY PACK
UNDERVOLTAGE THRESHOLD
vs. TEMPERATURE
MAX1894 toc03
TEMPERATURE (°C)
CELL VOLTAGE (V)
B1P
B4P
B2P
B3P
OVERVOLTAGE THRESHOLD
vs. TEMPERATURE
MAX1894 toc04
TEMPERATURE (°C)
CELL VOLTAGE (V)
B1P
B2P
B4P
B3P
MAX1924X
CHARGE-CURRENT FAULT
THRESHOLD vs. TEMPERATURE
MAX1894 toc05
TEMPERATURE (°C)
BN
- V
PKN
(mV)-153560
CHARGE-CURRENT FAULT RECOVERY
THRESHOLD vs. TEMPERATUREMAX1894 toc06
TEMPERATURE (°C)
B4P
- V
SRC
(mV)35-1510
DISCHARGE-CURRENT FAULT THRESHOLD
vs. TEMPERATURE
MAX1894 toc07
TEMPERATURE (°C)
PKN
- V
(mV)3510-15
DISCHARGE-CURRENT FAULT RECOVERY
THRESHOLD vs. TEMPERATURE
MAX1894 toc08
TEMPERATURE (°C)
B4P
- V
SRC
(mV)
PACK-SHORT CURRENT FAULT
THRESHOLD vs. TEMPERATURE
MAX1894 toc09
TEMPERATURE (°C)
PKN
- V
(mV)
MAX1894/MAX1924
Advanced Li+ Battery-Pack Protectors
PINNAMEFUNCTIONB4PCell 4 Positive Connection. Short B4P to B3P for MAX1924V.
2VCCSupply Input. Connect this pin to the top of the battery pack through a diode and a capacitor
(see the Typical Application Circuit).B3PCell 3 Positive ConnectionIC3Internal Connection. Float this pin.B2PCell 2 Positive ConnectionIC2Internal Connection. Float this pin.B1PCell 1 Positive ConnectionIC1Internal Connection. Float this pin.
9BNBattery Negative. Connection for the cell 1 negative terminal and the top of the current-sense
resistor RSENSE. BN is also chip ground.PKNPack Negative. The sense resistor (RSENSE) is connected between BN and PKN.CTLControl Input. Drive CTL low for normal operation. Drive CTL high to turn off the three external
protection MOSFETs.SHDNShutdown. Drive SHDN low for normal operation. Drive SHDN high to put the device into shutdown
if no charger is present.TKOTrickle-Charge Driver Output. TKO drives the gate of an external P-channel trickle-charge MOSFET
low (on) in normal operation.CGOFast-Charge Driver Output. CGO drives the gate of an external P-channel fast-charge MOSFET low
(on) in normal operation.DSODischarge Driver Output. DSO drives the gate of an external P-channel discharge control MOSFET
low (on) in normal operation.SRCCommon Source Connection for MOSFETs. SRC provides the bias for gate drivers DSO, TKO,
and CGO.
Pin Description
DISCHARGE-CURRENT FAULT TIMINGMAX1894 toc10
VPKN - VBN
100mV/div
DSO
5V/div
1ms/div
CHARGE-CURRENT FAULT TIMINGMAX1894 toc11
VPKN - VBN
100mV/div
1ms/div
CGO
5V/div
PACK-SHORT CURRENT FAULT TIMINGMAX1894 toc12
VPKN - VBN
200mV/div
100μs/div
DSO
5V/div
Typical Operating Characteristics (continued)(TA = +25°C, unless otherwise noted.)
MAX1894/MAX1924
Advanced Li+ Battery-Pack Protectors
Detailed DescriptionThe MAX1894/MAX1924 battery-pack protectors super-
vise the charging and discharging process of Li+ cells.
Designed for 3-series (MAX1924V) and 4-series
(MAX1894X/MAX1924X) applications, these devices
monitor the voltage across each cell to provide protec-
tion against undervoltage, overvoltage, and
overcurrent damage.
Output pins CGO, TKO, and DSOcontrol external
MOSFET gates. These MOSFETs, in turn, control the
fast-charging, trickle-charging, and discharge process-
es of the battery pack (Figure 1).
Modes of Operation
Shutdown ModeThe MAX1894/MAX1924 go into shutdown mode under
two conditions: the SHDN pin is driven high without a
charger applied, or a battery cell undervoltage fault is
detected, also without a charger applied. In shutdown
mode, the device consumes 0.8µA (typ) on the VCCpin
and all MOSFETs are off. The MAX1894/MAX1924 stay
in shutdown mode as long as no charging voltage is
applied to the battery pack (VSRCis less than the pack
voltage). When the battery pack is connected to a
charger (VSRC> VB4P+ 0.1V) and the pack voltage is
above 4.5V, the device goes into normal operating
mode and begins monitoring the pack (see Figure 2).
Normal ModeIn the normal mode of operation, the MAX1894/MAX1924
are in either a standby mode (29µA typ) or sample mode
(160µA typ). The device enters the standby mode from
shutdown mode. The standby mode lasts for 79ms; then
the device goes into the sample mode. During sample
mode, the MAX1894/MAX1924 check each cell for over-
voltage and undervoltage. Sample mode lasts for 0.5ms;
then the MAX1894/MAX1924 return to standby mode.
During sample mode, the MAX1894/MAX1924 do not intro-
duce cell mismatch.
During normal mode operation, the MAX1894/MAX1924
continuously monitor the voltage across RSENSEfor charge
or discharge current faults, or battery pack-short faults.
Protection Features
Overvoltage ProtectionThe MAX1894/MAX1924 provide overvoltage protection
to avoid overcharging cells. When an overvoltage fault
is detected in four consecutive samples, CGOand TKO
go high, stopping the charging process. The
MAX1894/MAX1924 continue to sample the cell volt-
ages, and if no overvoltage is detected, CGOand TKO
are returned to the normal low state (see Figure 3). The
MAX1924 also includes a hysteresis of 200mV.
The overvoltage threshold is preprogrammed and
requires no external components. The overvoltage thresh-
old is factory set at 4.25V (typ) for the MAX1894 and
4.35V (typ) for the MAX1924. Contact Maxim for more
information on threshold levels between 4V and 4.4V.
Undervoltage ProtectionThe MAX1894/MAX1924 provide undervoltage protec-
tion to avoid overdischarging the cells. With no battery
charger present, and an undervoltage fault is detected
in four consecutive samples, DSO, CGO, and TKOgo
high and the device goes into shutdown mode (see
Figure 4).
If a battery charger is applied to the battery pack and
one or more cells are below VUV_TH, then only TKO
goes low, allowing trickle-charge current to flow. If no
undervoltage is detected in any sample, DSO, CGO,
and TKOall go low.
The undervoltage threshold is preprogrammed at 2.30V
(typ). Contact Maxim for more information on threshold
levels between 2V and 3.2V.
Charge-Current Fault ProtectionThe MAX1894/MAX1924 protect against excessive
charge current by monitoring the voltage developed
across RSENSE. RSENSEis connected between BN and
PKN. If VRSENSEexceeds the charge-current fault
threshold (VOC_TH, typically 100mV) for more than 3ms,
the charge current comparator is tripped, setting CGO
and TKOhigh.
The charge-current fault condition is latched and is not
reset until the MAX1894/MAX1924 detect a reversal in
SYMBOLDESCRIPTIONVOC_THCharge-Current Fault Threshold
(Negative Value)
VOD_THDischarge-Current Fault Threshold
VPS_THPack-Short Discharge-Current Fault
Threshold
VUV_THUndervoltage Threshold
VOV_THOvervoltage Threshold
VSRCMOSFET Common Source Voltage
VRSENSESense Resistor Voltage
VOV_HYTOvervoltage Threshold Hysteresis
OVFOvervoltage Sample Counter
UVFUndervoltage Sample Counter
Table 1. Flow Chart Symbol Table
MAX1894/MAX1924
Advanced Li+ Battery-Pack Protectorsthe direction of current flow. To reverse the current flow,
the charger has to be removed (Figure 5). The sustain-
ing condition for the latch is a 100mV (max) voltage
drop across SRC and B4P. Since the charge-current
fault threshold between BN and PKN is also 100mV
(typ), the RDS_ONof the overcharge protection MOSFET
must be greater than the sense resistor in order to
ensure a latched state.
Discharge-Current Fault ProtectionThe MAX1894/MAX1924 protect against excessive dis-
charge-current by monitoring the voltage developed
across RSENSE. If VRSENSEexceeds the discharge-cur-
rent fault threshold (VOD_TH, typically 145mV) for more
than 3ms, the discharge-current comparator is tripped,
setting DSO, CGO, and TKOhigh.
Discharge-current fault is latched and is not reset until
the MAX1894/MAX1924 detect a reversal in the direc-
tion of current flow. To reverse the current flow, a
charger must be applied (Figure 6).
Pack-Short Current Fault ProtectionThe MAX1894/MAX1924 protect against a shorted
pack by monitoring the voltage developed across
RSENSE. If VRSENSEexceeds the pack-short threshold
(VPS_TH, typically 405mV) for more than 450µs, the
pack-short comparator is tripped, setting CGO, DSO,
and TKOhigh.
DSO15
TKO13
B4P1
SRC
51Ω
RTKO
510Ω
1kΩ
1μF
0.1μF
10Ω
0.1μF
0.1μF
0.1μF
1kΩ
1kΩ
VCC
B3P3
IC34
B2P5
IC26
B1P7
IC189
PKN
CGO
MICRO-
CONTROLLER
SHDN
CTLRSENSE
0.02Ω
PACK +
PACK -
OVERDISCHARGE
PROTECTION
OVERCHARGE
PROTECTION
CMPSH-3
TRICKLE
CHARGE
MAX1894X
MAX1924X
2.2μF
Figure 1. Typical Applications Circuit with Trickle Charge
