MAX1924XEEE ,Advanced Li+ Battery-Pack Protectorsfeatures. All protection thresh- 0.8µA (typ) Shutdown Supply Current Preventsolds and delays do no ..
MAX1924XEEE ,Advanced Li+ Battery-Pack ProtectorsApplications Circuits appear at end of data sheet.____ Maxim Integrated Products 1For pricing, deli ..
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 ..
MAX488EEPA ,15kV ESD-Protected / Slew-Rate-Limited / Low-Power / RS-485/RS-422 Transceiversapplications that are not ESD sen-MAX481ECPA 0°C to +70°C 8 Plastic DIPsitive see the pin- and func ..
MAX488EEPA+ ,±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 ,15kV ESD-Protected / Slew-Rate-Limited / Low-Power / RS-485/RS-422 Transceiversapplications that are not ESD sen-MAX481ECPA 0°C to +70°C 8 Plastic DIPsitive see the pin- and func ..
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 ..
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 Protectors
Pin Configuration19-2278; Rev 0; 4/02
Ordering Information*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.
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.
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
MAX1894/MAX1924
Advanced Li+ Battery-Pack Protectors
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
MAX1894/MAX1924
Advanced Li+ Battery-Pack Protectors
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
MAX1894/MAX1924
Advanced Li+ Battery-Pack Protectors
Detailed Description
The 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 Mode
The 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 Mode
In 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 Protection
The 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 Protection
The 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 Protection
The 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
MAX1894/MAX1924
Advanced Li+ Battery-Pack Protectors
the 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 Protection
The 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 Protection
The 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.
Figure 1. Typical Applications Circuit with Trickle Charge
