The LTC ® 3337 is a primary battery state of health (SOH) monitor with a built-in precision coulomb counter . It is designed to be placed in series with a primary battery with minimal associated series voltage drop. The patented infinite dynamic range coulomb counter tallies ALL accumulated battery discharge and stores it in an internal register accessible via an I 2 C interface. A discharge alarm threshold based on this state of charge (SOC) is programmable. When it is reached, an interrupt is generated at the IRQ pin. Coulomb counter accuracy is constant down to no load.

The LTC3337 also integrates additional SOH monitoring which measures and reports via I 2 C: battery voltage, battery impedance, and temperature.

To accommodate a wide range of primary battery inputs, the peak input current limit is pin selectable from 5mA to 100mA.

Coulombs can be calculated for either the BAT_IN or BAT_OUT pin, determined by the AV CC pin connection.

A BAL pin is provided for applications utilizing a stack of two supercapacitors (optional) at the output.

The LTC3337 is offered in both 12-lead 2mm × 2mm LFCSP and 16-ball 1.64mm × 1.64mm WLCSP packages.

All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. patents, including 9312815.

• n Battery Input Voltage Range: 1.8V to 5.5V
• n 100nA Quiescent Current
• n 8 Primary Battery Peak Input Current Limits: 5mA/10mA/15mA/20mA/25mA/50mA/75mA/100mA
• n SOH Monitor for Primary Battery
• n Integrated Coulomb Counter (Q)
• n Additional Monitors for Battery Voltage (V), Battery Impedance (Z), and Temperature (T)
• n Primary Battery Current (BAT_IN) or Load Current (BAT_OUT) is Counted
• n Integrated ±10mA Supercapacitor Balancer
• n Programmable Coulomb Counter Prescaler for Wide Range of Battery Sizes
• n Programmable Discharge Alarm Threshold with Interrupt Output
• n I 2 C Interface
• n Tiny 12-Lead 2mm × 2mm LFCSP and 16-Ball 1.64mm × 1.64mm WLCSP Packages

• n Low Power Primary Battery Powered Systems (e.g., 1× LiSOCl 2 , 2-3× Alkaline)
• n Remote Industrial Sensors (e.g., Meters, Alarms)
• n Asset T rackers
• n Electronic Door Locks
• n Keep-Alive Supplies/Battery Backup
• n SmartMesh ® Applications

LTC3337 Pinout

Package: LFCSP 12-Lead QFN (2mm × 2mm × 0.75mm)

Notes

• Pin 13 is an exposed pad (thermal/ground pad) on the bottom of the package and must be soldered to PCB.
• AVCC and DVCC are separate supply pins and should be properly decoupled.
• IPK0, IPK1, IPK2 form a 3-bit input for peak current selection.
• SCL and SDA are I²C interface pins.

The l denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at T A = 25°C. (Note 2). BAT_IN = BAT_OUT = AV CC = DV CC = 3.6V unless otherwise noted.

Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime.

Note 2: The LTC3337 is specified over the -40°C to 125°C operating junction temperature range. High junction temperatures degrade operating lifetimes. Note the maximum ambient temperature consistent with these specifications is determined by specific operating conditions in conjunction with board layout, the rated package thermal impedance and other environmental factors.

Note 3: T J is calculated from the ambient T A and power dissipation P D according to the following formula: T J = T A + (P D · θ JA ).

Note 4: Coulomb counter and peak current limit accuracy are at their best for BAT_IN voltages above 2V. Voltage and Temperature Monitor accuracy are at their best down to 1.8V. See Extended Battery Range Below 2V in the Operation section.

BAT_IN, BAT_OUT, AV CC  Voltage  .................. -0.3V to 6V (BAT_OUT - BAT_IN) Differential Voltage ................0.3V DVCC , SCL, SDA Voltage .............................. -0.3V to 6V IPK[2:0] Voltage  ................................-0.3V to [Lesser of (BAT_IN + 0.3V) or 6V] BAL Voltage ......................................-0.3V to [Lesser of (BAT_OUT + 0.3V) or 6V]