LTC3337

Part: LTC3337 — Analog Devices (Linear Technology)

Type: Primary Battery State-of-Health Monitor with Coulomb Counter

Description: 1.8–5.5 V primary battery SOH monitor with a precision coulomb counter, 100 nA quiescent current, pin-selectable 5–100 mA peak input current limit, and an I²C interface.

Operating Conditions:

• Supply voltage (BAT_IN, AVCC, DVCC): 1.8–5.5 V
• Operating junction temperature: -40 to 125 °C
• Peak input current limit: 5/10/15/20/25/50/75/100 mA, pin selectable
• Coulomb counter and peak current limit accuracy are best for BAT_IN above 2 V
• I²C clock: up to 400 kHz

Absolute Maximum Ratings:

• BAT_IN, BAT_OUT, AVCC voltage: -0.3 to 6 V
• DVCC, SCL, SDA voltage: -0.3 to 6 V
• BAT_OUT current: 150 mA
• IRQ, BATOUT_OK current: ±1 mA
• SDA current: 5 mA
• Operating junction temperature: -40 to 125 °C
• Storage temperature: -65 to 150 °C
• Maximum reflow (package body) temperature: 260 °C

Key Specs:

• AVCC quiescent current (BAT_IN - BAT_OUT = 50 mV): 100 nA typ, 160 nA max
• Peak input current (100 mA setting, BAT_IN - BAT_OUT = 175 mV): 100 mA typ, 90–110 mA at 25 °C
• Total coulomb counter error: ±3 % (production tested at the 100 mA setting)
• Voltage monitor: 1.465 mV LSB, total error ±1.0 % (±2.5 % over the full junction temperature range), full scale 6 V
• Temperature monitor: 0.784 °C LSB, range -41 to 159 °C
• Supercapacitor balancer: ±10 mA source/sink, balance point 50 % of BAT_OUT (49–51 %), input range 2.5–5.5 V, 62 nA typ quiescent current
• Full-scale coulomb count: 977.3 A·hr typ (100 mA setting, M=0); 1.491 mA·hr (5 mA setting, M=15)
• BATOUT_OK threshold (BAT_IN - BAT_OUT): 110 mV typ rising, 400 mV typ falling

Features:

• SOH monitor for primary batteries
• Integrated coulomb counter that counts either BAT_IN or BAT_OUT current, selected by the AVCC pin connection
• Additional monitors for battery voltage, battery impedance, and temperature
• Programmable coulomb counter prescaler for a wide range of battery sizes
• Programmable discharge alarm threshold with IRQ interrupt output
• Integrated ±10 mA supercapacitor balancer
• I²C interface

Applications:

• Low power primary battery powered systems (e.g., 1× LiSOCl₂, 2–3× alkaline)
• Remote industrial sensors (meters, alarms)
• Asset trackers
• Electronic door locks
• Keep-alive supplies and battery backup
• SmartMesh applications

Package:

• 12-Lead LFCSP, 2 mm × 2 mm × 0.75 mm (LTC3337ERC)
• 16-Ball WLCSP, 1.64 mm × 1.64 mm × 0.47 mm (LTC3337ACBZ)

• 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

LFCSP PACKAGE 12-LEAD (2mm × 2mm × 0.75mm) PLASTIC QFN T JMAX = 125°C, θ JA = 52.78°C/W EXPOSED PAD (PIN 13) IS GND, MUST BE SOLDERED TO PCB

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]

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.