Nisshinbo Micro Devices NB7120

The NB7120ZA is a state-of-the-art single-cell Li-Ion battery protection IC in an ultra-small WLCSP package with advanced features and additional safety measures, ideal for a wide range of applications, including hearing aids and wearable devices, smartphones, and handheld data terminals. The NB7120 is an exceptional protection IC equipped with all standard safety features, such as overcharge/over-discharge voltage, charge/discharge overcurrent and short circuit detection, making the application highly reliable. The additional safety measures are mainly focussed on the improved accuracy level of these measurements, which is particularly important for small devices worn on or in the human body to prevent unintentional injuries when the Li-Ion battery fails, such as: • High-accuracy overcharge and over-discharge detection (OVP & UVP) Both support extending battery life as the battery voltage can be nearer to the threshold level • High-accuracy overcurrent detection (OCP) A lower sense voltage and more accurate overcurrent detection enables the use of a smaller (Rsense) sense resistor, resulting in a lower heat generation at high currents • High-accuracy 0 V Battery Charging Inhibition Voltage Charging a deep discharged battery (0 V) can cause an internal short circuit, the inhibition threshold voltage can be set in a 0.05 V step rate from a safety point of view • A TIN pin was added to connect a temperature sensor and monitor the temperature of the battery cell. A unique feature of the NB7120 is the use of high-side MOSFETs which allow the ground of the protection circuit to be connected directly to the battery's negative terminal. This simplifies the design complexity as all measurement and control signals can be referenced to the same ground potential. While using high-side MOSFETs offers advantages, they typically require a more complex gate control circuitry, as the gate voltage must be higher than the source voltage. Therefore, a dedicated charge pump is integrated, and no additional external components are required. Finally, the additional CTL input offers a Forced Standby Function to control the product into standby mode without over-discharging the battery. Power consumption can be significantly reduced in this way and returns to the normal mode when a charger is connected.

Key features

• Supply current: Normal mode: Typ. 5.0μA / Max. 8.0 μA, Standby mode: Max. 0.04 μA
• Overcharge Detection Voltage (V_DET1): 4.2 V to 4.6 V, ±10 mV
• Over-discharge Detection Voltage (V_DET2): 2.0 V to 3.4 V, ±35 mV
• Discharge Overcurrent Detection Voltage (V_DET3): 0.0080 V to 0.030 V: ±1.5 mV, 0.0301 V to 0.060V: ±5％, 0.0601 V to 0.0800 V: ±3 mV
• Charge Overcurrent Detection Voltage (V_DET4): –0.008 V to –0.0325 V: ±1.5 mV, –0.0326 V to –0.0600 V: ±5%, –0.0601 V to –0.0800 V: ± 3mV
• Short Circuit Detection Voltage (V_SHORT): 0.025 V to 0.125 V, ±2.5 mV
• 0 V Battery Charging: Inhibition
• 0 V Battery Charging Inhibition Voltage (V_NOCHG): 1.25 V to 2.00 V, ±50 mV
• Over-discharge release type: Latch
• Discharge overcurrent release type options: Auto release / Latch
• NB7120ZA package: WLCSP-8-P15

Applications

• Hearing aids
• Wearable devices
• Smart phone
• Handheld data terminals