ZHCSJ38C December 2018 – August 2019 TPS3840
PRODUCTION DATA.
This design requires voltage and temperature supervision on a battery voltage rail and the requirements may differ depending on if undervoltage or overvoltage monitoring is required. For this design, both requirements are considered to show the flexibility of the TPS3840 device. The first application example shown in Figure 49 uses TPS3840DL30, an open-drain active-low voltage supervisor to monitoring undervoltage and TMP303, a push-pull active-high window temperature switch to monitor under and over temperature. For the undervoltage application, the TPS3840DL30 is operating in the inactive logic high region so an overvoltage fault occurs when the battery voltage falls below VIT- = 3.0 V or when the battery temperature is outside the range from 0°C to 60°C. The second application example uses TPS3840DL30 operating in the active-low region to monitor overvoltage and TMP303 to monitor under and over temperature. For the overvoltage requirement, the fault occurs when the battery voltage rises above 3.1 V or when the battery temperature is outside the range from 0°C to 60°C.
| PARAMETER | DESIGN REQUIREMENT | DESIGN RESULT |
|---|---|---|
| Battery Voltage Supervision | Monitor 3.3-V battery for undervoltage condition | TPS3840 provides voltage monitoring with 1% accuracy with device options available in 0.1 V variations. TPS3840DL30 triggers a reset when VDD falls below 3 V. TPS3840PH30 triggers a reset when VDD rises above 3 V plus hysteresis setting the overvoltage threshold to 3.1 V. |
| Monitor 2.8-V battery for overvoltage condition | ||
| Battery Temperature Supervision | Monitor battery temperature between 0°C and 60°C with 1°C resolution for undervoltage design | TMP303A monitors temperature within 0°C to 60°C with 1°C resolution. Note this is a push-pull, active-high output device. |
| Output Topology | Undervoltage: Active-Low, Open-Drain | TPS3840 is offered in Active-Low Open-drain, Active-Low Push-Pull, and Active-High Push-Pull topologies |
| Overvoltage: Active-High, Push-Pull | ||
| Maximum device current consumption | 10 µA | TPS3840 requires 350 nA (typical) and TMP303 requires 3.5 µA (typical) |
| Delay when returning from fault condition | Delay of at least 6 seconds when returning from the fault to prevent operation in fault conditions | CCT = 10 µF sets 6.18 second delay |