JAJSL03C January 2021 – December 2021 TPS61094
PRODUCTION DATA
When the TPS61094 is enabled working in Buck mode (EN = high, MODE = low), the TPS61094 works in constant output current control scheme with the bypass switch always turned on. The TPS61094 supports sixteen internally set options for the charging termination voltage (VCHG) and charging current (ICHG) by connecting a resistor between the VCHG pin, ICHG pin, and ground.
When VOUT voltage is above the 1.7-V UVLO rising threshold, the buck function starts working to charge the supercap at the SUP pin. The typical charging operation (VCHG < VIN-800 mV) works as shown in Figure 7-1. At t0, the TPS61094 starts to charge the SUP pin by constant current. From t0 to t1, when the SUP pin voltage is lower than VSUP_UVLO, typically 0.85 V, the TPS61094 charges the SUP pin by the constant current (ICHG_PRE), which is smaller than or equal to 250 mA. From t1 to t2, when the SUP pin voltage reaches VSUP_UVLO, the TPS61094 charges the SUP pin by constant current (ICHG), which is set by the ICHG pin. At t2, the SUP pin voltage reaches VCHG (charging termination voltage) and the TPS61094 reduces the charging current to ICHG_TERM, the device stops switching until the SUP voltage reaches VCHG without the supercap ESR voltage drop. This can be avoided if the supercap is not fully charged when the SUP pin reaches VCHG in high charging current because of supercap ESR voltage drop. The TPS61094 starts switching when the SUP voltage drops 75 mV below the target value (VCHG).
If VCHG > VIN-500 mV, the TPS61094 will decrease the charging current when the SUP pin voltage is close to VIN.