JAJSHI6G June 2018 – July 2021 TPS25830-Q1 , TPS25831-Q1
PRODUCTION DATA
When a load draws current through a long or thin wire, there is an IR drop that reduces the voltage delivered to the load. Cable droop compensation linearly increases the voltage at the CSN/OUT pin of TPS2583x-Q1 as load current increases with the objective of maintaining VBUS_CON (the bus voltage at the USB connector) at 5 V, regardless of load conditions. Most portable devices charge at maximum current when 5 V is present at the USB connector. Figure 10-22 provides an example of resistor drops encountered when designing an automotive USB system with a remote USB connector location.
The TPS2583x-Q1 detects the load current and increases the voltage at the CSN/OUT pin to compensate the IR drop in the charging path according to the gain set by the RSNS, RSET, and RIMON resistors as described in RSNS, RSET, RILIMIT, and RIMON.
The amount of cable droop compensation required can be estimated by the following equation ΔVOUT = (RSNS + RDSON_NFET + RWIRE) × IBUS. RIMON is then chosen by RIMON = (ΔVOUT × RSET × 2) / (IBUS × RSNS), where ΔVOUT is the desired cable droop compensation voltage at full load.
Per RSNS, RSET, RILIMIT, and RIMON, in most cases, the recommended voltage across RSNS should be 50 mV. In type-C application, typical RIMON resistors value are listed in Table 10-3 given the condition full load current = 3 A, RSNS = 15 mΩ and RSET = 300 Ω.
Cable Compensation Voltage at 3-A Full Load (V) | RIMON (kΩ) | |
---|---|---|
0.3 | 4.02 | |
0.6 | 8.06 | |
0.9 | 12.1 | |
1.2 | 16.2 | |
1.5 | 20 |
Pls be noted that the max cable compensation voltage in TPS2583x-Q1 is 1.5 V.