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ACT2861QI 数据表(PDF) 36 Page - Active-Semi, Inc |
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ACT2861QI 数据表(HTML) 36 Page - Active-Semi, Inc |
36 / 91 page ACT2861QI Rev 2.0, 27-Apr-2018 Innovative PowerTM www.active-semi.com ActiveSwitcherTM is a trademark of Active-Semi Copyright © 2018 Active-Semi, Inc. 36 Table 4: Charge Current Component Selection Switching Frequency = 125kHz IOLIM (A) RCS (mΩ) ROLIM (kΩ) RCS_COMP (kΩ) CCS_COMP (nF) 5 10 20 NA NA 4 10 25 NA NA 3 10 33 10 330 2 10 50 10 330 1.5 20 33 10 330 1 20 50 10 330 Switching Frequency = 250kHz, 500kHz, 1MHz IOLIM (A) RCS (mΩ) ROLIM (kΩ) RCS_COMP (kΩ) CCS_COMP (nF) 5 10 20 NA NA 4 10 25 NA NA 3 10 33 NA NA 2 10 50 15 56 1.5 20 33 10 100 1 20 50 10 100 To eliminate noise in the current measurement circuit, the current sense voltage must be filtered. The recom- mended values are ROSRP = ROSRN = 30.1ohm and COSR = 100nF. These values can be scaled up or down, but ROSRP must be between 20ohm and 50ohm, and the re- sulting filter cutoff frequency must be between 20kHz and 30kHz. The actual charge current can be measured with the OLIM pin. The OLIM voltage is directly proportional to the charging current. The following equation calculates the charging current. 2 Where IOLIM is the hardware programmed 100% charg- ing current in amps and VOLIM is the voltage measured at the OLIM pin. Note that the output current in charge mode becomes the input current in OTG mode. Charging – Dead Battery, Short Circuit, and Precharge Currents The charger operates at reduced currents when the battery voltage is low. This protects the battery chemistry and prepares it for fast charging. When in the SCOND_DB mode, the charger supplies a fixed 10mA of charge current. When in the SCOND mode, the charger supplies the “short battery” current, ISHRT. ISHRT is a fixed percentage of ICHG which is set by the I2C bits VBAT_SHORT_CURRENT in register 0x0Bh. When in the PCOND mode (precharge), the charger supplies the “precharge” current, IPRECHG. IPRECHG is a fixed percentage of ICHG which is set by the I2C bits IPRECHG in register 0x19h. IPRECHG can set the pre- charge current from 5% to 20% of the ICHG. Charging - Maximum Input Current Limit In Charge mode, the IC features an input current limit circuit to meet maximum input current limitations for USB sources and to avoid over loading weak input volt- age sources. Figure 12 shows that the input current lim- iting circuitry is identical to the charge current setting circuitry. When the input current reaches current limit, the ACT2861 control circuitry starts regulating the max- imum input current. When in charge mode, this effec- tively lowers the charge current to maintain the maxi- mum programmed input current. The maximum allowa- ble input current is 5A. The actual input current limit, IIN_LIM can be scaled from 1% to 100% of IILIM in 1% steps. The following equation defines the final input current limit. _ ∗ 6: 0 Where IILIM is the hardware programmed current limit and INLIM[6:0] is the scaling factor. INLIM[6:0] is the decimal equivalent value in this register. For example, if IILIM, is programmed to 5A and INLIM[6:0] = 0111100b (60% decimal), the final charge current = 5A * 0.60 = 3A. Note that INLIM[6:0] is a 7 bit register and can be pro- grammed between 0x00h and 0x7Fh (0% and 127%). If a value of 0x00h is written to the register, the register retains 0x00h, but the IC sets the input current to 1%. If a value above 0x64h (100%) is written to the register, the IC retains the written value, but sets the input cur- rent to 100%. Input current limit can be set by the ILIM pin and IINLIM[6:0] registers. |
类似零件编号 - ACT2861QI |
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类似说明 - ACT2861QI |
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