Electronic Components Datasheet Search |
|
MAX712CPE Datasheet(PDF) 11 Page - Maxim Integrated Products |
|
MAX712CPE Datasheet(HTML) 11 Page - Maxim Integrated Products |
11 / 17 page NiCd/NiMH Battery Fast-Charge Controllers ______________________________________________________________________________________ 11 Nonstandard Trickle-Charge Current Example Configuration: Typical Operating Circuit 2 x Panasonic P-50AA 500mAh AA NiCd batteries C/3 fast-charge rate 264-minute timeout Negative voltage-slope cutoff enabled Minimum DC IN voltage of 6V Settings: Use MAX713 PGM0 = V+, PGM1 = open, PGM2 = BATT-, PGM3 = BATT-, RSENSE = 1.5 Ω (fast-charge current, IFAST = 167mA), R1 = (6V - 5V)/5mA = 200 Ω Since PGM3 = BATT-, the voltage on RSENSE is regulat- ed to 31.3mV during trickle charge, and the current is 20.7mA. Thus the trickle current is actually C/25, not C/16. Further Reduction of Trickle-Charge Current for NiMH Batteries The trickle-charge current can be reduced to less than C/16 using the circuit in Figure 7. In trickle charge, some of the current will be shunted around the battery, since Q2 is turned on. Select the value of R7 as follows: R7 = (VBATT + 0.4V)/(lTRlCKLE - IBATT) where VBATT = battery voltage when charged ITRlCKLE = MAX712/MAX713 trickle-charge current setting IBATT = desired battery trickle-charge current Regulation Loop The regulation loop controls the output voltage between the BATT+ and BATT- terminals and the current through the battery via the voltage between BATT- and GND. The sink current from DRV is reduced when the output voltage exceeds the number of cells times VLIMIT, or when the battery current exceeds the pro- grammed charging current. For a linear-mode circuit, this loop provides the following functions: 1) When the charger is powered, the battery can be removed without interrupting power to the load. 2) If the load is connected as shown in the Typical Operating Circuit, the battery current is regulated regardless of the load current (provided the input power source can supply both). Voltage Loop The voltage loop sets the maximum output voltage between BATT+ and BATT-. If VLIMIT is set to less than 2.5V, then: Maximum BATT+ voltage (referred to BATT-) = VLIMIT x (number of cells as determined by PGM0, PGM1) VLIMIT should be set between 1.9V and 2.5V. If VLIMIT is set below the maximum cell voltage, proper termination of the fast-charge cycle might not occur. Cell voltage can approach 1.9V/cell, under fast charge, in some battery packs. Tie VLIMIT to VREF for normal operation. With the battery removed, the MAX712/MAX713 do not provide constant current; they regulate BATT+ to the maximum voltage as determined above. OPEN 2C IFAST/32 FAST-CHARGE RATE TRICKLE-CHARGE CURRENT (ITRICKLE) V+ 4C IFAST/64 BATT- C/2 IFAST/8 PGM3 REF C IFAST/16 Table 5. Trickle-Charge Current Determination from PGM3 FASTCHG RSENSE BATTERY R7 Q2 10k V+ 10k DRV D1 Q1 DC IN GND MAX712 MAX713 Figure 7. Reduction of Trickle Current for NiMH Batteries (Linear Mode) |
Similar Part No. - MAX712CPE |
|
Similar Description - MAX712CPE |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |