Electronic Components Datasheet Search |
|
MAX712 Datasheet(PDF) 10 Page - Maxim Integrated Products |
|
MAX712 Datasheet(HTML) 10 Page - Maxim Integrated Products |
10 / 17 page NiCd/NiMH Battery Fast-Charge Controllers 10 ______________________________________________________________________________________ Operating Circuit), the diode (D1), and the sense resistor (RSENSE). This minimum input voltage require- ment is critical, because violating it can inhibit proper termination of the fast-charge cycle. A safe rule of thumb is to choose a source that has a minimum input voltage = 1.5V + (1.9V x the maximum number of cells to be charged). When the input voltage at DC IN drops below the 1.5V + (1.9V x number of cells), the part oscillates between fast charge and trickle charge and might never completely terminate fast-charge. The MAX712/MAX713 are inactive without the wall cube attached, drawing 5µA (max) from the battery. Diode D1 prevents current conduction into the DRV pin. When the wall cube is connected, it charges C1 through R1 (see Typical Operating Circuit) or the current-limiting diode (Figure 19). Once C1 charges to 5V, the internal shunt regulator sinks current to regulate V+ to 5V, and fast charge commences. The MAX712/MAX713 fast charge until one of the three fast-charge terminating conditions is triggered. If DC IN exceeds 20V, add a cascode connection in series with the DRV pin as shown in Figure 5 to prevent exceeding DRV’s absolute maximum ratings. Select the current-limiting component (R1 or D4) to pass at least 5mA at the minimum DC IN voltage (see step 6 in the Getting Started section). The maximum current into V+ determines power dissipation in the MAX712/MAX713. maximum current into V+ = (maximum DC IN voltage - 5V)/R1 power dissipation due to shunt regulator = 5V x (maximum current into V+) Sink current into the DRV pin also causes power dissipa- tion. Do not allow the total power dissipation to exceed the specifications shown in the Absolute Maximum Ratings. Fast Charge The MAX712/MAX713 enter the fast-charge state under one of the following conditions: 1) Upon application of power (batteries already installed), with battery current detection (i.e., GND voltage is less than BATT- voltage), and TEMP higher than TLO and less than THI and cell voltage higher than the UVLO voltage. 2) Upon insertion of a battery, with TEMP higher than TLO and lower than THI and cell voltage higher than the UVLO voltage. RSENSE sets the fast-charge current into the battery. In fast charge, the voltage difference between the BATT- and GND pins is regulated to 250mV. DRV current increases its sink current if this voltage difference falls below 250mV, and decreases its sink current if the volt- age difference exceeds 250mV. fast-charge current (IFAST) = 0.25V/RSENSE Trickle Charge Selecting a fast-charge current (IFAST) of C/2, C, 2C, or 4C ensures a C/16 trickle-charge current. Other fast- charge rates can be used, but the trickle-charge current will not be exactly C/16. The MAX712/MAX713 internally set the trickle-charge current by increasing the current amplifier gain (Figure 6), which adjusts the voltage across RSENSE (see Trickle-Charge VSENSE in the Electrical Characteristics table). BATT- X V+ OPEN REF BATT- 1 0 0 0 0 8 512 256 128 64 CURRENT-SENSE AMPLIFIER PGM3 FAST_CHARGE Av 1.25V V+ DC IN GND DRV GND CC BATT- RSENSE D1 REF VLIMIT CELL_VOLTAGE BATT- BATT- IN_REGULATION C2 Figure 6. Current and Voltage Regulator (linear mode) |
Similar Part No. - MAX712_08 |
|
Similar Description - MAX712_08 |
|
|
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 |