Electronic Components Datasheet Search |
|
LTC4070EMS8E Datasheet(PDF) 10 Page - Linear Technology |
|
LTC4070EMS8E Datasheet(HTML) 10 Page - Linear Technology |
10 / 16 page LTC4070 10 4070f APPLICATIONS INFORMATION The LTC4070 can also be used to regulate series-connected battery stacks as illustrated in Figures 3 and 4. Here two LTC4070 devices are used to charge two batteries in series; with or without boosted drive. A single resistor sets the maximum charge/shunt current. The GND pin of the top device is simply connected to the VCC pin of the bottom device. Care must be taken in observing the status output pins of the top device as these signals are not ground ref- erenced. Also, the wall adapter must have a high enough voltage rating to charge both cells. Figure 3. 2-Cell Battery Charger Figure 4. 2-Cell Battery Charger with Boosted Drive NTC Protection The LTC4070 measures battery temperature with a negative temperature coefficient thermistor thermally coupled to the battery. NTC thermistors have temperature characteristics which are specified in resistance-temperature conversion tables. Internal NTC circuitry protects the battery from excessive heat by reducing the float voltage for each 10°C rise in temperature above 40°C (assuming a Vishay curve 2 thermistor). The LTC4070 uses a ratio of resistor values to measure battery temperature. The LTC4070 contains an internal fixed resistor voltage divider from NTCBIAS to GND with four tap points; NTCTH1-NTCTH4. The voltages at these tap points are periodically compared against the voltage at the NTC pin to measure battery temperature. To conserve power, the battery temperature is measured periodically by biasing the NTCBIAS pin to VCC about once every 1.5 seconds. The voltage at the NTC pin depends on the ratio of the NTC thermistor value, RNTC, and a bias resistor, RNOM. Choose RNOM equal to the value of the thermistor at 25°C. RNOM is 10k for a Vishay NTHSO402E3103LT curve 2 thermistor. RNOM must be connected from NTCBIAS to NTC. The ratio of the NTC pin voltage to the NTCBIAS voltage is: RNTC RNTC +RNOM () When the thermistor temperature rises, the resistance drops; and the resistor divider between RNOM and the thermistor lowers the voltage at the NTC pin. An NTC curve 1 thermistor may also be used with the LTC4070. However the temperature trip points are shifted due to the higher negative temperature coefficient of the curve 1 type thermistor. To correct for this difference add a resistor, RFIX, in series with the curve 1 thermistor to shift the ratio, RFIX +RNTC RFIX +RNTC +RNOM () up to the internal resistive divider tap points: NTCTH1 through NTCTH4.Fora100kcurve1thermistorat70°C(with RNOM = 100k) choose RFIX = 3.92kΩ. The temperature trip LTC4070 ADJ RIN GND WALL ADAPTER FLOAT IF NOT NEEDED FLOAT FLOAT IF NOT NEEDED FLOAT Li-Ion BATTERY NTCBIAS NTC VCC VCC1 + 4070 F03 LTC4070 ADJ GND Li-Ion BATTERY NTCBIAS NTC VCC VCC2 + LTC4070 ADJ RIN GND WALL ADAPTER FLOAT IF NOT NEEDED FLOAT FLOAT IF NOT NEEDED FLOAT Li-Ion BATTERY NTCBIAS DRV Q1 NTC VCC VCC1 VCC2 + 4070 F04 LTC4070 ADJ GND Li-Ion BATTERY NTCBIAS Q1, Q2: Si3469DV DRV Q2 NTC VCC + |
Similar Part No. - LTC4070EMS8E |
|
Similar Description - LTC4070EMS8E |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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 |