DS2715 Dallas Semiconducotr, DS2715 Datasheet
DS2715
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DS2715 Summary of contents
Page 1
... A user selectable charge timer allows charge rates from 0.15C to 2C. Fast-charge, top-off and charge done modes are included for highly reliable, safe charging of NiMH cells. Discharge mode allows the DS2715 to enter a low power sleep state while the cell pack is being discharged. FEATURES § ...
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ABSOLUTE MAXIMUM RATINGS* Voltage on V and V Pins with Respect Voltage on LED1 and LED2 Pins Voltage on SNS- Voltage on C BIAS Voltage on all Other Pins Continuous Sink Current V CH Operating Temperature ...
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AC ELECTRICAL CHARACTERISTICS PARAMETER SYMBOL UVLO Debounce Time Current Sense Comparator Propagation Delay Discharge Detect Propagation Delay Return To Normal Function (Op-Amp or Comparator Mode) R Timing Accuracy T Internal Clock Accuracy ELECTRICAL CHARACTERISTICS: CHARGING PARAMETER SYMBOL Fast Charge Comparator ...
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Note 1: Voltages relative Note 2: Does not include current through V Note 3: Below this voltage no I/O pins are active. Note 4: Does not include tolerance of R Note 5: V and resistor tolerances must ...
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... Figure 1. BLOCK DIAGRAM Cbias VDD HV V UVLO Disable during Div discharge Oscillator LED1 HV LED2 HV Pwr Rt start-up test Rt Charge Rt Timer DS2715 Pwr R Regulator E F Ref UVLO State Machine Pre-Charge Low Cells Fast Charge Exit on Full Or Timeout Mode 25% Top-Off Charge Ref (Set by Timer) Vsns Ref ...
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... Discharge Vbatt < 1V Mode Pwr=Low LEDs = OFF Vch = LOW Discharge Latch Still Set? t < Fast Timeout Discharge latch set t < Topoff Timeout Discharge latch set DS2715 State Diagram -V UVLO-HYS Reset V > UVLO Standby power Check Rt, set mode Vch = Hi-Z LEDx = Hi-Z Vbatt>1.65 PreCHG Vref = 0 ...
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... DD Presence The DS2715 enters the PRESENCE state whenever V source is present, but no cell is available to charge. The DS2715 will remain in the presence state until a cell is inserted into the circuit causing the voltage on V valid charging range between 0°C and 45°C (T will enter pre-charge. If cells are inserted, but the temperature is outside the valid charging range the DS2715 will remain in the PRESENCE state until the cell temperature falls within the valid charging range ...
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... LED is driven on to indicate charge completion. A maintenance charge can be applied to the cells by providing a resistive path from the cell pack to the charge source bypassing the regulator. See the example circuit in Figure 3. The DS2715 remains in DONE until a cell voltage greater than 1.65V (V detected on V indicating the cell pack has been removed ...
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... Figure 3. TYPICAL APPLICATION CIRCUIT FOR A 3-CELL STACK LOAD CR1 LED2 LED1 +9VDC R12 R10 0.075 CR2 100 470 IRF9Z24 DS2715 LED1 Vch LED2 Vbatt Vdd Div Rt R6 68K Mode SNS+ Cbias VSS THM VSS CTG SNS- C4 0.1 uF R11 ...
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... TO Current-Sense Comparator Mode The comparator in the DS2715 switches between ON and OFF and is capable of driving a PNP bipolar or a PMOS transistor, enabling the use of a switched-mode power stage. Hysteresis on the comparator input provides noise rejection closed-loop regulation circuit, the comparator regulates voltage across the sense resistor ...
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... Accurate temperature sensing is needed to determine end of charge by dT/dt and to detect over temperature fault conditions. Connecting an external 10kW NTC thermistor between THM and V Div and THM allows the DS2715 to sense temperature. To sense the temperature of the cell pack, locate the thermistor close to the body of a cell, preferably in the middle of the cell pack. Several recommended 10kW thermistors are shown in Table 2 ...
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LED1 and LED2 Outputs Open-drain outputs LED1 and LED2 pull low to indicate charge status. When inactive, the outputs are high impedance. LED1 displays the state of charge and LED2 displays the charge results. The LED1 pin drives low in ...