Datasheet LTC4071 (Analog Devices) - 7

LTC4071
BLOCK DIAGRAM
VIN V R LTC4071 CC IN SYSTEM ADJ 3-STATE LOAD PULSED DETECT DUTY CYCLE = 0.003% 30µs – 200µs + BODY CLK DIODE 0.9sec – 7sec OSC – NTCBIAS BAT MP1 RNOM 10k NTC ADC + T 10k LBSEL LBSEL MUST BE TIED TO VCC OR GND Li-Ion BATTERY HBO + + – 1.2V 1.2V –EA MP2 GND 4071 BD
Figure 1. Block Diagram OPERATION
The LTC4071 provides a simple, reliable, and high perfor- enough for VCC to reach VLBC_VCC to ensure that MP1 mance battery protection and charging solution by pre- turns on. The user may detect the connected state by venting the battery voltage from exceeding a programmed observing periodic pulses at the NTCBIAS pin that only level. Its shunt architecture requires just one resistor from occur once VCC has risen above VLBC_VCC, and cease once the input supply to charge and protect the battery in a VCC falls below VLBD. Depending on the capacity of the wide range of battery applications. When the input supply battery and the input decoupling capacitor, the VCC voltage is removed and the battery voltage is below the high bat- generally falls to VBAT when MP1 turns on; rather than tery output threshold, the LTC4071 consumes just 550nA VBAT rising to VCC. The internal PFET then reconnects the from the battery. If the battery voltage falls below the battery to VCC and the charge rate is determined by the programmable low battery disconnect level, the battery input voltage, the battery voltage, and the input resistor: disconnects from VCC, protecting the battery from over- discharge either by the load connected to V (VIN – VBAT ) CC or from the ICHG = LTC4071 quiescent current. RIN When an input supply is present the battery charges As the battery voltage approaches the float voltage, the through the body diode of the internal disconnect PFET, LTC4071 shunts current away from the battery thereby MP1, until the battery voltage rises above the low- reducing the charge current. The LTC4071 can shunt battery connect threshold. Select an input voltage large up to 50mA. The shunt current limits the maximum charge current. Rev. D For more information www.analog.com 7 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts