Datasheet LTC4011 (Analog Devices) - 9

LTC4011 pin FuncTions
VCDIV (Pin 9):
Average Cell Voltage Resistor Divider Termi-
PGND (Pin 16):
Power Ground. This pin provides a return nation. The LTC4011 connects this pin to GND provided the for switching currents generated by internal LTC4011 cir- charger is not in shutdown. VCDIV is an open-drain output cuits. Externally, PGND and GND should be wired together to GND with an operating voltage range of GND to BAT. using a very low impedance connection. Refer to PCB
TIMER (Pin 10):
Charge Timer Input. A resistor connected Layout Considerations in the Applications Information between TIMER and GND programs charge cycle timing section for additional grounding details. limits. Refer to the Applications Information section for
TGATE (Pin 17):
External P-channel MOSFET Gate Control complete details. Operating voltage range is GND to 1V. Output. This output provides gate drive to an external PMOS
SENSE (Pin 11):
Charge Current Sense Input. An external power transistor switch used in the DC/DC converter. Op- resistor between this input and BAT is used to program erating voltage range varies as a function of VCC. Refer to charge current. Refer to the Applications Information the Electrical Characteristics table for specific voltages. section for complete details on programming charge
VCC (Pin 18):
Power Input. External PowerPath control current. Operating voltage ranges from (BAT – 50mV) to circuits normally connect either the DC input power sup- (BAT + 200mV). ply or the battery to this pin. Refer to the Applications
BAT (Pin 12):
Battery Pack Connection. The LTC4011 uses Information section for further details. Suggested applied the voltage on this pin to control current sourced from voltage range is GND to 34V. VCC to the battery during charging. Allowable operating
READY (Pin 19):
Active-Low Ready-to-Charge Output. voltage range is GND to VCC. The LTC4011 connects this pin to GND if proper operating
TOC (Pin 13):
Active-Low Top-Off Charge Indicator Out- voltages for charging are present. Refer to the Operation put. The LTC4011 indicates the top-off charge state for section for complete details on charge qualification. This NiMH batteries by connecting this pin to GND. Refer to output is capable of driving an LED and should be left the Operation and Applications Information sections for floating if not used. READY is an open-drain output to further details. This output is capable of driving an LED GND with an operating voltage range of GND to VCC. and should be left floating if not used. TOC is an open-
INFET (Pin 20):
PowerPath Control Output. For very low drain output to GND with an operating voltage range of dropout applications, this output may be used to drive GND to VCC. the gate of an input PMOS pass transistor connected
INTV
between the DC input (DCIN) and the raw system supply
DD (Pin 14):
Internal 5V Regulator Output. This pin provides a means of bypassing the internal 5V regulator rail (VCC). INFET is internally clamped about 6V below VCC. used to power the BGATE output driver. Typically, power Maximum operating voltage is VCC. INFET should be left should not be drawn from this pin by the application floating if not used. circuit. Refer to the Application Information section for
Exposed Pad (Pin 21):
This pin provides enhanced additional details. thermal properties for the TSSOP. It must be soldered
BGATE (Pin 15):
External Synchronous N-channel MOSFET to the PCB copper ground to obtain optimum thermal Gate Control Output. This output provides gate drive to performance. an optional external NMOS power transistor switch used for synchronous rectification to increase efficiency in the step-down DC/DC converter. Operating voltage is GND to INTVDD. BGATE should be left floating if not used. 4011fb Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Related Parts