Datasheet LTC4012, LTC4012-1, LTC4012-2 (Analog Devices) - 9

LTC4012/ LTC4012-1/LTC4012-2 pin Functions
PROG (Pin 13):
Charge Current Programming and Monitor-
SW (Pin 18):
PWM Switch Node. The LTC4012 uses the ing Pin. An external resistance connected between PROG voltage on this pin as the source reference for its topside and GND, along with the current sense and PWM input NFET (PWM switch) driver. Refer to the Applications In- resistors, programs the maximum charge current. The formation section for additional PCB layout suggestions voltage on this pin can also provide a linearized indicator related to this critical circuit node. Operating voltage range of charge current. Refer to the Applications Information is GND to CLN. section for complete details on current programming and
TGATE (Pin 19):
External NFET Switch Gate Control Output. monitoring. Operating voltage range is GND to INTVDD. This output provides gate drive to an external NMOS power
CSN (Pin 14):
Charge Current Sense Negative In- transistor switch used in the DC/DC converter. Operating put. Place an external input resistor (RIN, Figure 1) voltage range is GND to (CLN + 5V). between this pin and the negative side of the charge
BOOST (Pin 20):
TGATE Driver Supply Input. A bootstrap current sense resistor. Operating voltage ranges from capacitor is returned to this pin from a charge network (BAT – 50mV) to (BAT + 200mV). connected to SW and INTVDD. Refer to the Applications
CSP (Pin 15):
Charge Current Sense Positive Input. Information section for complete details on circuit topol- Place an external input resistor (RIN, Figure 1) be- ogy and component values. Operating voltage ranges from tween this pin and the positive side of the charge (INTVDD – 1V) to (CLN + 5V). current sense resistor. Operating voltage ranges from
GND (Exposed Pad Pin 21):
Ground. The package paddle (BAT – 50mV) to (BAT + 200mV). provides a single-point ground for the internal voltage
BGATE (Pin 16):
External Synchronous NFET Gate Control reference and other critical LTC4012 circuits. It must be Output. This output provides gate drive to an external NMOS soldered to a suitable PCB copper ground pad for proper power transistor switch used for synchronous rectification electrical operation and to obtain the specified package to increase efficiency in the step-down DC/DC converter. thermal resistance. Operating voltage is GND to INTVDD. BGATE should be left floating if not used.
INTVDD (Pin 17):
Internal 5V Regulator Output. This pin provides a means of bypassing the internal 5V regulator used to power the LTC4012 PWM FET drivers. This supply shuts down when the LTC4012 shuts down. Refer to the Application Information section for details if additional power is drawn from this pin by the application circuit. 4012fa Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Test Circuits Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts