LTC4012-3_15 Datasheet, PDF (9/28 Pages) Linear Technology – High Efficiency, Multi-Chemistry Battery Charger with PowerPath Control

LTC4012-3
Pin Functions
BGATE (Pin 16): External Synchronous NFET Gate Control
Output. This output provides gate drive to an external NMOS
power transistor switch used for synchronous rectification
to increase efficiency in the step-down DC/DC converter.
Operating voltage is GND to INTV_DD. BGATE should be
left floating if not used.
INTV_DD (Pin 17): Internal 5V Regulator Output. This pin
provides a means of bypassing the internal 5V regulator
used to power the LTC4012-3 PWM FET drivers. This sup-
ply shuts down when the LTC4012-3 shuts down. Refer to
the Application Information section for details if additional
power is drawn from this pin by the application circuit.
SW (Pin 18): PWM Switch Node. The LTC4012-3 uses the
voltage on this pin as the source reference for its topside
NFET (PWM switch) driver. Refer to the Applications In-
formation section for additional PCB layout suggestions
related to this critical circuit node. Operating voltage range
is GND to CLN.
TGATE (Pin 19): External NFET Switch Gate Control Output.
This output provides gate drive to an external NMOS power
transistor switch used in the DC/DC converter. Operating
voltage range is GND to (CLN + 5V).
BOOST (Pin 20): TGATE Driver Supply Input. A bootstrap
capacitor is returned to this pin from a charge network
connected to SW and INTV_DD. Refer to the Applications
Information section for complete details on circuit topol-
ogy and component values. Operating voltage ranges from
(INTV_DD – 1V) to (CLN + 5V).
GND (Exposed Pad Pin 21): Ground. The package paddle
provides a single-point ground for the internal voltage
reference and other critical LTC4012-3 circuits. It should be
soldered to a suitable PCB copper ground pad for proper
electrical operation and to obtain the specified package
thermal resistance.
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