Datasheet LTC3105 (Analog Devices) - 6

LTC3105
PIN FUNCTIONS (DFN/MSOP) FB (Pin 1/Pin 1):
Step-Up Converter Feedback Input.
GND (Exposed Pad Pin 11/Pins 6, 7) :
Small Signal and Connect the VOUT resistor divider tap to this input. The Power Ground for the IC. The GND connections should be output voltage can be adjusted between 1.6V and 5.25V. soldered to the PCB ground using the lowest impedance
LDO (Pin 2/Pin 2):
LDO Regulator Output. Connect a 4.7µF path possible. or larger capacitor between LDO and GND.
SW (Pin 7/Pin 9):
Switch Pin. Connect an inductor between
FBLDO (Pin 3/Pin 3):
LDO Feedback Input. Connect the SW and VIN. PCB trace lengths should be as short as pos- LDO resistive divider tab to this input. Alternatively, con- sible to reduce EMI. While the converter is sleeping or is necting FBLDO directly to GND will configure the LDO in shutdown, the internal antiringing switch connects the output voltage to be internally set at 2.2V (nominal). SW pin to the VIN pin in order to minimize EMI.
SHDN (Pin 4/Pin 4):
Logic Controlled Shutdown Input.
PGOOD (Pin 8/Pin 10):
Power Good Indicator. This is an With SHDN open, the converter is enabled by an internal open-drain output. The pull-down is disabled when VOUT 2MΩ pull-up resistor. The SHDN pin should be driven with has achieved the voltage defined by the feedback divider an open-drain or open-col ector pul -down and floated until on the FB pin. The pull-down is also disabled while the IC the converter has entered normal operation. Excessive is in shutdown or start-up mode. loading on this pin may cause a failure to complete start-up.
VOUT (Pin 9/Pin 11):
Step-Up Converter Output. This is the SHDN = Low: IC Disabled drain connection of the main output internal synchronous rectifier. A 10µF or larger capacitor must be connected SHDN = High: IC Enabled between this pin and GND. The PCB trace length from the
MPPC (Pin 5/Pin 5):
Set Point Input for Maximum VOUT pin to the output filter capacitor should be as short Power Point Control. Connect a resistor from MPPC to and wide as possible. GND to program the activation point for the MPPC loop.
AUX (Pin 10/Pin 12):
Auxiliary Voltage. Connect a 1µF To disable the MPPC circuit, connect MPPC directly capacitor between this pin and GND. This pin is used by to GND. the start-up circuitry to generate a voltage rail to power
V
internal circuitry until the main output reaches regulation.
IN (Pin 6/Pin 8):
Input Supply. Connect a decoupling capacitor between this pin and GND. The PCB trace length AUX and VOUT are internally connected together once VOUT from the V exceeds V IN pin to the decoupling capacitor should be as AUX. short and wide as possible. When used with high imped- ance sources such as photovoltaic cells, this pin should have a 10µF or larger decoupling capacitor. 3105fb 6 For more information www.linear.com/LTC3105 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Application Related Parts