Datasheet LT8610 (Analog Devices) - 8

LT8610
TYPICAL PERFORMANCE CHARACTERISTICS Transient Response Start-Up Dropout Performance Start-Up Dropout Performance
ILOAD 1A/DIV VIN VIN VIN VIN 2V/DIV 2V/DIV VOUT V V 200mV/DIV V OUT OUT OUT VOUT 2V/DIV 2V/DIV 50µs/DIV 8610 G36 100ms/DIV 8610 G37 100ms/DIV 8610 G38 50mA TO 1A TRANSIENT 2.5Ω LOAD 20Ω LOAD 12V (2A IN REGULATION) (250mA IN REGULATION) IN, 5VOUT COUT = 47µF
PIN FUNCTIONS SYNC (Pin 1):
External Clock Synchronization Input.
VIN (Pins 5, 6):
The VIN pins supply current to the LT8610 Ground this pin for low ripple Burst Mode operation at low internal circuitry and to the internal topside power switch. output loads. Tie to a clock source for synchronization to These pins must be tied together and be locally bypassed. an external frequency. Apply a DC voltage of 3V or higher Be sure to place the positive terminal of the input capaci- or tie to INTVCC for pulse-skipping mode. When in pulse- tor as close as possible to the VIN pins, and the negative skipping mode, the IQ will increase to several hundred µA. capacitor terminal as close as possible to the PGND pins. Do not float this pin.
PGND (Pins 7, 8):
Power Switch Ground. These pins are
TR/SS (Pin 2):
Output Tracking and Soft-Start Pin. This the return path of the internal bottom-side power switch pin allows user control of output voltage ramp rate during and must be tied together. Place the negative terminal of start-up. A TR/SS voltage below 0.97V forces the LT8610 the input capacitor as close to the PGND pins as possible. to regulate the FB pin to equal the TR/SS pin voltage. When
SW (Pins 9, 10, 11):
The SW pins are the outputs of the TR/SS is above 0.97V, the tracking function is disabled internal power switches. Tie these pins together and con- and the internal reference resumes control of the error nect them to the inductor and boost capacitor. This node amplifier. An internal 2.2μA pull-up current from INTVCC should be kept small on the PCB for good performance. on this pin allows a capacitor to program output voltage slew rate. This pin is pulled to ground with an internal 230Ω
BST (Pin 12):
This pin is used to provide a drive voltage, MOSFET during shutdown and fault conditions; use a series higher than the input voltage, to the topside power switch. resistor if driving from a low impedance output. This pin Place a 0.1µF boost capacitor as close as possible to the IC. may be left floating if the tracking function is not needed.
INTVCC (Pin 13):
Internal 3.4V Regulator Bypass Pin.
RT (Pin 3):
A resistor is tied between RT and ground to The internal power drivers and control circuits are pow- set the switching frequency. ered from this voltage. INTVCC maximum output cur- rent is 20mA. Do not load the INTV
EN/UV (Pin 4):
The LT8610 is shut down when this pin CC pin with external circuitry. INTV is low and active when this pin is high. The hysteretic CC current will be supplied from BIAS if V threshold voltage is 1.00V going up and 0.96V going BIAS > 3.1V, otherwise current will be drawn from VIN. Voltage on INTV down. Tie to V CC will vary between 2.8V and 3.4V when IN if the shutdown feature is not used. An V external resistor divider from V BIAS is between 3.0V and 3.6V. Decouple this pin to power IN can be used to program ground with at least a 1μF low ESR ceramic capacitor a VIN threshold below which the LT8610 will shut down. placed close to the IC. 8610fa 8 For more information www.linear.com/LT8610 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 Typical Applications Package Description Typical Application Related Parts