Datasheet LT3462, LT3462A (Analog Devices) - 4

LT3462/LT3462A
TYPICAL PERFORMANCE CHARACTERISTICS Oscillator Frequency (LT3462) Current Limit SDREF Minus FB Pin Voltage
1.6 480 1.29 TA = 25°C 1.5 1.28 LT3462 360 1.4 LT3462A 1.27 1.3 240 1.26 1.2 1.25 FREQUENCY (MHz) CURRENT LIMIT (mA) SDREF MINUS FB (V) 120 1.1 1.24 1.0 0 1.23 –40 –20 0 20 40 60 80 100 10 20 30 40 50 60 70 80 90 –40 –20 0 20 40 60 80 100 TEMPERATURE (°C) DUTY CYCLE (%) TEMPERATURE (°C) 3462 G01 3462 G02 3462 G03
Quiescent Current in Oscillator Frequency (LT3462A) FB Bias Current Shutdown Mode
3.2 0 10 TA = 25°C TA = 25°C –5 FB = N/C 3.0 –10 8 –15 2.8 –20 6 2.6 –25 –30 4 FREQUENCY (MHz) 2.4 FB BIAS CURRENT (nA) –35 QUIESCENT CURRENT (A) –40 2 2.2 –45 2.0 –50 0 –40 –20 0 20 40 60 80 100 –40 –20 0 20 40 60 80 100 0 4 8 12 16 TEMPERATURE (°C) TEMPERATURE (°C) SUPPLY VOLTAGE (V) 3462 G04 3462 G05 3462 G06
PIN FUNCTIONS (TSOT-23/DFN) SW (Pin 1/Pin 4):
Switch Pin. Connect to external induc‑ regulator. At turn‑on, a 180µA internal source pulls the tor L1 and positive terminal of transfer cap. pin to the regulation voltage. The SDREF pin can supply
GND (Pin 2/Pins 2, 3):
Ground. Tie directly to local up to 80µA at 1.265V to bias the feedback resistor divider. ground plane. An optional soft‑start circuit capacitor connects from this pin to –VOUT.
FB (Pin 3/Pin 1):
Feedback Pin. Connect resistive divider tap here. Set R1 according to R1 = R2 • (V
D (Pin 5/Pin 7):
Anode Terminal of Integrated Schottky OUT/1.265V). In shutdown, a proprietary shutdown bias current cancel‑ Diode. Connect to negative terminal of transfer cap and lation circuit allows the internal 3µA source to pull up the external inductor L2. SDREF pin, even with residual negative voltage on VOUT.
VIN (Pin 6/Pin 5):
Input Supply Pin. Must be locally
SDREF (Pin 4/Pin 8):
Dual Function Shutdown and bypassed. 1.265V Reference Output Pin. Pull to GND with exter‑
Exposed Pad (NA/Pin 9):
GND. The exposed pad should nal N‑FET to turn regulator off. Turn‑off pull‑down and be soldered to the PCB ground to achieve the rated ther‑ a 2µA internal source will pull SDREF up to turn‑on the mal performance. Rev A 4 For more information www.analog.com Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts