Datasheet LTC3421 (Analog Devices) - 6

LTC3421
TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C, unless otherwise noted. Burst Mode Threshold vs RBURST FB Voltage Frequency Accuracy
180 1.24 1.03 160 140 1.23 1.01 120 100 1.22 0.99 80 VOLTAGE (V) 60 FREQUENCY (MHz) OUTPUT CURRENT (mA) OUT OF BURST 1.21 0.97 40 20 INTO BURST 0 1.20 0.95 20 70 120 –45 –30 –15 0 15 30 45 60 75 90 –45 –30 –15 0 15 30 45 60 75 90 RBURST (kΩ) TEMPERATURE (°C) TEMPERATURE (°C) 3421 G10 3421 G11 3421 G12
Burst Mode Quiescent Current Current Limit Accuracy RDS(ON)
20 1.70 0.20 RLIM = 105k 1.65 0.18 1.60 0.16 15 PMOS 1.55 0.14 1.50 0.12 NMOS 10 1.45 0.10 1.40 0.08 CURRENT (µA) CURRENT (A) RESISTANCE (Ω) 1.35 0.06 5 1.30 0.04 1.25 0.02 0 1.20 0 –45 –30 –15 0 15 30 45 60 75 90 –45 –30 –15 0 15 30 45 60 75 90 –45 –30 –15 0 15 30 45 60 75 90 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) 3421 G14 3421 G15 3421 G13
PIN FUNCTIONS FB (Pin 1):
Feedback Pin. Connect resistor divider tap
ENB (Pin 4):
Reference Output (VREF) Enable. When the here. The output voltage can be adjusted from 2.4V to converter is enabled (SHDN = High), forcing ENB = High 5.25V. The feedback reference voltage is typically 1.220V. enables the VREF output, while forcing ENB = Low disables
SHDN (Pin 2):
Shutdown Pin. Less than 0.25V on this the VREF output and lowers the quiescent current by 5µA. pin shuts down the IC. The IC is enabled when the SHDN The low-battery comparator is always active when the voltage is greater than 1V. Once V converter is enabled. In shutdown, both the VREF out- OUT is above 2.2V, hysteresis is applied to the pin (–500nA out of the pin) put and low-battery comparator are disabled unless both allowing it to operate at a logic high while the battery can VOUT ≥ 2.5V and ENB = High. Under these conditions, both drop to 0.5V. the VREF output and low-battery comparator are enabled.
VREF (Pin 3):
Buffered 1.22V Reference Output. This pin can source up to 100µA and sink up to 8µA. This pin must be decoupled with a 0.1µF capacitor for stability. Rev. A 6 For more information www.analog.com Document Outline Description Typical Application Absolute Maximum Ratings Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Package Description Typical Application Related Parts Features Applications Typical Application Description Absolute Maximum Ratings Order Information Electrical Characteristics Package/Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Low Voltage Start-Up Low Noise Fixed Frequency Operation Burst Mode Operation Output Disconnect and Inrush Limiting Applications Information Component Selection Typical Application Package Description Revision History Typical Application Related Parts