Datasheet LTC3850-2 (Analog Devices) - 4

LTC3850-2
ELECTRICAL CHARACTERISTICS The
l
denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C, VIN = 15V, VRUN1,2 = 5V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Oscillator and Phase-Locked Loop
fNOM Nominal Frequency VFREQ = 1.2V 450 500 550 kHz fLOW Lowest Frequency VFREQ = 0V 210 250 290 kHz fHIGH Highest Frequency VFREQ ≥ 2.4V 700 780 860 kHz RMODE/PLLIN MODE/PLLIN Input Resistance 250 kΩ IFREQ Phase Detector Output Current Sinking Capability fMODE < fOSC –13 μA Sourcing Capability fMODE > fOSC 13 μA
PGOOD Output
VPGL PGOOD Voltage Low IPGOOD = 2mA 0.1 0.3 V IPGOOD PGOOD Leakage Current VPGOOD = 5V ±2 μA VPG PGOOD Trip Level VFB with Respect to Set Regulated Voltage VFB Ramping Negative –5 – 7.5 –10 % VFB Ramping Positive 5 7.5 10 %
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 4:
The LTC3850I-2 is tested in a feedback loop that servos VITH1,2 to may cause permanent damage to the device. Exposure to any Absolute a specifi ed voltage and measures the resultant VFB1,2. Maximum Rating condition for extended periods may affect device
Note 5:
Dynamic supply current is higher due to the gate charge being reliability and lifetime. delivered at the switching frequency. See Applications Information.
Note 2:
The LTC3850I-2 is guaranteed to meet performance specifi cations
Note 6:
Rise and fall times are measured using 10% and 90% levels. Delay over the –40°C to 85°C operating temperature range. times are measured using 50% levels.
Note 3:
T
Note 7:
The minimum on-time condition is specifi ed for an inductor J is calculated from the ambient temperature TA and power dissipation P peak-to-peak ripple current ≥40% of I D according to the following formulas: MAX (see Minimum On-Time Considerations in the Applications Information section). LTC3850IGN-2: TJ = TA + (PD • 95°C/W)
TYPICAL PERFORMANCE CHARACTERISTICS Effi ciency vs Output Current Effi ciency vs Output Current Effi ciency and Power Loss and Mode and Mode vs Input Voltage
100 100 100 2000 VIN = 12V VOUT = 3.3V 90 VOUT = 1.8V 90 BURST IOUT = 2A BURST 80 80 95 1500 POWER LOSS (mW) 70 70 EFFICIENCY 60 DCM DCM 60 50 50 90 1000 40 40 EFFICIENCY (%) POWER LOSS EFFICIENCY (%) EFFICIENCY (%) 30 30 CCM CCM 85 500 20 20 10 10 VIN = 12V VOUT = 3.3V 0 0 80 0 10 100 1000 10000 10 100 1000 10000 5 10 15 20 25 LOAD CURRENT (mA) LOAD CURRENT (mA) INPUT VOLTAGE (V) 38502 G01 38502 G02 38502 G03 CIRCUIT OF FIGURE 14 CIRCUIT OF FIGURE 14 CIRCUIT OF FIGURE 14 38502f 4