Datasheet LTC1871 (Analog Devices) - 4

LTC1871
ELECTRICAL CHARACTERISTICS The
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denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VIN = VINTVCC = 5V, VRUN = 1.5V, RFREQ = 80k, VMODE/SYNC = 0V, unless otherwise specifi ed. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
DMAX Maximum Duty Cycle 87 92 97 % I-Grade or H-Grade (Note 2) ● 87 92 97 % fSYNC/fOSC Recommended Maximum Synchronized fOSC = 300kHz (Note 6) 1.25 1.30 Frequency Ratio fOSC = 300kHz (Note 6), I-Grade or H-Grade (Note 2) ● 1.25 1.30 tSYNC(MIN) MODE/SYNC Minimum Input Pulse Width VSYNC = 0V to 5V 25 ns tSYNC(MAX) MODE/SYNC Maximum Input Pulse Width VSYNC = 0V to 5V 0.8/fOSC ns VIL(MODE) Low Level MODE/SYNC Input Voltage 0.3 V I-Grade or H-Grade (Note 2) ● 0.3 V VIH(MODE) High Level MODE/SYNC Input Voltage 1.2 V I-Grade or H-Grade (Note 2) ● 1.2 V RMODE/SYNC MODE/SYNC Input Pull-Down Resistance 50 kΩ VFREQ Nominal FREQ Pin Voltage 0.62 V
Low Dropout Regulator
VINTVCC INTVCC Regulator Output Voltage VIN = 7.5V 5.0 5.2 5.4 V VIN = 7.5V, I-Grade (Note 2) ● 5.0 5.2 5.4 V VIN = 7.5V, H-Grade (Note 2) ● 4.95 5.2 5.45 V ΔVINTVCC INTVCC Regulator Line Regulation 7.5V ≤ VIN ≤ 15V 8 25 mV ΔVIN1 ΔVINTVCC INTVCC Regulator Line Regulation 15V ≤ VIN ≤ 30V 70 200 mV ΔVIN2 VLDO(LOAD) INTVCC Load Regulation 0 ≤ IINTVCC ≤ 20mA, VIN = 7.5V – 2 –0.2 % VDROPOUT INTVCC Regulator Dropout Voltage VIN = 5V, INTVCC Load = 20mA 280 mV IINTVCC Bootstrap Mode INTVCC Supply RUN = 0V, SENSE = 5V 10 20 μA Current in Shutdown I-Grade (Note 2) ● 30 μA H-Grade (Note 2) ● 50 μA
GATE Driver
tr GATE Driver Output Rise Time CL = 3300pF (Note 7) 17 100 ns tf GATE Driver Output Fall Time CL = 3300pF (Note 7) 8 100 ns
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 4:
The dynamic input supply current is higher due to power MOSFET may cause permanent damage to the device. Exposure to any Absolute gate charging (QG • fOSC). See Applications Information. Maximum Rating condition for extended periods may affect device
Note 5:
The LTC1871 is tested in a feedback loop which servos VFB to reliability and lifetime. the reference voltage with the ITH pin forced to the midpoint of its voltage
Note 2:
The LTC1871E is guaranteed to meet performance specifi cations range (0.3V ≤ VITH ≤ 1.2V, midpoint = 0.75V). from 0°C to 85°C operating temperature. Specifi cations over the – 40°C to
Note 6:
In a synchronized application, the internal slope compensation 85°C operating temperature range are assured by design, characterization gain is increased by 25%. Synchronizing to a signifi cantly higher ratio will and correlation with statistical process controls. The LTC1871I is reduce the effective amount of slope compensation, which could result in guaranteed over the full –40°C to 125°C operating temperature range subharmonic oscillation for duty cycles greater than 50%. and the LTC1871H is guaranteed over the full –40°C to 150°C operating
Note 7:
Rise and fall times are measured at 10% and 90% levels. temperature range.
Note 3:
TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: TJ = TA + (PD • 110°C/W) 1871fe 4