Datasheet LT1571 (Analog Devices) - 4

LT1571 Series
ELECTRICAL CHARACTERISTICS The
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denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25
°
C. VCC = 16V (LT1571-1, LT1571-2), VCC = 10V (LT1571-5), VBAT = 8V (LT1571-1,LT1571-2), VBAT = 4V (LT1571-5), no load on any outputs unless otherwise noted. (Note 6) PARAMETER CONDITIONS MIN TYP MAX UNITS Switch
Switch ON Resistance ISW = 1.5A, VBOOST – VSW ≥ 2V ● 0.3 0.5 Ω ISW = 1A, VBOOST – VSW < 2V (Unboosted) ● 2.0 Ω ∆IBOOST/∆ISW During Switch ON VBOOST = (VCC + 8V), ISW ≤ 1A 20 35 mA/A Switch OFF Leakage Current VSW = 0V, VCC ≤ 20V 2 100 µA VSW = 0V, 20V < VCC ≤ 26V 4 200 µA Maximum VBAT with Switch ON ● VCC – 2 V Minimum IPROG for Switch ON 1 4 27 µA Minimum IPROG for Switch OFF ● 1 2.4 mA
Current Sense Amplifier Inputs (SENSE, BAT)
Sense Resistance (RS1) 0.08 0.12 Ω Total Resistance from SENSE to BAT (Note 3) 0.2 0.25 Ω BAT Bias Current (Note 4) VC < 0.3V – 200 – 375 µA VC > 0.6V ● 700 1300 µA VC < 40mV 5 µA
Oscillator
Switching Frequency LT1571-1, LT1571-2 180 200 220 kHz LT1571-5 440 500 550 kHz Switching Frequency Tolerance All Conditions of VCC, Temperature, LT1571-1, LT1571-2 ● 170 200 230 kHz LT1571-1, LT1571-2, TJ < 0°C 160 230 kHz LT1571-5 ● 425 500 575 kHz LT1571-5, TJ < 0°C 400 575 kHz Maximum Duty Cycle LT1571-1, LT1571-2 ● 87 % LT1571-1, LT1571-2, TA = 25°C (Note 7) 90 93 % LT1571-5 ● 77 81 %
Current Amplifier (CA2)
Transconductance VC = 1V, IVC = ±1µA 125 210 550 µmho Maximum VC for Switch OFF ● 0.6 V IVC Current (Out of Pin) VC ≥ 0.6V 100 µA 0.2V < VC < 0.45V 3 mA VC < 40mV (Shutdown) 300 µA
Note 1:
Absolute Maximum Ratings are those values beyond which the life
Note 5:
A linear interpolation can be used for reference voltage of a device may be impaired. specification between 0°C and – 40°C.
Note 2:
The LT1571 is guaranteed to meet performance specifications
Note 6:
Maximum allowable ambient temperature may be limited by power from 0°C to 70°C. Specifications over the – 40°C to 85°C operating dissipation. Parts may not necessarily be operated simultaneously at temperature range are assured by design, characterization and correlation maximum power dissipation and maximum ambient temperature. with statistical process controls. Temperature rise calculations must be done as shown in the Applications
Note 3:
Sense resistor RS1 and package bond wires. Information section to ensure that maximum junction temperature does
Note 4:
Current (≈ 700µA) flows into the pins during normal operation and not exceed the 125°C limit. With high power dissipation, maximum also when an external shutdown signal on the V ambient temperature may be less than 70°C. C pin is greater than 0.3V. Current decreases to ≈ 200µA and flows out of the pins when external
Note 7:
91% maximum duty cycle is guaranteed by design if VBAT or VX shutdown holds the VC pin below 0.3V but above shutdown threshold. (see Figure 8 in Application Information) is kept between 3V and 5V. Current drops to near zero when input voltage collapses. See External
Note 8:
See “Lithium-Ion Charging Completion” in the Applications Shutdown in Applications Information section. Information section. 4