LTC4311IDC-TRPBF

LTC4311 Low Voltage I2C/SMBus Accelerator FEATURES ■ ■ DESCRIPTION The LTC®4311 is a dual I2C active pull-up designed to enhance data transmission speed and reliability for bus loading conditions well beyond the 400pF I2C specification limit. The LTC4311 operates at supply voltages from 1.6V to 5.5V and is also compatible with SMBus. The LTC4311 allows multiple device connections or a longer, more capacitive interconnect, without compromising slew rates or bus performance, by using two slew limited pull-up currents. During positive bus transitions, the LTC4311 provides slew limited pull-up currents to quickly slew the I2C or SMBus lines to the bus pull-up voltage. During negative transitions or steady DC levels, the currents are disabled to improve negative slew rate, and improve low state noise margins. An auto detect standby mode reduces supply current if both SCL and SDA are high. When disabled, the LTC4311 goes into low ( VTHR, VCC = 1.8V, 5.5V Bus Capacitance = 400pF VCC = 3V (Note 4) , (Note 5) The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VCC = 3.3V, unless otherwise noted. CONDITIONS ● ● ● ● ● ● ● ● ● ● ● ● ● ● MIN 1.6 TYP 200 26 MAX 5.5 300 45 ±5 UNITS V μA μA μA mA ICC_STANDBY Supply Current, Standby Mode ICC_DISABLED Supply Current, Disabled IPULLUPAC IBUS(IN) IENABLE(IN) VTHR Transient Boosted Pull-up Current BUS1,BUS2, Input Leakage Current ENABLE Input Leakage Current Bus Input Threshold Voltage 2.5 5 ±5 ±10 μA μA V V V V V/μs ns kHz 0.45 0.65 0.68 0.4 0.55 0.75 0.78 1 0.2 0.65 0.85 0.88 1.5 0.5 300 400 Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: All currents into pins are positive. All voltages are referenced to GND unless otherwise specified. Note 3: Thermal characteristics are determined with exposed pad soldered to GND plane. If the exposed pad is left open, thermal characteristics can be drastically different. Note 4: The rise time of an I2C bus line is calculated from VIL(MAX) to VIH(MIN) or 0.9V to 2.1V (with VCC = 3V). This parameter is guaranteed by design and not tested. With a minimum boosted pull-up current of 2.5mA: Rise Time = (2.1V – 0.9V) • 400pF/2.5mA = 0.19μs. Note 5: Determined by design, not tested in production. 4311fa 3 LTC4311 TYPICAL PERFORMANCE CHARACTERISTICS Boost Pull-Up Current vs Temperature 40 BOOST PULL-UP CURRENT (mA) BOOST PULL-UP CURRENT (mA) 35 30 25 20 15 10 5 VCC = 3.3V VCC = 2.5V VCC = 1.8V 0 60 40 20 TEMPERATURE (°C) 80 100 4311 G01 (TA = 25°C, unless otherwise indicated) Boost Pull-Up Current vs Bus Capacitance 60 Rp = 2kΩ VCC = 5.5V 50 40 30 VCC = 3.3V 20 VCC = 2.5V 10 VCC = 1.8V 0 0 1000 2000 3000 4000 CAPACITANCE (pF) 5000 4311 G02 RP = 4.7kΩ CBUS = 1nF VCC = 5.5V 0 –40 –20 Supply Current vs Temperature 210 200 SUPPLY CURRENT (μA) 190 180 170 160 150 140 VCC = 1.8V 0 60 40 20 TEMPERATURE (°C) 80 100 4311 G03 Rise Time vs Capacitance 300 VCC = 1.8V 250 VCC = 3.3V RISE TIME (ns) VCC = 2.5V VCC = 5.5V VCC = 3.3V BUS1 = BUS2 = 0V 200 150 VCC = 5.5V 100 50 0 0 1000 2000 3000 4000 CAPACITANCE (pF) 5000 4311 G04 VCC = 2.5V RP = 2kΩ Measured from 0.3 • VCC to 0.7 • VCC 130 –40 –20 Standby Current vs Temperature 30 28 STANDBY CURRENT (μA) 26 24 22 20 18 VCC = 1.8V 16 –40 –20 40 20 60 0 TEMPERATURE (°C) 80 100 4311 G05 Bus Input Threshold Voltage vs Supply Voltage 0.8 0.75 VCC = 5.5V INPUT THRESHOLD (V) VCC = 2.5V 0.7 0.65 0.6 0.55 0.5 0.45 0.4 1 2 3 4 SUPPLY VOLTAGE (V) 5 6 4311 G06 VCC = 3.3V 4311fa 4 LTC4311 PIN FUNCTIONS BUS1: Active Pull-up for Bus. Connect to either clock line or data line for 2-wire bus. BUS2: Active Pull-up for Bus. Connect to either clock line or data line for 2-wire bus. ENABLE: Device Enable Input. This is a 1V nominal digital threshold input pin. For normal operation drive ENABLE to a voltage greater than 1.5V. Driving ENABLE below the 0.4V threshold puts the device in a low (