Datasheet LTC1443, LTC1444, LTC1445 (Analog Devices) - 8

LTC1443/LTC1444/LTC1445
applicaTions inForMaTion
The LTC1443/LTC1444/LTC1445 is a family of quad
Voltage Reference
micropower comparators with a built-in reference (1.182V The internal bandgap reference has a voltage of 1.182V for for the LTC1443 and 1.221V for the LTC1444/LTC1445). LTC1443 or 1.221V for LTC1444/LTC1445 referenced to Features include programmable hysteresis (LTC1444/ V–. The reference accuracy is 1.5% from –40°C to 85°C. LTC1445), wide supply voltage range (2V to 11V) and the It can source up to 200µA and sink up to 15µA with a 5V ability of the reference to drive up to a 0.01µF capacitor with- supply. The reference can drive a bypass capacitor of up to out oscillation. The comparator CMOS outputs (LTC1443/ 0.01µF without oscil ation and by inserting a series resistor, LTC1445) can source up to 40mA while the LTC1444 has capacitance values up to 100µF can be used (Figure 1). an open-drain output to V–. The supply current glitches that normally occur when the comparator output switches states have been eliminated. REFERENCE OUTPUT REF
Power Supplies
R1 LTC144X The comparator family operates from a single 2V to 11V + 1.2V supply. The LTC1443 includes a separate ground for the C1 – comparator output stage, allowing a split supply ranging V– from ±1V to ±5.5V. Connecting V– to GND on the LTC1443 144345 F01 allows single supply operation. If the comparator output is required to source more than 1mA or the supply source
Figure 1. Damping the Reference Output
impedance is high, V+ should be bypassed with a 0.1µF capacitor. Figure 2 shows the resistor value required for different
Comparator Inputs
capacitor values to achieve critical damping. The comparator inputs can swing from the negative sup- 1000 ply (V–) to within 1.3V maximum of the positive supply (V+). The inputs can be forced 300mV below V– or above V+ without damage, and the typical input leakage current ) 100 Ω is only ±10pA. 10
Comparator Outputs
The LTC1443 comparator output swings between GND RESISTOR VALUE (k 1 and V+ to assure TTL compatibility with a split supply. The LTC1444 and LTC1445 outputs swing between V– 0.1 and V+. The outputs are capable of sourcing up to 40mA 0.001 0.01 0.1 1 10 (LTC1443/LTC1445) and sinking up to 5mA while still CAPACITOR VALUE (µF) 144345 F02 maintaining microampere quiescent currents. The output stage does not generate crowbar switching currents dur-
Figure 2. Damping Resistance vs Bypass Capacitor Value
ing transitions which helps minimize parasitic feedback through the supply pins. 144345fe 8 Document Outline Features Applications Description Absolute Maximum Ratings Typical Application Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Applications Information Package Description Revision History Typical Application Related Parts