Datasheet LTC1540 (Analog Devices) - 6

LTC1540
PIN FUNCTIONS GND (Pin 1):
Ground. Connect to V– for single supply
V+ (Pin 7):
Positive Supply operating voltage is from 2V operation. to 11V.
V– (Pin 2):
Negative Supply. Potential should be more
OUT (Pin 8):
Comparator CMOS Output. Swings from negative than GND. Connect to ground for single supply GND to V+. Output can source up to 40mA and sink 5mA. operation.
IN+ (Pin 3)
: Noninverting Comparator Input. Input common mode range from V– to V+ – 1.3V. Input current typically 1 LTC1540 OUT 8 10pA at 25°C. GND
IN– (Pin 4):
Inverting Comparator Input. Input common 2 V– 7 V+ mode range from V– to V+ – 1.3V. Input current typically + 10pA at 25°C. 3 IN+ – REF 6
HYST (Pin 5):
Hysteresis Input. Connect to REF if not used. Input voltage range is from V 4 IN– 5 REF to VREF – 50mV. HYST
REF (Pin 6):
Reference Output. 1.182V with respect 1540 • PD to V–. Can source up to 1mA and sink 10µA at 25°C. Drive 0.01µF bypass capacitor without oscillation.
APPLICATIONS INFORMATION
The LTC1540 is a nanopower comparator with a built-in
Comparator Output
1.182V reference. Features include programmable hyster- The comparator output swings between GND and V+ to esis, wide supply voltage range (2V to 11V) and the ability assure TTL compatibility with a split supply. The output of the reference to drive up to a 0.01µF capacitor without is capable of sourcing up to 40mA and sinking up to 5mA oscillation. The comparator’s CMOS outputs can source while still maintaining nanoampere quiescent currents. up to 40mA while supply current glitches that normally The output stage does not generate crowbar switching occur when switching logic states, have been eliminated. currents during transitions which helps minimize parasitic
Power Supplies
feedback through the supply pins. The comparator operates from a single 2V to 11V supply.
Voltage Reference
The LTC1540 includes a separate ground for the compara- The internal bandgap reference has a voltage of 1.182V tor output stage, allowing a split supply ranging from ±1V referenced to V–. The reference accuracy is ±2.0% from to ±5.5V. Connecting V– to GND will allow single supply 0°C to 70°C. It can source up to 1mA and sink up to 10µA operation. If the comparator output is required to source with a 5V supply. The reference can drive a bypass capaci- more than 1mA, or the supply source impedance is high, tor of up to 0.01µF without oscillation and by inserting V+ should be bypassed with a 0.1µF capacitor. a series resistor, capacitance values up to 10µF can be
Comparator Inputs
used (Figure 1). The comparator inputs can swing from the negative supply, Figure 2 shows the resistor value required for different V–, to within 1.3V (max) of the positive supply V+. The capacitor values to achieve critical damping. Bypassing inputs can be forced 300mV below V– or above V+ without the reference can help prevent false tripping of the com- damage and the typical input leakage current is only ±10pA. parators by preventing glitches on V+ or reference load transients from disturbing the reference output voltage. 1540fb 6 For more information www.linear.com/LTC1540