MAX919ESA+ Maxim Integrated Products, MAX919ESA+ Datasheet - Page 10

• Manufacturer Part Number: MAX919ESA+
• Description: IC COMPARATOR BTR 8-SOIC
• Manufacturer: Maxim Integrated Products
• Series: Beyond-the-Rails™r
• Type: General Purposer

Specifications of MAX919ESA+

• Number Of Elements: 1
• Output Type: CMOS, Push-Pull, Rail-to-Rail, TTL
• Voltage - Supply: 1.8 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Number Of Channels: 1 Channel
• Product: Analog Comparators
• Offset Voltage (max): 10 mV
• Input Bias Current (max): 2 nA
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 1.8 V
• Supply Current (max): 0.8 uA
• Maximum Power Dissipation: 471 mW
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

SOT23, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference
The MAX917–MAX920 contain a unique break-before-
make output stage capable of rail-to-rail operation with
up to ±8mA loads. Many comparators consume orders
of magnitude more current during switching than dur-
ing steady-state operation. However, with this family of
comparators, the supply-current change during an out-
put transition is extremely small. In the Typical Oper-
ating Characteristics, the Supply Current vs. Output
Transition Frequency graphs show the minimal supply-
current increase as the output switching frequency
approaches 1kHz. This characteristic reduces the need
for power-supply filter capacitors to reduce glitches
created by comparator switching currents. In battery-
powered applications, this characteristic results in a
substantial increase in battery life.
The internal reference in the MAX917/MAX918 has an
output voltage of +1.245V with respect to V
cal temperature coefficient is 95ppm/°C over the full
-40°C to +85°C temperature range. The reference is a
PNP emitter-follower driven by a 120nA current source
(Figure 1). The output impedance of the voltage refer-
ence is typically 200kΩ, preventing the reference from
driving large loads. The reference can be bypassed
with a low-leakage capacitor. The reference is stable
for any capacitive load. For applications requiring a
lower output impedance, buffer the reference with a
low-input-leakage op amp, such as the MAX406.
The MAX917–MAX920 are ideally suited for use with most
battery-powered systems. Table 1 lists a variety of battery
types, capacities, and approximate operating times for
the MAX917–MAX920, assuming nominal conditions.
Table 1. Battery Applications Using MAX917–MAX920
10
Nickel-Cadmium
Nickel-Metal-
Lithium-Ion
BATTERY
(2 Cells)
______________________________________________________________________________________
Alkaline
(2 Cells)
(2 Cells)
Hydride
(1 Cell)
TYPE
Low-Voltage, Low-Power Operation
Applications Information
Reference (MAX917/MAX918)
RECHARGEABLE
Yes
Yes
Yes
No
Output Stage Circuitry
V
FRESH
(V)
3.0
2.4
3.5
2.4
EE
. Its typi-
V
END-OF-LIFE
(V)
1.8
1.8
2.7
1.8
Many comparators oscillate in the linear region of oper-
ation because of noise or undesired parasitic feed-
back. This tends to occur when the voltage on one
input is equal or very close to the voltage on the other
input. The MAX917–MAX920 have internal hysteresis to
counter parasitic effects and noise.
The hysteresis in a comparator creates two trip points:
one for the rising input voltage (V
falling input voltage (V
between the trip points is the hysteresis (V
the comparator’s input voltages are equal, the hystere-
sis effectively causes one comparator input to move
quickly past the other, thus taking the input out of the
region where oscillation occurs. Figure 2 illustrates the
case in which IN- has a fixed voltage applied, and IN+
is varied. If the inputs were reversed, the figure would
be the same, except with an inverted output.
Figure 1. MAX917/MAX918 Voltage Reference Output
Equivalent Circuit
CAPACITY,
AA SIZE
(mA-h)
2000
1000
1000
750
OPERATING TIME
MAX917/MAX918
120nA
1.25 x 10
1.25 x 10
2.5 x 10
937,500
THF
(hr)
V
CC
) (Figure 2). The difference
6
6
6
V
EE
Internal Hysteresis
THR
OPERATING TIME
MAX919/MAX920
) and one for the
REF
1.875 x 10
2.5 x 10
2.5 x 10
5 x 10
(hr)
HB
). When
6
6
6
6