Rainbow Electronics MAX9013 - Manual (Page 7)

MAX9010–MAX9013
SC70, 5ns, Low-Power, Single-Supply,
Precision TTL Comparators
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Detailed Description
These high-speed comparators have a unique design
that prevents oscillation when the comparator is in its
linear region, so no minimum input slew rate is required.
Many high-speed comparators oscillate in their linear
region. One common way to overcome this oscillation is
to add hysteresis, but it results in a loss of resolution
and bandwidth.
Latch Function
The MAX9011/MAX9013 provide a TTL-compatible latch
function that holds the comparator output state (Figure 1).
With LE driven to a TTL low or grounded, the latch is
transparent and the output state is determined by the
input differential voltage. When LE is driven to a TTL high,
the existing output state is latched, and the input differen-
tial voltage has no further effect on the output state.
Input Amplifier
A comparator can be thought of as having two sec-
tions: an input amplifier and a logic interface. The input
amplifiers of these devices are fully differential, with
input offset voltages typically 0.7mV at +25°C. Input
common-mode range extends from 200mV below
ground to 1.9V below the positive power-supply rail. The
total common-mode range is 3.3V when operating from a
5V supply. The amplifiers have no built-in hysteresis. For
highest accuracy, do not add hysteresis. Figure 2 shows
how hysteresis degrades resolution.
Input Voltage Range
Although the common-mode input voltage range is
restricted to -0.2V to (V
CC - 1.9V), either or both inputs
can go to either absolute maximum voltage limit, i.e.,
from -0.3V to (V
CC + 0.3V), without damage. The com-
parator will make a correct (and fast) logic decision
provided that at least one of the two inputs is within the
specified common-mode range. If both inputs are out-
side the common-mode range, the comparator output
state is indeterminate.
Resolution
A comparator’s ability to resolve a small-signal differ-
ence, its resolution, is affected by various factors. As
with most amplifiers and comparators, the most signifi-
cant factors are the input offset voltage (V
OS
) and the
common-mode and power-supply rejection ratios
(CMRR, PSRR). If source impedance is high, input off-
set current can be significant. If source impedance is
unbalanced, the input bias current can introduce
another error. For high-speed comparators, an addi-
PIN
MAX9010 MAX9011 MAX9012 MAX9013
NAME FUNCTION
1 1 — 7 OUT
Comparator Output. OUT is high when IN+ is more
positive than IN-.
2 2 5 6 GND Ground
3 3 — 2 IN+ Noninverting Input
4 4 — 3 IN- Inverting Input
5, 6 6 8 1 V CC
Positive Power-Supply Voltage. Pins 5 and 6 of the
MAX9010 must BOTH be connected to the power-
supply rail. Bypass with a 0.1µF capacitor.
— 5 — 5 LE Latch Enable Input
— — 1 — INA+ Noninverting Input, Channel A
— — 2 — INA- Inverting Input, Channel A
— — 3 — INB+ Noninverting Input, Channel B
— — 4 — INB- Inverting Input, Channel B
— — 6 — OUTB Comparator Output, Channel B
— — 7 — OUTA Comparator Output, Channel A
— — — 4 N.C.
No Connection. Not internally connected. Connect to
GND for best results.
— — — 8 OUT Comparator Complementary Output
Pin Description