MAX9005ESA+T Maxim Integrated Products, MAX9005ESA+T Datasheet - Page 15

• Manufacturer Part Number: MAX9005ESA+T
• Description: IC OP AMP LP HI SPEED 8-SOIC
• Manufacturer: Maxim Integrated Products
• Type: Amplifier, Comparatorr

Specifications of MAX9005ESA+T

• Applications: General Purpose
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

To add hysteresis, use the following procedure:
Step 1: The device’s input bias current can be as high
as 80nA. To minimize error due to the input bias,
choose a value for R2 of 100kΩ (V
allows a current of 12.33µA at the upper trip point.
Step 2: Choose the width of the hysteresis band. In this
example, choose 20mV for the added external hystere-
sis (V
V
where
Step 3: Determine R1. If V
Step 4: Check the hysteresis trip points. The following
equation represents the upper trip point (V
The lower trip point is 24mV lower than upper trip point.
V
The comparator’s propagation delay is a function of the
input overdrive voltage. Overdrive voltage is measured
from beyond the edge of the offset and hysteresis-
determined trip points (see Typical Operating
Characteristics for a graph of Propagation Delay vs.
Input Overdrive). High source impedance coupled with
the comparator’s input capacitance increases the prop-
agation delay. Large capacitive loads also increase the
propagation delay.
Shutdown is active-low enabled. The SHDN input for
the MAX9001/MAX9004 can be taken above the posi-
Figure 7. Enable/Disable Response of Op Amp, Comparator,
and Reference to SHDN
IHYST
IN(L)
V
R1 = R2 (V
IN(H)
5V/div
2V/div
5V/div
1V/div
SHDN
COUT
AOUT
VREF
EHYST
= 1.238V - 0.024V = 1.214V.
IHYST
= 24mV.
= [(R1 + R2) / R2] (V
A
V
= +1V/V, C
is the device’s internal hysteresis.
EHYST
= 20mV). Total hysteresis = V
Comparator Propagation Delay
AIN+
______________________________________________________________________________________
- 2V
= 2.5V, C
Op Amp + Comparator + Reference ICs
Low-Power, High-Speed, Single-Supply
IHYST
5 s/div
DD
CIN+
= 2.5V
REF
) / (V
= 5V, then R1 = 319Ω.
Shutdown
+ V
DD
IHYST
+ 2V
REF
IHYST
IN(H)
) = 1.238V
/ R2), which
EHYST
):
( S S H H D D N N )
)
+
tive supply without an increase in the SHDN input cur-
rent, allowing them to be driven from independent logic
circuits powered from a different supply voltage.
However, the logic threshold voltage requirements
must be met for proper operation. If SHDN is left
unconnected, the device defaults to the enabled mode
through an internal 4MΩ pull-up to V
be left unconnected, take proper care to ensure that no
signals are coupled to this pin, as this may cause false
triggering.
In shutdown mode, all outputs are set to a high-imped-
ance state and the supply current reduces to 2µA.
Enable times for the op amp, comparator, and refer-
ence are 2µs, 100ns, and 16µs, respectively. Shutdown
delay times for the op amp, comparator, and reference
are 200ns, 100ns, and 1µs, respectively (Figure 7).
Figure 8’s circuit is useful as a front end for RF alarms.
An unshielded inductor is used with capacitors C1A,
C1B, and C1C in a resonant circuit to provide frequen-
cy selectivity. The op amp from a MAX9003 amplifies
the signal received. The comparator improves noise
immunity, provides a signal-strength threshold, and
translates the received signal into a pulse train. The
tuned LC circuit in Figure 8 is set for 300kHz. The lay-
out and routing of components for the amplifier should
be tight to minimize 60Hz interference and crosstalk
from the comparator. Metal shielding is recommended
to prevent RFI from the comparator or digital circuitry
from exciting the receiving antenna. The transmitting
________________Application Circuits
Figure 8. Radio Receiver Application
ANTENNA
L1 x C1 =
L1
33 H
C1A
390pF
(2 f
1
C1B
0.01nF
C
)
2
50-100pF
C1C
0.1 F
Radio Receiver for Alarms
LAYOUT-SENSITIVE AREA,
METAL RFI SHIELDING ADVISED
5.1M
MAX9003
AMP
9.1k
10k
1.230V
and Detectors
DD
20k
0.1 F
. If SHDN is to
REF
V
CC
COMP
= 5V
10M
15