MAX4374TESD-T Maxim Integrated, MAX4374TESD-T Datasheet - Page 11

• Manufacturer Part Number: MAX4374TESD-T
• Description: Current Sense Amplifiers uPower High-Side Current-Sense Amp
• Manufacturer: Maxim Integrated
• Series: MAX4373, MAX4374, MAX4375r

Figure 3. MAX4375 Window Detector
It is recommended that V
at least a 0.1µF ceramic capacitor to isolate the IC from
supply voltage transients. It is possible that plugging
in/out a battery or AC adapter/charger could cause
large, fast line transients (>5V/µs) at V
solution is to run V
(+5V for example), since V
have to be connected together.
For high-speed V
add a resistor in series with the V
capacitor to create an RC time constant to slow the rise
time of the transient. Since these current-sense ampli-
fiers consume less than 100µA, even a 2.5kΩ resistor
only drops an extra 250mV at V
tions with fast transients, 1kΩ in conjunction with a
0.1µF bypass capacitor works well.
V
CC
(UP TO 5V)
Low-Cost, Micropower, High-Side Current-Sense
V
= 2.7V TO 28V
PULL-UP
V
IN
= 0 TO 28V
GND
R3
CC
______________________________________________________________________________________
V
COUT1
COUT2
RESET
CC
CC
transients, another solution is to
Amplifier + Comparator + Reference ICs
RS+
from a better regulated supply
Power-Supply Bypassing
MAX4375
+ V
CC
R
GND
CC
SENSE
SENSE
be bypassed to GND with
and RS+ (or RS-) do not
-
RS-
CC
CIN2
CIN1
CC
OUT
. For most applica-
CC
I
pin and a 0.1µF
LOAD
. The simplest
R1
R2
LOAD
R5
R4
The RESET pin is used to control the latch function of
comparator 1. Holding RESET low (<0.8V) makes the
latch transparent and COUT1 will respond to changes
at CIN1, above and below the internal 600mV reference
threshold voltage. When RESET is high (>2.0V), once
CIN1 rises above 600mV, COUT1 latches into the
open-drain OFF state and remains in this state even if
CIN1 drops below 600mV. Pulsing RESET low for at
least 1.5µs resets the latch.
There is no internal circuitry to control the reset function
during power-up. To prevent false latching, RESET
must be held low until the V
the 2.7V minimum operating supply voltage. This is
easily accomplished when RESET is driven under µC or
logic gate control. However, if RESET is to be always
connected high, add an RC between V
GND (see Figure 2). Note that RESET cannot exceed
V
The following formula can be used to determine the
appropriate RC value.
where T is the maximum time for V
0.8V is the maximum RESET logic low voltage. For
example, a 470kΩ resistor and 0.22µF capacitor will
keep RESET low during a power-up time of up to 36ms.
A faster power-up time is also safe with the calculated
R and C since the capacitor will have even less time to
charge.
CC
+ 0.3V or +12V, whichever is less.
RC
=
ln .
(
2 7
V
/( .
2 7
T
V
−
CC
0 8
RESET at Power-Up
.
power has risen above
V
)
CC
)
=
to reach 2.7V and
0 3514
.
CC
T
, RESET and
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