MAX6330 View Datasheet(PDF) - Maxim Integrated
Part Name
Description
Manufacturer
MAX6330 Datasheet PDF : 8 Pages
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Precision Shunt Regulators with Reset
in SOT23-3
capacitor allows a sharper drop in VSHUNT when the
load transient occurs, and will suffer from a steeper
overshoot when the device re-enters regulation. On the
other hand, the increased compensation on a larger
bypass capacitor will lead to a longer recovery time to
regulation. The Typical Operating Characteristics graph
Overshoot vs. Bypass Capacitance (CL) illustrates this
trade-off.
If the compensation of the bypass capacitor chosen is
insufficient, the output (VSHUNT) can oscillate. Before
choosing a bypass capacitor for the desired shunt cur-
rent, observe the stability boundary conditions indicated
in the Typical Operating Characteristics. The minimum
output capacitance is 0.03µF to ensure stability over the
full load-current range.
Adding Hysteresis
In certain circumstances, the MAX6330 can be trapped
in a state that forces it to enter into and exit from a reset
condition indefinitely. This usually occurs in systems
where VSHUNT is just below the device’s trip threshold
and the system draws less quiescent current under reset
conditions than when operating out of reset. The differ-
ence in supply current when the device is in or out of
reset can translate to a significant change in the voltage
drop across RS, which the MAX6330’s built-in hysteresis
may not overcome. A 100kΩ pull-up resistor will over-
come this condition and add hysteresis (Figure 5).
Note that adding this pull-up resistor to the MAX6330 will
render RESET invalid with VSHUNT < 1V, since this output
loses sinking capability at this point, and the pull-up resis-
tor would invalidate the signal. This does not present a
problem in most applications, since most µPs and other
circuitry are inoperative when VSHUNT is below 1V.
Interfacing to µPs with
Bidirectional Reset Pins
Microprocessors with bidirectional reset pins (such as
the Motorola 68HC11 series) can contend with
MAX6330’s reset output. If, for example, the MAX6330’s
RESET output is asserted high and the µP wants to pull
it low, indeterminate logic levels may result. To correct
this, connect a 4.7kΩ resistor between the RESET out-
put and the µP reset I/O (Figure 6). Buffer the RESET
output to other system components. Also, RS must be
sized to compensate for additional current drawn by
the µP during the fault condition.
Shunt Current Effects
on VSHUNT and VTH
When sinking large shunt currents, power dissipation
heats the die to temperatures greater than ambient.
This may cause the VSHUNT and VTH tolerances to
approach ±3% at high ambient temperatures and high
shunt currents. Limit the die temperature to less than
+150°C using ΘJA = 0.25°C/mW.
___________________Chip Information
TRANSISTOR COUNT: 283
RS
VIN
CL
RHYST
100k
SHUNT
VCC
MAX6330
RESET
µP
RESET
INPUT
GND
GND
RS VSHUNT
VIN
CL
SHUNT
MAX6330
MAX6331
4.7k
RESET
(RESET)
GND
TO OTHER SYSTEM
COMPONENTS
VCC
µP
GND
Figure 5. Adding Hysteresis to the MAX6330
( ) ARE FOR MAX6331
Figure 6. Interfacing to µPs with Bidirectional Reset I/O
_______________________________________________________________________________________ 7
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