19-1348; Rev 0; 4/98
Precision Shunt Regulators with Reset
in SOT23-3
________________General Description
The MAX6330/MAX6331 combine a precision shunt
regulator with a power-on reset function in a single
SOT23-3 package. They offer a low-cost method of
operating small microprocessor (µP)-based systems
from high-voltage sources, while simultaneously pro-
tecting µPs from power-up, power-down, and brownout
conditions.
Both active-low (MAX6330) and active-high (MAX6331)
push/pull output versions are available. The output
voltage has ±1.5% tolerance. The MAX6330/MAX6331
operate over a wide shunt current range from 100µA to
50mA, and offer very good transient immunity.
A 3-pin SOT23 package allows for a significant reduc-
tion in board space and improves reliability compared
to multiple-IC/discrete solutions. These devices have a
minimum order increment of 2,500 pieces.
____________________________Features
o
100µA to 50mA Shunt Current Range
o
Low Cost
o
3-Pin SOT23 Package
o
±1.5% Tolerance on Output Voltage
o
Three Shunt Voltages Available: 5V, 3.3V, 3.0V
o
Precision Power-On Reset Threshold:
1.5% Tolerance Available with Either
RESET (MAX6331) or
RESET
(MAX6330)
Outputs
o
140ms Reset Timeout Period—No External
Components Required
MAX6330/MAX6331
________________________Applications
Controllers
Household Appliances
Intelligent Instruments
Critical µP and µC Power Monitoring
Portable/Size-Sensitive Equipment
Automotive
_______________Ordering Information
PART*
MAX6330_UR-T
MAX6331_UR-T
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
3 SOT23-3
3 SOT23-3
*Insert the desired suffix letter (from the table below) into the
blank to complete the part number. These devices have a mini-
mum order increment of 2,500 pieces.
SOT
RESET
SHUNT
TOP MARK
SUFFIX THRESHOLD REGULATOR
(V)
VOLTAGE (V) MAX6330 MAX6331
L
T
S
4.63
3.06
2.78
5.0
3.3
3.0
EKAA
EMAA
EDAA
ELAA
ENAA
EPAA
____________Typical Operating Circuit
V
IN
R
S
I
IN
V
SHUNT
I
SHUNT
SHUNT
I
LOAD
C
L
0.1µF*
V
CC
___________________Pin Configuration
TOP VIEW
MAX6330
MAX6331
RESET
(RESET)
GND
µP
RESET
INPUT
GND
1
MAX6330
MAX6331
GND
RESET
2
(RESET)
3
SHUNT
SOT23-3
*SEE THE SECTION
CHOOSING THE BYPASS CAPACITOR
(C
L
)
( ) ARE FOR THE MAX6331
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 408-737-7600 ext. 3468.
Precision Shunt Regulators with Reset
in SOT23-3
MAX6330/MAX6331
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND),
All Pins Except SHUNT....................-0.3V to (V
SHUNT
+ 0.3V)
Input Current (I
SHUNT
) ........................................................60mA
Output Current (RESET/RESET)..........................................20mA
Short-Circuit Duration.................................................Continuous
Continuous Power Dissipation
SOT23-3 (derate 4mW/°C above +70°C)....................320mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10sec) .............................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(I
SHUNT
= 1mA, C
L
= 0.1µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MAX633_L
V
SHUNT
Regulation Voltage
(Note 1)
V
SHUNT
I
SHUNT
=
0.1mA to
50mA
MAX633_T
MAX633_S
Minimum V
SHUNT
for which
RESET
is Valid (MAX6330)
V
SHUNT
Tempco
Minimum Shunt Current
(Note 2)
Maximum Shunt Current
(Note 3)
I
SHUNT(min)
I
SHUNT(max)
MAX633_L
Reset Threshold Voltage
V
TH
MAX633_T
MAX633_S
Reset Threshold Tempco
V
SHUNT
to Reset Delay
Reset Pulse Width
100mV overdrive, C
L
= 15pF
100
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
4.56
4.50
3.01
2.97
2.74
2.70
40
20
140
200
2.78
3.06
4.63
100
T
A
= 0°C to +70°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
T
A
= +25°C
T
A
= -40°C to +85°C
MIN
4.93
4.85
3.25
3.20
2.96
2.91
1.0
1.2
40
60
50
4.69
4.75
3.11
3.15
2.82
2.86
ppm/°C
µs
ms
V
3.0
3.3
TYP
5.0
MAX
5.07
5.15
3.35
3.40
3.04
3.09
V
ppm/°C
µA
mA
V
UNITS
2
_______________________________________________________________________________________
Precision Shunt Regulators with Reset
in SOT23-3
ELECTRICAL CHARACTERISTICS (continued)
(I
SHUNT
= 1mA, C
L
= 0.1µF, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SYMBOL
I
SINK
= 3.2mA
I
SINK
= 1.2mA
RESET/RESET Output
Voltage Low (Note 4)
V
OL
CONDITIONS
MAX6330L, V
TH(min)
MAX6331L, V
TH(max)
MAX6330T/S, V
TH(min)
MAX6331T/S, V
TH(max)
MIN
TYP
MAX
0.4
0.3
V
0.3
0.3
0.8 x V
SHUNT
0.8 x V
SHUNT
0.8 x V
SHUNT
V
UNITS
MAX6330/MAX6331
MAX6330, V
SHUNT
= 1V, I
SINK
= 50µA,
T
A
= 0°C to +70°C
MAX6330, V
SHUNT
= 1.2V, I
SINK
= 50µA,
T
A
= -40°C to +85°C
I
SOURCE
= 800µA
MAX6331L, V
TH(min)
MAX6330L, V
TH(max)
MAX6331T/S, V
TH(min)
MAX6330T/S, V
TH(max)
RESET/RESET Output
Voltage High (Note 4)
V
OH
I
SOURCE
= 500µA
MAX6331, 1.8V < V
SHUNT
< V
TH(min)
,
I
SOURCE
= 150µA
Note 1:
It is recommended that the regulation voltage be measured using a 4-wire force-sense technique when operating at high
shunt currents. For operating at elevated temperatures, the device must be derated based on a +150°C maximum allowed
junction temperature and a maximum thermal resistance of 0.25°C/mW junction to ambient when soldered on a printed cir-
cuit board. The T
A
= +25°C specification over load is measured using a pulse test at 50mA with less than 5ms on time.
Note 2:
Minimum shunt current required for regulated V
SHUNT
.
Note 3:
Maximum shunt current required for regulated V
SHUNT
.
Note 4:
In a typical application where SHUNT serves as the system voltage regulator, note that both I
SOURCE
for V
OH
and I
SINK
for
V
OL
come from V
SHUNT
(see the
Typical Operating Circuit).
_______________________________________________________________________________________
3
Precision Shunt Regulators with Reset
in SOT23-3
MAX6330/MAX6331
__________________________________________Typical Operating Characteristics
(Typical Operating Circuit, C
L
= 0.1µF, I
LOAD
= 0mA, T
A
= +25°C, unless otherwise noted.)
NORMALIZED SHUNT VOLTAGE
vs. SHUNT CURRENT
MAX6330 TOC01
NORMALIZED SHUNT VOLTAGE
vs. TEMPERATURE
MAX6330 TOC02
SHUNT VOLTAGE OVERSHOOT
vs. BYPASS CAPACITANCE (C
L
)
35
30
25
20
15
10
5
I
SHUNT
= 1mA TO 1mA
I
SHUNT
= 0.1mA TO 5mA
I
SHUNT
= 5mA TO 50mA
MAX6330 TOC5
1.005
NORMALIZED SHUNT VOLTAGE
1.005
I
SHUNT
= 50mA
NORMALIZED SHUNT VOLTAGE
I
SHUNT
= 25mA
1.000
I
SHUNT
= 1mA
0.995
40
SHUNT VOLTAGE OVERSHOOT (mV)
T
A
= +25°C
1.000
T
A
= -40°C
0.995
T
A
= +85°C
0.990
0.01
0.1
1
10
50
SHUNT CURRENT (mA)
0.990
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
0
0.0047 0.01
0.1
LOAD CAPACITANCE (µF)
1
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE
MAX6330 TOC04
POWER-UP RESET TIMEOUT
vs. TEMPERATURE
MAX6330 TOC03
1.010
NORMALIZED RESET THRESHOLD
160
POWER-UP RESET TIMEOUT (ms)
150
140
130
120
110
100
1.005
1.000
0.995
0.990
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
-40
-20
0
20
40
60
80
TEMPERATURE (°C)
STABILITY BOUNDARY CONDITIONS
MAX6330 TOC06
START-UP TRANSIENT
R
S
= 15kΩ
MAX6330 TOC07
50
RECOMMENDED
CAPACITOR
OPERATING
REGION
UNSTABLE REGION
40
SHUNT CURRENT (mA)
30
V
IN
50V/div
20
RECOMMENDED
CAPACITOR
10
RECOMMENDED
CAPACITANCE
V
SHUNT
2V/div
0
1
0.001
0.01
0.1
1
LOAD CAPACITANCE (µF)
4
_______________________________________________________________________________________
Precision Shunt Regulators with Reset
in SOT23-3
______________________________________________________________Pin Description
PIN
NAME
MAX6330 MAX6331
1
2
—
3
1
—
2
3
GND
RESET
RESET
SHUNT
Ground
Inverting Reset Output.
RESET
remains low while V
SHUNT
is below the reset threshold and
for 140ms after V
SHUNT
rises above the threshold.
Noninverting Reset Output. RESET remains high while V
SHUNT
is below the reset threshold
and for 140ms after V
SHUNT
rises above the threshold.
Regulated Shunt Voltage (+5V, +3.3V, or +3.0V)
FUNCTION
MAX6330/MAX6331
_______________Detailed Description
Reset Output
A microprocessor’s (µP’s) reset input starts the µP in a
known state. The MAX6330/MAX6331 µP supervisory
circuits assert reset to prevent code-execution errors
during power-up, power-down, or brownout conditions.
RESET
is guaranteed to be a logic low for V
SHUNT
>
1V. Once V
SHUNT
exceeds the reset threshold, an
internal timer keeps
RESET
low for the reset timeout
period; after this interval,
RESET
goes high.
If a brownout condition occurs (V
SHUNT
dips below the
reset threshold),
RESET
goes low. When V
SHUNT
falls
below the reset threshold, the internal timer resets to
zero and
RESET
goes low. The internal timer starts after
V
SHUNT
returns above the reset threshold, and
RESET
then remains low for the reset timeout period.
The MAX6331 has an active-high RESET output that is
the inverse of the MAX6330’s
RESET
output.
Consider the following information when choosing the
external resistor R
S
:
1) The input voltage range, (V
IN)
2) The regulated voltage, (V
SHUNT
)
3) The output current range, (I
LOAD)
Choose R
S
as follows:
(V
IN(max)
- V
SHUNT (min)
) / (50mA + I
LOAD(min)
)
≤
R
S
≤
(V
IN(min)
- V
SHUNT (max)
) / (100µA + I
LOAD(max)
)
Choose the largest nominal resistor value for R
S
that
gives the lowest current consumption. Provide a safety
margin to incorporate the worst-case tolerance of the
I
IN
V
IN
R
S
I
SHUNT
V
SHUNT
I
LOAD
C
L
SHUNT
Shunt Regulator
The shunt regulator consists of a pass device and a
controlling circuit, as illustrated in Figure 1. The pass
device allows the regulator to sink current while regu-
lating the desired output voltage within a ±1.5% toler-
ance. The shunt current range (I
SHUNT
) is 100µA to
50mA.
The pass transistor in the MAX6330/MAX6331 main-
tains a constant output voltage (V
SHUNT
) by sinking the
necessary amount of shunt current. When I
LOAD
(see
Typical Operating Circuit)
is at a maximum, the shunt
current is at a minimum, and vice versa:
I
IN
= I
SHUNT
+ I
LOAD
= (V
IN
- V
SHUNT
) / R
S
GND
( ) ARE FOR MAX6331
RESET
GENERATOR
140ms
TIMEOUT
RESET
(RESET)
MAX6330
MAX6331
1.2V
Figure 1. Functional Diagram
_______________________________________________________________________________________
5
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