MAXIM MAX6330_05

19-1348; Rev 1; 12/05
Precision Shunt Regulators with Reset
in SOT23-3
____________________________Features
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 protecting µPs from power-up, power-down, and brownout
conditions.
♦ 100µA to 50mA Shunt Current Range
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 reduction in board space and improves reliability compared
to multiple-IC/discrete solutions. These devices have a
minimum order increment of 2,500 pieces.
♦ Precision Power-On Reset Threshold:
1.5% Tolerance Available with Either
RESET (MAX6331) or RESET (MAX6330)
Outputs
♦ Low Cost
♦ 3-Pin SOT23 Package
♦ ±1.5% Tolerance on Output Voltage
♦ Three Shunt Voltages Available: 5V, 3.3V, 3.0V
♦ 140ms Reset Timeout Period—No External
Components Required
_______________Ordering Information
________________________Applications
Controllers
Household Appliances
Intelligent Instruments
Critical µP and µC Power Monitoring
Portable/Size-Sensitive Equipment
PART*
TEMP. RANGE
PIN-PACKAGE
MAX6330_UR-T
MAX6331_UR-T
-40°C to +85°C
-40°C to +85°C
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 minimum order increment of 2,500 pieces.
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
Automotive
SOT
RESET
SHUNT
TOP MARK
SUFFIX THRESHOLD REGULATOR
(V)
VOLTAGE (V) MAX6330 MAX6331
____________Typical Operating Circuit
VIN
RS
IIN
VSHUNT
4.63
3.06
5.0
3.3
EKAA
EMAA
ELAA
ENAA
S
2.78
3.0
EDAA
EPAA
___________________Pin Configuration
ILOAD
TOP VIEW
CL
0.1µF*
ISHUNT
L
T
VCC
SHUNT
GND 1
MAX6330
MAX6331
RESET
(RESET)
µP
RESET
INPUT
GND
MAX6330
MAX6331
GND
3
SHUNT
RESET 2
(RESET)
SOT23-3
*SEE THE SECTION CHOOSING THE BYPASS CAPACITOR (CL)
( ) ARE FOR THE MAX6331
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
1
MAX6330/MAX6331
________________General Description
MAX6330/MAX6331
Precision Shunt Regulators with Reset
in SOT23-3
ABSOLUTE MAXIMUM RATINGS
Terminal Voltage (with respect to GND),
All Pins Except SHUNT....................-0.3V to (VSHUNT + 0.3V)
Input Current (ISHUNT) ........................................................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
(ISHUNT = 1mA, CL = 0.1µF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MAX633_L
VSHUNT Regulation Voltage
(Note 1)
VSHUNT
ISHUNT =
0.1mA to
50mA
MAX633_T
MAX633_S
Minimum VSHUNT for which
RESET is Valid (MAX6330)
MIN
TYP
MAX
TA = +25°C
4.93
5.0
5.07
TA = -40°C to +85°C
4.85
TA = +25°C
3.25
TA = -40°C to +85°C
3.20
TA = +25°C
2.96
TA = -40°C to +85°C
2.91
TA = 0°C to +70°C
1.0
TA = -40°C to +85°C
1.2
VSHUNT Tempco
Minimum Shunt Current
(Note 2)
ISHUNT(min)
Maximum Shunt Current
(Note 3)
ISHUNT(max)
100
Reset Threshold Voltage
VTH
MAX633_T
MAX633_S
TA = +25°C
4.56
TA = -40°C to +85°C
4.50
TA = +25°C
3.01
TA = -40°C to +85°C
2.97
TA = +25°C
2.74
TA = -40°C to +85°C
2.70
Reset Threshold Tempco
VSHUNT to Reset Delay
Reset Pulse Width
2
5.15
3.3
3.35
3.40
3.0
100mV overdrive, CL = 15pF
100
V
3.04
3.09
V
40
ppm/°C
60
µA
50
MAX633_L
UNITS
4.63
mA
4.69
4.75
3.06
3.11
3.15
2.78
V
2.82
2.86
40
ppm/°C
20
µs
140
_______________________________________________________________________________________
200
ms
Precision Shunt Regulators with Reset
in SOT23-3
MAX6330/MAX6331
ELECTRICAL CHARACTERISTICS (continued)
(ISHUNT = 1mA, CL = 0.1µF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
ISINK = 3.2mA
ISINK = 1.2mA
RESET/RESET Output
Voltage Low (Note 4)
VOL
VOH
TYP
MAX
MAX6330T/S, VTH(min)
0.3
MAX6331T/S, VTH(max)
V
0.3
MAX6330, VSHUNT = 1.2V, ISINK = 50µA,
TA = -40°C to +85°C
0.3
ISOURCE = 500µA
MAX6331L, VTH(min)
MAX6330L, VTH(max)
MAX6331T/S, VTH(min)
MAX6330T/S, VTH(max)
MAX6331, 1.8V < VSHUNT < VTH(min),
ISOURCE = 150µA
UNITS
0.4
MAX6331L, VTH(max)
MAX6330, VSHUNT = 1V, ISINK = 50µA,
TA = 0°C to +70°C
ISOURCE = 800µA
RESET/RESET Output
Voltage High (Note 4)
MIN
MAX6330L, VTH(min)
0.8 x VSHUNT
0.8 x VSHUNT
V
0.8 x VSHUNT
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 circuit board. The TA = +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 VSHUNT.
Note 3: Maximum shunt current required for regulated VSHUNT.
Note 4: In a typical application where SHUNT serves as the system voltage regulator, note that both ISOURCE for VOH and ISINK for
VOL come from VSHUNT (see the Typical Operating Circuit).
_______________________________________________________________________________________
3
__________________________________________Typical Operating Characteristics
(Typical Operating Circuit, CL = 0.1µF, ILOAD = 0mA, TA = +25°C, unless otherwise noted.)
NORMALIZED SHUNT VOLTAGE
vs. TEMPERATURE
TA = +25°C
1.000
TA = -40°C
0.995
TA = +85°C
ISHUNT = 50mA
ISHUNT = 25mA
1.000
ISHUNT = 1mA
0.995
40
MAX6330 TOC5
MAX6330 TOC02
1.005
NORMALIZED SHUNT VOLTAGE
MAX6330 TOC01
1.005
SHUNT VOLTAGE OVERSHOOT
vs. BYPASS CAPACITANCE (CL)
SHUNT VOLTAGE OVERSHOOT (mV)
NORMALIZED SHUNT VOLTAGE
vs. SHUNT CURRENT
NORMALIZED SHUNT VOLTAGE
35
ISHUNT = 5mA TO 50mA
30
25
ISHUNT = 0.1mA TO 5mA
20
15
10
ISHUNT = 1mA TO 1mA
5
0.990
0.990
0.1
1
10
0
-40
50
-20
0
20
40
60
80
POWER-UP RESET TIMEOUT
vs. TEMPERATURE
1.005
1.000
0.995
0.990
MAX6330 TOC03
160
POWER-UP RESET TIMEOUT (ms)
MAX6330 TOC04
NORMALIZED RESET THRESHOLD
1.010
150
140
130
120
110
100
-40
-20
0
20
40
60
80
-40
-20
0
20
40
TEMPERATURE (°C)
TEMPERATURE (°C)
STABILITY BOUNDARY CONDITIONS
START-UP TRANSIENT
MAX6330 TOC06
50
RECOMMENDED
CAPACITOR
OPERATING
REGION
UNSTABLE REGION
40
20
0.1
LOAD CAPACITANCE (µF)
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE
30
0.0047 0.01
TEMPERATURE (°C)
SHUNT CURRENT (mA)
RS = 15kΩ
VIN
50V/div
RECOMMENDED
CAPACITOR
VSHUNT
2V/div
RECOMMENDED
CAPACITANCE
10
60
0
1
0.001
0.01
0.1
1
LOAD CAPACITANCE (µF)
4
_______________________________________________________________________________________
80
MAX6330 TOC07
0.01
SHUNT CURRENT (mA)
MAX6330/MAX6331
Precision Shunt Regulators with Reset
in SOT23-3
1
Precision Shunt Regulators with Reset
in SOT23-3
PIN
NAME
FUNCTION
MAX6330 MAX6331
1
1
GND
Ground
2
—
RESET
Inverting Reset Output. RESET remains low while VSHUNT is below the reset threshold and
for 140ms after VSHUNT rises above the threshold.
—
2
RESET
Noninverting Reset Output. RESET remains high while VSHUNT is below the reset threshold
and for 140ms after VSHUNT rises above the threshold.
3
3
SHUNT
Regulated Shunt Voltage (+5V, +3.3V, or +3.0V)
_______________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 VSHUNT >
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 (VSHUNT dips below the
reset threshold), RESET goes low. When VSHUNT falls
below the reset threshold, the internal timer resets to
zero and RESET goes low. The internal timer starts after
VSHUNT 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 RS:
1) The input voltage range, (VIN)
2) The regulated voltage, (VSHUNT)
3) The output current range, (ILOAD)
Choose RS as follows:
(VIN(max) - VSHUNT (min)) / (50mA + ILOAD(min)) ≤ RS ≤
(VIN(min) - VSHUNT (max)) / (100µA + ILOAD(max))
Choose the largest nominal resistor value for RS that
gives the lowest current consumption. Provide a safety
margin to incorporate the worst-case tolerance of the
IIN
RS
VSHUNT
ILOAD
VIN
ISHUNT
CL
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 regulating the desired output voltage within a ±1.5% tolerance. The shunt current range (ISHUNT) is 100µA to
50mA.
The pass transistor in the MAX6330/MAX6331 maintains a constant output voltage (VSHUNT) by sinking the
necessary amount of shunt current. When ILOAD (see
Typical Operating Circuit) is at a maximum, the shunt
current is at a minimum, and vice versa:
IIN = ISHUNT + ILOAD = (VIN - VSHUNT) / RS
RESET
GENERATOR
140ms
TIMEOUT
RESET
(RESET)
MAX6330
MAX6331
1.2V
GND
( ) ARE FOR MAX6331
Figure 1. Functional Diagram
_______________________________________________________________________________________
5
MAX6330/MAX6331
______________________________________________________________Pin Description
PR = IIN(VIN(max) - VSHUNT)
= I2INRS
= (VIN(max) - VSHUNT)2 / RS
_____________Applications Information
ILOAD
2mA/div
IIN = 2mA, ILOAD = 0 to 1.9mA
VSHUNT IS AC COUPLED
MAX6330 FIG 02
resistor used. Ensure that the resistor’s power rating is
adequate, using the following general power equation:
0
Negative-Going VSHUNT Transients
Choosing the Bypass Capacitor, CL
0
VSHUNT
20mV/div
Figure 2. Load-Transient Response with CL = 0.22µF
The bypass capacitor (CL) on the SHUNT pin can significantly affect the device’s load-transient response, so
choose it carefully. When a load transient occurs, the
current for this load is diverted from the shunt regulator.
The maximum load current that can be diverted from
the regulator is:
ILOAD
2mA/div
ILOAD (diverted from regulator)
= ISHUNT(max) - ISHUNT(min)
= 50mA - 100µA
= 49.9mA
The shunt regulator has a finite response to this transient. The instantaneous requirements of the load
change are met by the charge on CL, resulting in overshoot/undershoot on VSHUNT. The magnitude of this
overshoot/undershoot increases with I SHUNT and
decreases with C L. When V SHUNT undershoots, the
shunt current decreases to where it will only draw quiescent current (IQ), and the shunt element turns off. At
this point, VSHUNT will slew toward VIN at the following
rate:
∆VSHUNT / ∆t = (IIN - ILOAD - 60µA) / CL
As VSHUNT rises, it will turn on the shunt regulator when
it can sink 100µA of current. A finite response time for
the shunt regulator to start up will result in a brief overshoot of VSHUNT before it settles into its regulation voltage. Therefore, ILOAD should always be 100µA or more
below IIN, or VSHUNT will not recover to its regulation
point. To prevent this condition, be sure to select the
correct series-resistor R S value (see the Shunt
Regulator section).
0
Figures 2, 3, and 4 show load-transient responses for
different choices of bypass capacitors on V SHUNT .
These photos clearly illustrate the benefits and drawbacks of the capacitor options. A smaller bypass
6
IIN = 2mA, ILOAD = 0 to 1.9mA,
VSHUNT IS AC COUPLED
MAX6330 FIG 03
In addition to issuing a reset to the µP during power-up,
power-down, and brownout conditions, the MAX6330/
MAX6331 are relatively immune to short-duration negative-going V SHUNT transients (glitches). Additional
bypass filter capacitance mounted close to the SHUNT
pin provides additional transient immunity.
0
VSHUNT
20mV/div
Figure 3. Load-Transient Response with CL = 0.033µF
ILOAD
2mA/div
IIN = 2mA, ILOAD = 0 to 1.9mA
VSHUNT IS AC COUPLED
MAX6330 FIG 04
MAX6330/MAX6331
Precision Shunt Regulators with Reset
in SOT23-3
0
0
VSHUNT
20mV/div
Figure 4. Load-Transient Response with CL = 0.0047µF
_______________________________________________________________________________________
Precision Shunt Regulators with Reset
in SOT23-3
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 resistor 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.
If the compensation of the bypass capacitor chosen is
insufficient, the output (VSHUNT) can oscillate. Before
choosing a bypass capacitor for the desired shunt current, 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.
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 output 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.
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 difference 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 overcome this condition and add hysteresis (Figure 5).
Interfacing to µPs with
Bidirectional Reset Pins
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 V SHUNT and V TH 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
RS
CL
TO OTHER SYSTEM
COMPONENTS
VSHUNT
VIN
RHYST
100k
CL
VCC
SHUNT
VCC
SHUNT
µP
MAX6330
RESET
MAX6330
MAX6331
RESET
INPUT
4.7k
µP
RESET
(RESET)
GND
GND
GND
GND
( ) ARE FOR MAX6331
Figure 5. Adding Hysteresis to the MAX6330
Figure 6. Interfacing to µPs with Bidirectional Reset I/O
_______________________________________________________________________________________
7
MAX6330/MAX6331
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.
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
SOTPO3L.EPS
MAX6330/MAX6331
Precision Shunt Regulators with Reset
in SOT23-3
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
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© 2005 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products, Inc.