Datasheet MAX6330SUR-T, MAX6330TUR-T, MAX6330LUR-T, MAX6331LUR-T, MAX6331SUR-T Datasheet (Maxim)

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________________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 pro­tecting 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 reduc­tion in board space and improves reliability compared
to multiple-IC/discrete solutions. These devices have a
minimum order increment of 2,500 pieces.

________________________Applications

Controllers
Household Appliances
Intelligent Instruments
Critical µP and µC Power Monitoring
Portable/Size-Sensitive Equipment
Automotive

____________________________Features

♦ 100µA to 50mA Shunt Current Range
♦ Low Cost
♦ 3-Pin SOT23 Package
♦ ±1.5% Tolerance on Output Voltage
♦ Three Shunt Voltages Available: 5V, 3.3V, 3.0V
♦ Precision Power-On Reset Threshold:

1.5% Tolerance Available with Either
RESET (MAX6331) or

RESET (MAX6330)

Outputs

♦ 140ms Reset Timeout Period—No External

Components Required

MAX6330/MAX6331

Precision Shunt Regulators with Reset

in SOT23-3

________________________________________________________________

Maxim Integrated Products

1

TOP VIEW

RESET

(RESET)

1

GND

( ) ARE FOR THE MAX6331

SHUNT

MAX6330
MAX6331

SOT23-3

2

3

___________________Pin Configuration

____________Typical Operating Circuit

MAX6330
MAX6331

SHUNT

V

SHUNT

I

SHUNT

I

LOAD

V

IN

RESET

(RESET)

RESET
INPUT

GND

V

CC

CL

0.1µF*

GND

µP

*SEE THE SECTION

CHOOSING THE BYPASS CAPACITOR (CL)

I

IN

R

S

19-1348; Rev 0; 4/98

PART*

MAX6330_UR-T
MAX6331_UR-T

-40°C to +85°C

-40°C to +85°C

TEMP. RANGE PIN-PACKAGE

3 SOT23-3
3 SOT23-3

_______________Ordering Information

*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.

SUFFIX

L
T 3.06

4.63

RESET

THRESHOLD

(V)

EKAA

EMAA3.3

5.0

SHUNT
REGULATOR
VOLTAGE (V)

SOT

TOP MARK

ELAA

ENAA

S 3.02.78 EDAA EPAA

MAX6330 MAX6331

MAX6330/MAX6331

Precision Shunt Regulators with Reset
in SOT23-3

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(I

SHUNT

= 1mA, CL= 0.1µF, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°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.

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

MAX633_L

TA= 0°C to +70°C
TA= -40°C to +85°C

100mV overdrive, CL= 15pF

CONDITIONS

ms100 140 200Reset Pulse Width

µs20V

SHUNT

to Reset Delay

3.25 3.3 3.35

4.85 5.15
V

4.93 5.0 5.07

V

SHUNT

Regulation Voltage

(Note 1)

ppm/°C40Reset Threshold Tempco

V

4.56 4.63 4.69

V

TH

Reset Threshold Voltage

mA50I

SHUNT(max)

Maximum Shunt Current
(Note 3)

µA100 60I

SHUNT(min)

Minimum Shunt Current
(Note 2)

V

1.0

Minimum V

SHUNT

for which

RESET is Valid (MAX6330)

1.2
ppm/°C40V

SHUNT

Tempco

UNITSMIN TYP MAXSYMBOLPARAMETER

V

SHUNT

2.91 3.09

2.96 3.0 3.04

3.20 3.40

TA= -40°C to +85°C

TA= +25°C

TA= +25°C
TA= -40°C to +85°C
TA= +25°C
TA= -40°C to +85°C

TA= +25°C
TA= -40°C to +85°C

I

SHUNT

=

0.1mA to
50mA

4.50 4.75

2.97 3.15

MAX633_T

TA= +25°C
TA= -40°C to +85°C

3.01 3.06 3.11

2.70 2.86

MAX633_S

TA= +25°C
TA= -40°C to +85°C

2.74 2.78 2.82

MAX633_L

MAX633_T

MAX633_S

MAX6330/MAX6331

Precision Shunt Regulators with Reset

in SOT23-3

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(I

SHUNT

= 1mA, CL= 0.1µF, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)

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 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 VOHand I

SINK

for

V

OL

come from V

SHUNT

(see the

Typical Operating Circuit

).

CONDITIONS UNITSMIN TYP MAXSYMBOLPARAMETER

I

SINK

= 1.2mA

MAX6330T/S, V

TH

(min)

I

SINK

= 3.2mA

MAX6330, V

SHUNT

= 1V, I

SINK

= 50µA,

TA= 0°C to +70°C

0.3

MAX6330L, V

TH

(min)

0.3

MAX6331L, V

TH

(max)

MAX6331T/S, V

TH

(max)

0.4

V

OL

RESET/RESET Output
Voltage Low (Note 4)

MAX6330, V

SHUNT

= 1.2V, I

SINK

= 50µA,

TA= -40°C to +85°C

0.3

V

I

SOURCE

= 500µA

MAX6331T/S, V

TH

(min)

I

SOURCE

= 800µA

MAX6331, 1.8V < V

SHUNT

< V

TH(min)

,

I

SOURCE

= 150µA

0.8 x V

SHUNT

MAX6331L, V

TH

(min)

0.8 x V

SHUNT

MAX6330L, V

TH

(max)

MAX6330T/S, V

TH

(max)

0.8 x V

SHUNT

V

OH

RESET/RESET Output
Voltage High (Note 4)

V

MAX6330/MAX6331

Precision Shunt Regulators with Reset
in SOT23-3

4 _______________________________________________________________________________________

0.990

0.995

1.000

1.005

0.01 10.1 10 50

NORMALIZED SHUNT VOLTAGE

vs. SHUNT CURRENT

MAX6330 TOC01

SHUNT CURRENT (mA)

NORMALIZED SHUNT VOLTAGE

TA = +85°C

TA = -40°C

TA = +25°C

0.990

0.995

1.000

1.005

-40 0-20 20 40 60 80

NORMALIZED SHUNT VOLTAGE

vs. TEMPERATURE

MAX6330 TOC02

TEMPERATURE (°C)

NORMALIZED SHUNT VOLTAGE

I

SHUNT

= 50mA

I

SHUNT

= 25mA

I

SHUNT

= 1mA

100

110

120

130

150

140

160

-40 0-20 20 40 60 80

POWER-UP RESET TIMEOUT

vs. TEMPERATURE

MAX6330 TOC03

TEMPERATURE (°C)

POWER-UP RESET TIMEOUT (ms)

0.990

0.995

1.005

1.000

1.010

-40 0-20 20 40 60 80

NORMALIZED RESET THRESHOLD

vs. TEMPERATURE

MAX6330 TOC04

TEMPERATURE (°C)

NORMALIZED RESET THRESHOLD

VIN

50V/div

V

SHUNT

2V/div

0

START-UP TRANSIENT

MAX6330 TOC07

RS = 15kΩ

0

0.0047 10.10.01

SHUNT VOLTAGE OVERSHOOT

vs. BYPASS CAPACITANCE (C

L

)

15

5

35

25

40

20

10

30

MAX6330 TOC5

LOAD CAPACITANCE (µF)

SHUNT VOLTAGE OVERSHOOT (mV)

I

SHUNT

= 5mA TO 50mA

I

SHUNT

= 0.1mA TO 5mA

I

SHUNT

= 1mA TO 1mA

50

1

0.001 10.10.01

STABILITY BOUNDARY CONDITIONS

10

20

30

40

MAX6330 TOC06

LOAD CAPACITANCE (µF)

SHUNT CURRENT (mA)

UNSTABLE REGION

RECOMMENDED

CAPACITOR
OPERATING

REGION

RECOMMENDED

CAPACITANCE

RECOMMENDED

CAPACITOR

__________________________________________Typical Operating Characteristics

(Typical Operating Circuit, CL= 0.1µF, I

LOAD

= 0mA, TA= +25°C, unless otherwise noted.)

MAX6330/MAX6331

Precision Shunt Regulators with Reset

in SOT23-3

_______________________________________________________________________________________ 5

______________________________________________________________Pin Description

PIN

FUNCTION

1 1 Ground

2 —

Inverting Reset Output. RESET remains low while V

SHUNT

is below the reset threshold and

for 140ms after V

SHUNT

rises above the threshold.

—

2

Noninverting Reset Output. RESET remains high while V

SHUNT

is below the reset threshold

and for 140ms after V

SHUNT

rises above the threshold.

3 3 Regulated Shunt Voltage (+5V, +3.3V, or +3.0V)

NAME

GND

RESET

RESET

SHUNT

MAX6331MAX6330

_______________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.

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 (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:

IIN= I

SHUNT

+ I

LOAD

= (VIN- V

SHUNT

) / R

S

Consider the following information when choosing the
external resistor RS:

1) The input voltage range, (V

IN)

2) The regulated voltage, (V

SHUNT

)

3) The output current range, (I

LOAD)

Choose RSas follows:

(V

IN(max)

- V

SHUNT (min)

) / (50mA + I

LOAD(min)

) ≤ RS≤

(V

IN(min)

- V

SHUNT (max)

) / (100µA + I

LOAD(max)

)

Choose the largest nominal resistor value for RSthat
gives the lowest current consumption. Provide a safety
margin to incorporate the worst-case tolerance of the

MAX6330
MAX6331

V

IN

RSV

SHUNT

I

LOAD

I

SHUNT

I

IN

C

L

SHUNT

RESET

GENERATOR

140ms

TIMEOUT

RESET

(RESET)

1.2V

GND

( ) ARE FOR MAX6331

Figure 1. Functional Diagram

MAX6330/MAX6331

Precision Shunt Regulators with Reset
in SOT23-3

6 _______________________________________________________________________________________

resistor used. Ensure that the resistor’s power rating is
adequate, using the following general power equation:

PR= IIN(V

IN(max)

- V

SHUNT

)

= I

2

INRS

= (V

IN(max)

- V

SHUNT

)2/ R

S

_____________Applications Information

Negative-Going V

SHUNT

Transients

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.

Choosing the Bypass Capacitor, C

L

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:

I

LOAD

(diverted from regulator)

= I

SHUNT(max)

- I

SHUNT(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 V

SHUNT

. The magnitude of this

overshoot/undershoot increases with I

SHUNT

and

decreases with CL. 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, V

SHUNT

will slew toward VINat the following

rate:

∆V

SHUNT

/ ∆t = (IIN- I

LOAD

- 60µA) / C

L

As V

SHUNT

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 V

SHUNT

before it settles into its regulation volt-

age. Therefore, I

LOAD

should always be 100µA or more

below IIN, or V

SHUNT

will not recover to its regulation
point. To prevent this condition, be sure to select the
correct series-resistor RSvalue (see the

Shunt

Regulator

section).

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

I

LOAD

2mA/div

V

SHUNT

20mV/div

0

0

MAX6330 FIG 02

IIN = 2mA, I

LOAD

= 0 to 1.9mA

V

SHUNT

IS AC COUPLED

Figure 2. Load-Transient Response with CL= 0.22µF

I

LOAD

2mA/div

V

SHUNT

20mV/div

0

0

MAX6330 FIG 03

IIN = 2mA, I

LOAD

= 0 to 1.9mA,

V

SHUNT

IS AC COUPLED

Figure 3. Load-Transient Response with CL= 0.033µF

I

LOAD

2mA/div

V

SHUNT

20mV/div

0

0

MAX6330 FIG 04

IIN = 2mA, I

LOAD

= 0 to 1.9mA

V

SHUNT

IS AC COUPLED

Figure 4. Load-Transient Response with CL= 0.0047µF

MAX6330/MAX6331

Precision Shunt Regulators with Reset

in SOT23-3

_______________________________________________________________________________________ 7

capacitor allows a sharper drop in V

SHUNT

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 (V

SHUNT

) 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.

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 V

SHUNT

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).

Note that adding this pull-up resistor to the MAX6330 will
render RESET invalid with V

SHUNT

< 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 V

SHUNT

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 out­put and the µP reset I/O (Figure 6). Buffer the RESET
output to other system components. Also, RSmust be
sized to compensate for additional current drawn by
the µP during the fault condition.

Shunt Current Effects

on V

SHUNT

and V

TH

When sinking large shunt currents, power dissipation
heats the die to temperatures greater than ambient.
This may cause the V

SHUNT

and VTHtolerances 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.

MAX6330

SHUNT

V

IN

RESET

RESET
INPUT

R

HYST

100k

C

L

R

S

GND

V

CC

GND

µP

Figure 5. Adding Hysteresis to the MAX6330

MAX6330
MAX6331

SHUNT

V

IN

RESET

(RESET)

TO OTHER SYSTEM
COMPONENTS

C

L

4.7k

RSV

SHUNT

GND

V

CC

GND

µP

( ) ARE FOR MAX6331

Figure 6. Interfacing to µPs with Bidirectional Reset I/O

___________________Chip Information

TRANSISTOR COUNT: 283

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.

8

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© 1998 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

SOTPO3L.EPS

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