MAX6138B データシートの表示（PDF） - Maxim Integrated

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MAX6138B

0.1%, 25ppm, SC70 Shunt Voltage Reference with Multiple Reverse Breakdown Voltages

Maxim Integrated 

0.1%, 25ppm, SC70 Shunt Voltage Reference

with Multiple Reverse Breakdown Voltages

Pin Description

PIN

NAME

FUNCTION

1

+

Positive Terminal of the Shunt Reference

2

-

Negative Terminal of the Shunt Reference

3

N.C.

No Connection. Leave this pin unconnected or connect to Pin 2.

Detailed Description

The MAX6138 shunt reference uses the bandgap prin-

ciple to produce a stable, accurate voltage. The device

behaves similarly to an ideal zener diode; a fixed volt-

age is maintained across its output terminals when

biased with 60µA to 15mA of reverse current. The

MAX6138 behaves similarly to a silicon diode when

biased with forward currents up to 10mA.

Figure 3 shows a typical operating circuit. The

MAX6138 is ideal for providing a stable reference from

a high-voltage power supply.

Applications Information

The MAX6138’s internal pass transistor is used to main-

tain a constant output voltage (VSHUNT) by sinking the

necessary amount of current across a source resistor.

The source resistance (RS) is determined from the load

current (ILOAD) range, supply voltage (VS) variations,

VSHUNT, and desired quiescent current.

Choose the value of RS when VS is at a minimum and

ILOAD is at a maximum. Maintain a minimum ISHUNT of

60µA at all times. The RS value should be large enough

to keep ISHUNT less than 15mA for proper regulation

when VS is maximum and ILOAD is at a minimum. To

prevent damage to the device, ISHUNT should never

exceed 20mA.

Therefore, the value of RS is bounded by the following

equation:

[VS(MIN) - VR] / [60µA + ILOAD(MAX)] > RS >

[VS(MAX) - VR] / [20mA + ILOAD(MIN)]

Choosing a larger resistance minimizes the total power

dissipation in the circuit by reducing the shunt current

(PD(TOTAL) = VS X ISHUNT). Provide a safety margin to

incorporate the worst-case tolerance of the resistor

used. Ensure that the resistor’s power rating is ade-

quate, using the following general power equation:

PDR = ISHUNT ✕ (VS(MAX) - VSHUNT)

VS

RS

ISHUNT

ISHUNT + ILOAD

ILOAD

VR

MAX6138

Figure 3. Typical Operating Circuit

Output Capacitance

The MAX6138 does not require an external capacitor

for operational stability and is stable for any output

capacitance.

Temperature Performance

The MAX6138 typically exhibits an output voltage tem-

perature coefficient within ±4ppm/°C. The polarity of

the temperature coefficient may be different from one

device to another; some may have positive coefficients,

and others may have negative coefficients.

Chip Information

TRANSISTOR COUNT: 70

PROCESS: BiCMOS

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