MAX6138 Maxim Integrated Products, MAX6138 Datasheet - Page 11

• Manufacturer Part Number: MAX6138
• Description: SC70 Shunt Voltage Reference
• Manufacturer: Maxim Integrated Products

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.
The MAX6138’s internal pass transistor is used to main-
tain a constant output voltage (V
necessary amount of current across a source resistor.
The source resistance (R
current (I
V
Choose the value of R
I
60µA at all times. The R
to keep I
when V
prevent damage to the device, I
exceed 20mA.
Therefore, the value of R
equation:
Choosing a larger resistance minimizes the total power
dissipation in the circuit by reducing the shunt current
(P
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:
LOAD
SHUNT
D(TOTAL)
[V
PIN
is at a maximum. Maintain a minimum I
0.1%, 25ppm, SC70 Shunt Voltage Reference
1
2
3
S
, and desired quiescent current.
S(MIN)
[V
LOAD
SHUNT
is maximum and I
PD
S(MAX
with Multiple Reverse Breakdown Voltages
= V
R
= I
- V
) range, supply voltage (V
S
Applications Information
less than 15mA for proper regulation
X I
SHUNT ✕
R
) - V
______________________________________________________________________________________
] / [60µA + I
SHUNT
R
Detailed Description
S
] / [20mA + I
NAME
S
N.C.
when V
S
S
value should be large enough
+
-
) is determined from the load
(V
). Provide a safety margin to
is bounded by the following
LOAD
S(MAX)
LOAD(MAX)
S
SHUNT
SHUNT
is at a minimum and
is at a minimum. To
LOAD(MIN)
- V
Positive Terminal of the Shunt Reference
Negative Terminal of the Shunt Reference
No Connection. Leave this pin unconnected or connect to Pin 2.
SHUNT
) by sinking the
] > R
should never
S
) variations,
)
]
S
SHUNT
>
of
The MAX6138 does not require an external capacitor
for operational stability and is stable for any output
capacitance.
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.
TRANSISTOR COUNT: 70
PROCESS: BiCMOS
Figure 3. Typical Operating Circuit
FUNCTION
I
SHUNT
R
S
V
Temperature Performance
S
I
SHUNT
Chip Information
I
LOAD
MAX6138
Output Capacitance
+ I
Pin Description
LOAD
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V
R
11