50ppm/°C Precision Micropower Shunt Voltage

References with Multiple Reverse Breakdown Voltages

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11

Detailed Description

The LM4050/LM4051 shunt references use the

bandgap principle to produce a stable, accurate volt-

age. The device behaves similarly to an ideal zener

diode; a fixed voltage is maintained across its output

terminals when biased with 60µA to 15mA of reverse

current. The LM4050/LM4051 clamps to a voltage of

one diode drop below ground when biased with for-

ward currents up 10mA.

Figure 3 shows a typical operating circuit. The

LM4050/LM4051 are ideal for providing stable refer-

ences from a high-voltage power supply.

Applications Information

The LM4050/LM4051s’ internal pass transistors are used

the necessary amount of current across a source resistor.

equation:

Choosing a larger resistance minimizes the total power dis-

sipation in the circuit by reducing the shunt current

incorporate the worst-case tolerance of the resistor used.

Ensure that the resistor’s power rating is adequate, using

the following general power equation:

Output Capacitance

The LM4050/LM4051 do not require external capacitors

for frequency stability and are stable for any output

capacitance.

Temperature Performance

The LM4050/LM4051 typically exhibit output voltage

temperature coefficients within ±15ppm/°C. The polari-

ty of the temperature coefficients may be different from

one device to another; some may have positive coeffi-

cients, and others may have negative coefficients.

High Temperature Operation

The maximum junction temperature of the LM4050/

LM4051 is +150°C. The maximum operating temperature

for the LM4050/LM4051_E_ is +125°C. At a maximum

load current of 15mA and a maximum output voltage of

5V, the parts dissipate 75mW of power. The power dissi-

pation limits of the 3-pin SC70 call for a derating value of

2.17mW/°C above +70°C and thus for 75mW of power

dissipation, the parts self-heat to 35.56°C above ambient

temperature. If the ambient temperature is +125°C, the

parts operate at 159.56°C, thereby exceeding the maxi-

mum junction temperature value of +150°C. For high-

temperature operation, care must be taken to ensure the

combination of ambient temperature, output power dissi-

pation, and package thermal resistance does not con-

spire to raise the device temperature beyond that listed

in the Absolute Maximum Ratings. Either reduce the out-

put load current or the ambient temperature to keep the

part within the limits.

Figure 3. Typical Operating Circuit

LM4050

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 connected to pin 2.

Chip Information

TRANSISTOR COUNT: 60

PROCESS: BiCMOS