ADR3412/ADR3420/ADR3425/ADR3430/ADR3433/ADR3440/ADR3450

Rev. B | Page 18 of 24

TERMINOLOGY

Dropout voltage, sometimes referred to as supply voltage

headroom or supply-output voltage differential, is defined as

the minimum voltage differential between the input and output

such that the output voltage is maintained to within 0.1%

accuracy.

Because the dropout voltage depends upon the current passing

through the device, it is always specified for a given load current.

In series-mode devices, dropout voltage typically increases

proportionally to load current (see Figure 8 and Figure 14).

The temperature coefficient relates the change in output voltage

to the change in ambient temperature of the device, as normalized

by the output voltage at 25°C. This parameter is expressed in

ppm/°C and can be determined by the following equation:

]

/

[

10

)

(

)

(

)}

,

,

(

min{

)}

,

,

(

max{

6

1

3

2

3

2

1

3

2

1

C

ppm

T

T

T

V

T

T

T

V

T

T

T

V

TCV

OUT

OUT

OUT

OUT

°

×

−

×

−

=

(1)

where:

portrays the maximum difference between any of the three

temperatures at which the output voltage of the part is

measured.

ADR3440/ADR3450 is guaranteed via statistical means. This is

accomplished by recording output voltage data for a large

individual device via Equation 1, then defining the maximum

six standard deviations (6σ).

Thermally induced output voltage hysteresis represents the

change in output voltage after the device is exposed to a

specified temperature cycle. This is expressed as either a shift in

voltage or a difference in ppm from the nominal output.

TC

OUT

OUT

HYS

OUT

V

C

V

V

_

_

)

25

(

−

°

=

Δ

[V]

6

_

_

10

)

25

(

)

25

(

×

°

−

°

=

Δ

C

V

V

C

V

V

OUT

TC

OUT

OUT

HYS

OUT

[ppm]

where:

Long-term stability refers to the shift in output voltage at 50°C

after 1000 hours of operation in a 50°C environment. Ambient

temperature is kept at 50°C to ensure that the temperature

chamber does not switch randomly between heating and cooling,

which can cause instability over the 1000 hour measurement.

This is also expressed as either a shift in voltage or a difference

in ppm from the nominal output.

)

(

)

(

0

1

_

t

V

t

V

V

OUT

OUT

LTD

OUT

−

=

Δ

[V]

6

0

0

1

_

10

)

(

)

(

)

(

×

−

=

Δ

t

V

t

V

t

V

V

OUT

OUT

OUT

LTD

OUT

[ppm]

where:

at 50°C.

Line Regulation

Line regulation refers to the change in output voltage in response

to a given change in input voltage and is expressed in percent

per volt, ppm per volt, or μV per volt change in input voltage.

This parameter accounts for the effects of self-heating.

Load Regulation

Load regulation refers to the change in output voltage in

response to a given change in load current and is expressed in

μV per mA, ppm per mA, or ohms of dc output resistance. This

parameter accounts for the effects of self-heating.

Solder Heat Resistance (SHR) Drift

SHR drift refers to the permanent shift in output voltage

induced by exposure to reflow soldering, expressed in units of

ppm. This is caused by changes in the stress exhibited upon the

die by the package materials when exposed to high tempera-

tures. This effect is more pronounced in lead-free soldering

processes due to higher reflow temperatures.