Data Sheet

ADR3625

TERMINOLOGY

analog.com

Rev. 0 | 13 of 21

Dropout Voltage

Dropout voltage (VDO), 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.

VDO = (VIN – VOUT)MIN|IL = Constant

Because VDO depends on the current passing through the device, it

is always specified for a given load current. In series mode devices,

the dropout voltage typically increases proportionally to the load

current (see Figure 6).

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.

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.

Solder Heat Resistance Shift

Solder heat resistance shift refers to the permanent shift in output

voltage that is induced by exposure to reflow soldering and is ex-

pressed as a percentage of the output voltage. This shift is caused

by changes in the stress exhibited on the die by the package

materials when these materials are exposed to high temperatures.

This effect is more pronounced in lead-free soldering processes

due to higher reflow temperatures. Solder heat resistance is calcu-

lated after three solder reflow cycles to simulate the worst case

conditions when assembling a two-sided PCB with surface-mount

components with one additional rework cycle. The reflow cycles use

the JEDEC standard reflow temperature profile.

Temperature Coefficient

The temperature coefficient (TCVOUT) relates the change in the

output voltage to the change in the ambient temperature of the

device, as normalized by the output voltage at 25°C. The TCVOUT

for the ADR3625 is fully tested over three temperatures: –40°C,

+25°C, and +125°C.

Box Method

The box method is represented by the following equation:

TCVOUT=

maxVOUTT1,T2,T3 −minVOUTT1,T2,T3

VOUTT2 × T3−T1

×106

where:

TCVOUT is expressed in ppm/°C.

VOUT(Tx) is the output voltage at temperature Tx.

T11 = –40°C.

T22 = +25°C.

T33 = +125°C.

This box method ensures that TCVOUT accurately portrays the

maximum difference between any of the three temperatures at

which the output voltage of the device is measured.

Thermal Hysteresis

Thermal hysteresis (ΔVOUT_HYS) represents the change in the out-

put voltage after the device is exposed to a specified temperature

cycle. ΔVOUT_HYS is expressed as a difference in ppm from the

nominal output.

ΔVOUT_HYS=VOUT1_25°C−VOUT2_25°C

VOUT1_25°C

×106ppm

where:

VOUT1_25°C is the output voltage at 25°C.

VOUT2_25°C is the output voltage after temperature cycling.

Long-Term Drift

Long-term drift (ΔVOUT_LTD) refers to the shift in the output voltage

vs. time. This is expressed as a difference in ppm from the nominal

output.

ΔVOUT_LTD= VOUTt1−VOUTt0

VOUTt0

×106ppm

where:

VOUT(t0) is the VOUT at the starting time of the measurement.

VOUT(t1) is the VOUT at the end time of the measurement.