S-818 datasheet(6/23 Pages) SII

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LOW DROPOUT CMOS VOLTAGE REGULATOR

Rev.1.2

S-818 Series

Seiko Instruments Inc.

Technical Terms

1. Low dropout voltage regulator

The low dropout voltage regulator is a voltage regulator having a low dropout voltage characteristic due to the

internal low on-resistance transistor.

2. Output voltage (VOUT)

The accuracy of the output voltage is ensured at

± 2.0% under the specified conditions of input voltage,

output current, and temperature, which differ product by product.

Note:

When the above conditions are changed, the output voltage may vary and go out of the accuracy range of

the output voltage. See the electrical characteristics and characteristic data for details.

3. Line regulations 1 and 2 (

∆VOUT1, ∆VOUT2)

Line regulation indicates the input voltage dependence of the output voltage. The value shows how much the

output voltage changes due to the change of the input voltage when the output current is kept constant.

4. Load regulation (

∆VOUT3)

Load regulation indicates the output current dependence of output voltage. The value shows how much the

output voltage changes due to the change of the output current when the input voltage is kept constant.

5. Dropout voltage (Vdrop)

Let VIN1 be an input voltage where the output voltage falls to the 98% of the actual output voltage VOUT(E)

when gradually decreasing input voltage. The dropout voltage is the difference between the VIN1 and the

resultant output voltage defined as following equation.

Vdrop = VIN1-[VOUT(E) × 0.98]

6. Temperature coefficient of output voltage [

∆V

OUT/(

∆Ta • V

OUT)]

The shadowed area in Figure 6 is the range where VOUT varies in the operating temperature range when the

temperature coefficient of the output voltage is

±100 ppm/°C.

-40

+0.28mV/

°C

VOUT

[V]

VOUT (E) is a mesured value of

output voltage at 25

°C.

OUT

(E)

Ta [

°C]

-0.28mV/

°C

Figure 6 Temperature coefficient range of output voltage

A change of output voltage in temperature [mV/°C] is calculated using the following equation.

∆VOUT

[ppm/

°C] ÷1000

[mV/

°C] = VOUT(S)[V] ×

∆Ta

∆VOUT

∆Ta • VOUT

Specified output voltage

Output voltage temperature coefficient

Change of output voltage in temperatures

Typical Example of the S-818A28A

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