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MC79L00A

THREE–TERMINAL LOW CURRENT NEGATIVE FIXED VOLTAGE REGULATORS

Motorola => Freescale 

MC79L00, A Series

ELECTRICAL CHARACTERISTICS (VI = –33 V, IO = 40 mA, CI = 0.33 µF, CO = 0.1 µF, 0°C < TJ < +125°C, unless otherwise noted).

MC79L24C

MC79L24AC

Characteristics

Symbol

Min

Typ

Max

Min

Typ

Max Unit

Output Voltage (TJ = +25°C)

Input Regulation

(TJ = +25°C)

–27 Vdc ≥ VI ≥ –38 Vdc

–27.5 Vdc ≥ VI ≥ –38 Vdc

–28 Vdc ≥ VI ≥ –38 Vdc

Load Regulation

TJ = +25°C, 1.0 mA ≤ IO ≤ 100 mA

1.0 mA ≤ IO ≤ 40 mA

Output Voltage

–27 Vdc ≥ VI ≥ –38 V, 1.0 mA ≤ IO ≤ 40 mA

–28 Vdc ≥ VI ≥ –38 Vdc, 1.0 mA ≤ IO ≤ 40 mA

VI = –33 Vdc, 1.0 mA ≤ IO ≤ 70 mA

Input Bias Current

(TJ = +25°C)

(TJ = +125°C)

Input Bias Current Change

–28 Vdc ≥ VI ≥ –38 Vdc

1.0 mA ≤ IO ≤ 40 mA

Output Noise Voltage

(TA = +25°C, 10 Hz ≤ f ≤ 100 kHz)

VO

–22.1 –24 –25.9 –23

–24

–25

Vdc

Regline

mV

–

–

–

–

–

350

–

–

350

–

–

–

–

–

300

–

–

300

Regload

–

–

–

200

–

–

100

–

mV

–

200

–

100

VO

Vdc

–

–

–

–22.8

–

–25.2

–21.4

–

–26.4

–

–

–

–21.4

–

–26.4 –22.8

–

–25.2

IIB

mA

–

–

6.5

–

–

6.5

–

–

6.0

–

–

6.0

∆IIB

mA

–

–

1.5

–

–

1.5

–

–

0.2

–

–

0.1

Vn

–

200

–

–

200

–

µV

Ripple Rejection

(–29 ≤ VI ≤ –35 Vdc, f = 120 Hz, TJ = +25°C)

RR

30

43

–

31

47

–

dB

Dropout Voltage

IO = 40 mA, TJ = +25°C

|VI–VO|

–

1.7

–

–

1.7

–

Vdc

APPLICATIONS INFORMATION

Design Considerations

The MC79L00, A Series of fixed voltage regulators are

designed with Thermal Overload Protections that shuts down

the circuit when subjected to an excessive power overload

condition, Internal Short Circuit Protection that limits the

maximum current the circuit will pass.

In many low current applications, compensation

capacitors are not required. However, it is recommended that

the regulator input be bypassed with a capacitor if the

regulator is connected to the power supply filter with long wire

length, or if the output load capacitance is large. An input

bypass capacitor should be selected to provide good

high–frequency characteristics to insure stable operation

under all load conditions. A 0.33 µF or larger tantalum, mylar,

or other capacitor having low internal impedance at high

frequencies should be chosen. The bypass capacitor should

be mounted with the shortest possible leads directly across

the regulator’s input terminals. Normally good construction

techniques should be used to minimize ground loops and

lead resistance drops since the regulator has no external

sense lead. Bypassing the output is also recommended.

Figure 1. Positive and Negative Regulator

+Vin

0.33µF

MC78LXX

+VO

0.1µF

Figure 2. Standard Application

Input

CI*

0.33µF

MC79LXX

Output

CO**

0.1µF

–Vin

0.33µF

MC79LXX

0.1µF

–VO

A common ground is required between the input and the output

voltages. The input voltage must remain typically 2.0 V above

the output voltage even during the low point on the ripple voltage.

* CI is required if regulator is located an appreciable

* distance from the power supply filter

** CO improves stability and transient response.

4

MOTOROLA ANALOG IC DEVICE DATA

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