Output-capacitor selection and regulator stability – Rainbow Electronics MAX15007 User Manual

Page 11

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MAX15006/MAX15007

40V, Ultra-Low Quiescent-Current

Linear Regulators in 6-Pin TDFN/8-Pin SO

______________________________________________________________________________________

11

Then determine the maximum output current:

Example 3 (TDFN Package):

T

A

= +50°C

V

IN

= 9V

V

OUT

= 5V

Calculate the maximum allowable package dissipation
at the given temperature as follows:

P

D

= 1.9048W

Find the maximum output current:

In Examples 2 and 3, the maximum output current is
calculated as 172mA and 476mA, respectively; howev-
er, the allowable output current cannot exceed 50mA.

Alternately, use Figures 5a and 5b to quickly determine
the maximum allowable output current for selected
ambient temperatures and input voltages.

Output-Capacitor Selection

and Regulator Stability

For stable operation over the full temperature range
and with load currents up to 50mA, use a low-ESR
2.2µF (min) ceramic or tantalum output capacitor. Use
larger output-capacitor values such as 22µF to reduce
noise, improve load-transient response, and power-
supply rejection.

Some ceramic dielectrics exhibit large capacitance
and ESR variations with temperature. Ensure the mini-
mum capacitance under worst-case conditions does
not drop below 1.3µF to ensure output stability. With an
X7R dielectric, 2.2µF should be sufficient at all operat-
ing temperatures.

I

1.9048W

9V 5V

476mA

OUT(MAX)

(

)

=

=

=

I

mA

OUT MAX

50

I

1.5478W

14V 5V

172mA

OUT(MAX)

(

)

=

=

=

I

mA

OUT MAX

50

MAX15006 fig05a

V

IN

(V)

I

OUT(MAX)

(mA)

35

30

20

25

10

15

5

5

10

15

20

25

30

35

40

45

50

55

60

0

0

40

T

A

= +85

°C

T

A

= +70

°C

T

A

= +125

°C

V

OUT

= 5V

6-PIN TDFN

Figure 5a. Calculated Maximum Output Current vs. Input
Voltage (6-Pin TDFN-EP)

MAX15006 fig05b

V

IN

(V)

I

OUT(MAX)

(mA)

35

30

20

25

10

15

5

5

10

15

20

25

30

35

40

45

50

55

60

0

0

40

T

A

= +85

°C

T

A

= +70

°C

T

A

= +125

°C

V

OUT

= 5V

8-PIN SO-EP

Figure 5b. Calculated Maximum Output Current vs. Input
Voltage (8-Pin SO-EP)

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