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I am designing two linear power supplies that will:

  1. Drop 9V DC to 5V DC to power a Raspberry Pi around 2.5A
  2. Drop 9V DC to 7.5V DC to power a DAC under 3A

I plan to use Texas Instruments LDO UCC283-ADJTexas Instruments LDO UCC283-ADJ. An adjustable LDO.

I have been reading the datasheet:

http://www.ti.com/lit/pdf/slus215

Which advises (see page 5) that a timing capacitor, C, is required:

CT: Short-circuit timing capacitor and shutdown input for the UCC283−ADJ version. Pulling CT below 0.25 V turns off the regulator and places it in a low quiescent-current mode. A timing capacitor, C, from CT to GND programs the duration of the pulsed short-circuit on-time. On-time, tON, is approximately given by:

tON = 750 k * C

Whilst the formula is given, I am at a loss as to what size capacitor I should use as C, for each of my implementations.

I was planning R1 to be 50kOhms and R2 to be 10kOhms.

Can anyone advise me on C?

Thanks.

I am designing two linear power supplies that will:

  1. Drop 9V DC to 5V DC to power a Raspberry Pi around 2.5A
  2. Drop 9V DC to 7.5V DC to power a DAC under 3A

I plan to use Texas Instruments LDO UCC283-ADJ. An adjustable LDO.

I have been reading the datasheet:

http://www.ti.com/lit/pdf/slus215

Which advises (see page 5) that a timing capacitor, C, is required:

CT: Short-circuit timing capacitor and shutdown input for the UCC283−ADJ version. Pulling CT below 0.25 V turns off the regulator and places it in a low quiescent-current mode. A timing capacitor, C, from CT to GND programs the duration of the pulsed short-circuit on-time. On-time, tON, is approximately given by:

tON = 750 k * C

Whilst the formula is given, I am at a loss as to what size capacitor I should use as C, for each of my implementations.

I was planning R1 to be 50kOhms and R2 to be 10kOhms.

Can anyone advise me on C?

Thanks.

I am designing two linear power supplies that will:

  1. Drop 9V DC to 5V DC to power a Raspberry Pi around 2.5A
  2. Drop 9V DC to 7.5V DC to power a DAC under 3A

I plan to use Texas Instruments LDO UCC283-ADJ. An adjustable LDO.

I have been reading the datasheet:

http://www.ti.com/lit/pdf/slus215

Which advises (see page 5) that a timing capacitor, C, is required:

CT: Short-circuit timing capacitor and shutdown input for the UCC283−ADJ version. Pulling CT below 0.25 V turns off the regulator and places it in a low quiescent-current mode. A timing capacitor, C, from CT to GND programs the duration of the pulsed short-circuit on-time. On-time, tON, is approximately given by:

tON = 750 k * C

Whilst the formula is given, I am at a loss as to what size capacitor I should use as C, for each of my implementations.

I was planning R1 to be 50kOhms and R2 to be 10kOhms.

Can anyone advise me on C?

Thanks.

3 Used standard blockquote format for the quoted text. Used HTML list format for the power supply list. Other minor changes.
source | link

I am designing two linear power supplies that will:

1) drop 9v DC to 5v DC to power a raspberry pi around 2.5A 2) drop 9v DC to 7.5v DC to power a DAC under 3A

  1. Drop 9V DC to 5V DC to power a Raspberry Pi around 2.5A
  2. Drop 9V DC to 7.5V DC to power a DAC under 3A

I plan to use Texas Instruments LDO UCC283-ADJ. An adjustable LDO.

I have been reading the datasheet:

http://www.ti.com/lit/pdf/slus215

Which advises that a timing capacitor is required, C

"CT: Short-circuit timing capacitor and shutdown input for the UCC283−ADJ version. Pulling CT below 0.25 V turns off the regulator and places it in(see page 5) that a low quiescent-current mode. A timing capacitor, C, from CT to GND programs the duration of the pulsed short-circuit on-time. On-time, tON, is approximately given byrequired:

tON = 750 k * C"

CT: Short-circuit timing capacitor and shutdown input for the UCC283−ADJ version. Pulling CT below 0.25 V turns off the regulator and places it in a low quiescent-current mode. A timing capacitor, C, from CT to GND programs the duration of the pulsed short-circuit on-time. On-time, tON, is approximately given by:

tON = 750 k * C

Whilst the formula is given, I am at a loss as to what size capacitor I should use as C, for each of my implementations.

I was planning R1 to be 50kOhms and R2 to be 10kOhms.

Can anyone advise me on C?

Thanks.

I am designing two linear power supplies that will:

1) drop 9v DC to 5v DC to power a raspberry pi around 2.5A 2) drop 9v DC to 7.5v DC to power a DAC under 3A

I plan to use Texas Instruments LDO UCC283-ADJ. An adjustable LDO.

I have been reading the datasheet:

http://www.ti.com/lit/pdf/slus215

Which advises that a timing capacitor is required, C

"CT: Short-circuit timing capacitor and shutdown input for the UCC283−ADJ version. Pulling CT below 0.25 V turns off the regulator and places it in a low quiescent-current mode. A timing capacitor, C, from CT to GND programs the duration of the pulsed short-circuit on-time. On-time, tON, is approximately given by:

tON = 750 k * C"

Whilst the formula is given I am at a loss as to what size capacitor I should use as C, for each of my implementations.

I was planning R1 to be 50kOhms and R2 to be 10kOhms.

Can anyone advise me on C?

Thanks

I am designing two linear power supplies that will:

  1. Drop 9V DC to 5V DC to power a Raspberry Pi around 2.5A
  2. Drop 9V DC to 7.5V DC to power a DAC under 3A

I plan to use Texas Instruments LDO UCC283-ADJ. An adjustable LDO.

I have been reading the datasheet:

http://www.ti.com/lit/pdf/slus215

Which advises (see page 5) that a timing capacitor, C, is required:

CT: Short-circuit timing capacitor and shutdown input for the UCC283−ADJ version. Pulling CT below 0.25 V turns off the regulator and places it in a low quiescent-current mode. A timing capacitor, C, from CT to GND programs the duration of the pulsed short-circuit on-time. On-time, tON, is approximately given by:

tON = 750 k * C

Whilst the formula is given, I am at a loss as to what size capacitor I should use as C, for each of my implementations.

I was planning R1 to be 50kOhms and R2 to be 10kOhms.

Can anyone advise me on C?

Thanks.

2 deleted 1 character in body; edited title
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Variable LDO implementatioimplementation - capacitor size

I am designing two linear power supplies that will:

1) drop 9v DC to 5v DC to power a raspberry pi around 2.5A 2) drop 9v DC to 7.5v DC to power a DAC under 3A

I plan to use Texas Instruments LDO UCC283-ADJ. An adjustable LDO.

I have been reading the datasheet:

http://www.ti.com/lit/pdf/slus215

Which advises that a timing capacitor is required, C

"CT: Short-circuit timing capacitor and shutdown input for the UCC283−ADJ version. Pulling CT below 0.25 V turns off the regulator and places it in a low quiescent-current mode. A timing capacitor, C, from CT to GND programs the duration of the pulsed short-circuit on-time. On-time, tON, is approximately given by:

tON = 750 k * C"

Whilst the formula is given I am at a loss as to what size capacitor I should use as C, for each of my implementations.

I was planning R1 to be 50kOhms and R2 to be 10kOhms.

Can anyone advise me on C?

Thanks

Variable LDO implementatio - capacitor size

I am designing two linear power supplies that will:

1) drop 9v DC to 5v DC to power a raspberry pi around 2.5A 2) drop 9v DC to 7.5v DC to power a DAC under 3A

I plan to use Texas Instruments LDO UCC283-ADJ. An adjustable LDO.

I have been reading the datasheet:

http://www.ti.com/lit/pdf/slus215

Which advises that a timing capacitor is required, C

"CT: Short-circuit timing capacitor and shutdown input for the UCC283−ADJ version. Pulling CT below 0.25 V turns off the regulator and places it in a low quiescent-current mode. A timing capacitor, C, from CT to GND programs the duration of the pulsed short-circuit on-time. On-time, tON, is approximately given by:

tON = 750 k * C"

Whilst the formula is given I am at a loss as to what size capacitor I should use as C, for each of my implementations.

I was planning R1 to be 50kOhms and R2 to be 10kOhms.

Can anyone advise me on C?

Thanks

Variable LDO implementation - capacitor size

I am designing two linear power supplies that will:

1) drop 9v DC to 5v DC to power a raspberry pi around 2.5A 2) drop 9v DC to 7.5v DC to power a DAC under 3A

I plan to use Texas Instruments LDO UCC283-ADJ. An adjustable LDO.

I have been reading the datasheet:

http://www.ti.com/lit/pdf/slus215

Which advises that a timing capacitor is required, C

"CT: Short-circuit timing capacitor and shutdown input for the UCC283−ADJ version. Pulling CT below 0.25 V turns off the regulator and places it in a low quiescent-current mode. A timing capacitor, C, from CT to GND programs the duration of the pulsed short-circuit on-time. On-time, tON, is approximately given by:

tON = 750 k * C"

Whilst the formula is given I am at a loss as to what size capacitor I should use as C, for each of my implementations.

I was planning R1 to be 50kOhms and R2 to be 10kOhms.

Can anyone advise me on C?

Thanks

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