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LP8501

SNVS548D – SEPTEMBER 2008 – REVISED AUGUST 2013

www.ti.com

APPLICATIONS INFORMATION

Recommended External Components

The LP8501 requires 4 external capacitors for proper operation. Surface-mount multi-layer ceramic capacitors

are recommended. Tantalum and aluminium capacitors are not recommended because of their high ESR. For

the flying capacitors (C1 and C2) multi-layer ceramic capacitors should always be used. These capacitors are

small, inexpensive and have very low equivalent series resistance (ESR <20 m

Ω typ.). Ceramic capacitors with

X7R or X5R temperature characteristic are preferred for use with the LP8501. These capacitors have tight

capacitance tolerance (as good as ±10%) and hold their value over temperature (X7R: ±15% over

−55°C to

125°C; X5R: ±15% over

−55°C to 85°C). Capacitors with Y5V or Z5U temperature characteristic are generally

not recommended for use with the LP8501. Capacitors with these temperature characteristics typically have wide

capacitance tolerance (+80%,

−20%) and vary significantly over temperature (Y5V: +22%, -82% over −30°C to

+85°C range; Z5U: +22%,

−56% over +10°C to +85°C range). Under some conditions, a nominal 1 μF Y5V or

Z5U capacitor could have a capacitance of only 0.1

μF. Such detrimental deviation is likely to cause Y5V and

Z5U capacitors to fail to meet the minimum capacitance requirements of the LP8501.

For proper operation it is necessary to have at least 0.24 µF of effective capacitance for each of the flying

capacitors under all operating conditions. The output capacitor COUT directly affects the magnitude of the output

ripple voltage. In general, the higher the value of COUT, the lower the output ripples magnitude. For proper

operation it is necessary to have at least 0.50 µF of effective capacitance for CIN and COUT under all operating

conditions. The voltage rating of all four capacitors should be 6.3V; 10V is recommended.

The table below lists recommended external components from some leading ceramic capacitor manufacturers. It

is strongly recommended that the LP8501 circuit be thoroughly evaluated early in the design-in process with the

mass-production capacitors of choice. This will help ensure that any variability in capacitance does not negatively

impact circuit performance.

Model

Type

Vendor

Voltage Rating

Package Size

1 µF for COUT and CIN

C1005X5R1A105K

Ceramic X5R

TDK

10V

0402

LMK105BJ105KV-F

Ceramic X5R

Taiyo Yuden

10V

0402

ECJ0EB1A105M

Ceramic X5R

Panasonic

10V

0402

ECJUVBPA105M

Ceramic X5R, array

Panasonic

10V

0504

of two

470 nF for C1 and C2

C1005X5R1A474K

Ceramic X5R

TDK

10V

0402

LMK105BJ474KV-F

Ceramic X5R

Taiyo Yuden

10V

0402

ECJ0EB0J474K

Ceramic X5R

Panasonic

6.3V

0402

LEDs

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