LP5523 datasheet(51/61 Pages) TI2

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LP5523

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SNVS550E – SEPTEMBER 2009 – REVISED JANUARY 2017

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8.2.1.2 Detailed Design Procedure

8.2.1.2.1

Recommended External Components

The LP5523 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) always use multi-layer ceramic capacitors. These capacitors are small,

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

Ω typical). Ceramic capacitors with

X7R or X5R temperature characteristic are preferred for use with the LP5523. 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 LP5523. 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 LP5523.

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 TI recommends having at least 0.50 µF of effective capacitance for CIN and COUT under all operating

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

Table 8 lists recommended external components from some leading ceramic capacitor manufacturers. It is

strongly recommended that the LP5523 circuit be thoroughly evaluated early in the design-in process with the

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

impact circuit performance.

Table 8. Recommended External Components

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

of two

Panasonic

10V

0504

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

User defined. Note that D7, D8 and D9 outputs are powered from VDD when

specifying the LEDs.

LP5523 Datasheet(PDF) 51 Page - Texas Instruments

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