LP5569ARTWR datasheet(79/93 Pages) TI2

79 / 93 page

VIN

AGND

SCL

SDA

LED0

LED1

LED2

LED3

EN/PWM

CLK

GPIO/TRIG/INT

ADDR

LED4

LED5

LED6

LED7

LED8

C1–

C1+

VOUT

COUT

CFLY1

1 µF

CIN

1 µF

µC

VIN = 2.5 V to 4.5 V, 3.6V typ

C2–

CFLY2

1 µF

V1P8

PGND

DC/DC

VIN

3 x AA

LP5569

www.ti.com

SNVSAP8A – JULY 2017 – REVISED SEPTEMBER 2017

Product Folder Links: LP5569

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Typical Applications (continued)

Figure 119. LP5569 Typical Application

9.2.1.1 Design Requirements

DESIGN PARAMETER

EXAMPLE VALUE

Input voltage range

2.5 V to 5.5 V

LED VF (maximum)

3.2 V

LED current

25.5 mA maximum

Input capacitor

CIN = 1 µF

Output capacitor

COUT = 1 µF

Charge pump flying capacitors

CFLY1 = CFLY2 = 1 µF

Charge-pump mode

1.5× or automatic

9.2.1.2 Detailed Design Procedure

The LP5569 device requires four external capacitors for proper operation. TI recommends surface-mount multi-

layer ceramic capacitors. Tantalum and aluminum capacitors are not recommended because of their high ESR.

Multi-layer ceramic capacitors must always be used for the flying capacitors (CFLY1 and CFLY2). Ceramic

capacitors with an X7R or X5R temperature characteristic are preferred for use with the LP5569 device. 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).

It is necessary to have at least 0.24 μF of effective capacitance for each of the flying capacitors under all

operating conditions to ensure proper operation. 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-ripple magnitude. For proper

operation TI recommends having at least 0.5 μF of effective capacitance for CIN and COUT under all operating

conditions. The voltage rating of all four capacitors must be 6.3 V (minimum), with 10 V preferred.

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