MAX1574 Ver la hoja de datos (PDF) - Maxim Integrated

Número de pieza

componentes Descripción

Lista de partido

MAX1574

180mA, 1x/2x, White LED Charge Pump in 3mm x 3mm TDFN

Maxim Integrated 

180mA, 1x/2x, White LED Charge Pump

in 3mm x 3mm TDFN

Table 1. Recommended Components

COMPONENT

DESIGNATION

CIN, COUT

C1

D1, D2, D3

RSET

VALUE

1µF

0.22µF

0.47µF

—

As Required

MANUFACTURER PART NUMBER

DESCRIPTION

Taiyo Yuden

TDK

Taiyo Yuden

TDK

Taiyo Yuden

TDK

Nichia

Citizen

Kamaya

Panasonic

JMK107BJ105KA 1µF ±10%, 6.3V X5R ceramic capacitors (0603)

C1005X5R0J105M 1µF ±20%, 6.3V X5R ceramic capacitors (0402)

JMK105BJ224KV 0.22µF ±10%, 6.3V X5R ceramic capacitor (0402)

C1005X5R0J224K 0.22µF ±10%, 6.3V X5R ceramic capacitor (0402)

JMK105BJ474KV 0.47µF ±10%, 6.3V X5R ceramic capacitor (0402)

C1005X5R0J474K 0.47µF ±10%, 6.3V X5R ceramic capacitor (0402)

NSCW215T

White LEDs

CL-470S

White LED flash module

—

1% resistor

Applications Information

Driving Fewer than Three LEDs

When driving fewer than three LEDs, connect any unused

LED_ directly to IN (Figure 3). When connected in this

manner, the corresponding LED driver is disabled.

Driving Camera Strobes/Flashes

The MAX1574’s 180mA output capability makes it suit-

able for driving white LED camera strobes/flashes. For

example, the typical operating circuit drives a 3-LED

flash module with up to 60mA/LED. To ensure 180mA

total drive capability at low input voltages, increase C1

to 0.47µF.

To drive fewer or more LEDs with regulated total cur-

rent up to 180mA or to reduce the number of connect-

ing wires, short LED1, LED2, and LED3 together. When

connected this way, some LED modules have good

LED-to-LED forward-voltage matching, while others

may require individual ballast resistors. It is a good

idea to keep the ballast resistance as low as practical

for reasonable matching because high-ballast resis-

tance reduces the output drive capability due to the

higher VOUT requirement.

Input Ripple

For LED drivers, input ripple is more important than out-

put ripple. Input ripple depends on the source supply’s

impedance. Adding a lowpass filter to the input further

reduces input ripple. Alternatively, increasing CIN to

2.2µF cuts input ripple in half with only a small increase in

footprint. The 1x mode always has very low input ripple.

Component Selection

Use only ceramic capacitors with an X5R, X7R, or better

dielectric. See Table 1 for a list of recommended parts.

PC Board Layout and Routing

The MAX1574 is a high-frequency switched-capacitor

voltage regulator. For best circuit performance, use a

solid ground plane and place CIN, COUT, and C1 as

close to the MAX1574 as possible. Refer to the

MAX1574 evaluation kit for an example.

_______________________________________________________________________________________ 7

Share Link: