ZSLS7025 Datasheet

© 2016 Integrated Device Technology, Inc.

3

April 20, 2016

Contents

1

IC Characteristics .......................................................................................................................................................... 5

1.1

Absolute Maximum/Minimum Ratings.................................................................................................................... 5

1.2

Operating Conditions ............................................................................................................................................. 5

1.3

Electrical Parameters............................................................................................................................................. 6

1.4

Typical Performance Characteristics Graphs......................................................................................................... 7

2

Circuit Description ......................................................................................................................................................... 9

2.1

ZSLS7025 Overview .............................................................................................................................................. 9

2.2

Boost Converter ..................................................................................................................................................... 9

2.3

Internal 5V Regulator ........................................................................................................................................... 10

2.4

Input Current ........................................................................................................................................................ 10

2.5

LED Current Control ............................................................................................................................................ 10

2.6

Dimming Control .................................................................................................................................................. 10

2.6.1

Dimming Control Using an External DC Control Signal ................................................................................ 11

2.6.2

Dimming Control Using an RC Filter to Convert a PWM Signal to a DC Voltage.......................................... 12

2.6.3

PWM Dimming with a Dimming Control MOSFET (Q2)................................................................................. 13

2.7

Peak Input Current Control .................................................................................................................................. 13

2.8

Setting the Minimum Off-Time tOFF_MIN ................................................................................................................. 14

2.9

Switching Frequency and Inductor Value............................................................................................................. 14

2.10

DC Power Loss .................................................................................................................................................... 15

3

Operating Conditions................................................................................................................................................... 16

3.1

Under-Voltage Lockout ........................................................................................................................................ 16

3.2

Over-Voltage Protection....................................................................................................................................... 16

4

Application Circuit Design............................................................................................................................................ 17

4.1

Applications.......................................................................................................................................................... 17

4.2

External Component Selection............................................................................................................................. 17

4.2.1

Series Resistor RVDD..................................................................................................................................... 17

4.2.2

Inductor L1 .................................................................................................................................................... 17

4.2.3

High Frequency Noise Filter Capacitor CVDD ................................................................................................ 18

4.2.4

Input Capacitor CIN ....................................................................................................................................... 18

4.2.5

Output Capacitor COUT for Reducing Output Ripple ...................................................................................... 18

4.2.6

Schottky Rectifier Diode D1........................................................................................................................... 18

4.2.7

External MOSFET Q1.................................................................................................................................... 18

4.3

Application Circuit Layout Requirements ............................................................................................................. 19

4.4

Application Example ............................................................................................................................................ 19

4.4.1

Selecting RVDD, CIN, and CVDD....................................................................................................................... 20

4.4.2

Selecting RTOFF to Set Minimum tOFF............................................................................................................. 20

4.4.3

Selecting RFB to Set Output Current and C3................................................................................................. 20

4.4.4

Selecting R3, R4, R5 and C1 .......................................................................................................................... 21

4.4.5

RCS for Setting Input Peak Current ............................................................................................................... 22

4.4.6

L1 for Setting the Frequency ......................................................................................................................... 22

4.4.7

R1 and R2 for Setting OVP ............................................................................................................................ 23

4.4.8

Q1 External MOSFET and D1 Diode ............................................................................................................. 23

5

ESD Protection............................................................................................................................................................ 24