L99LD21 datasheet(12/73 Pages) STMICROELECTRONICS

12 / 73 page

Introduction

L99LD21

12/73

DS11130 Rev 5

LX2S

Kelvin connection to the switching source node of the buck2. This pin

has to be connected to external bootstrap capacitance.

BUCKIN2

Connection to the input of the buck channel 2

CBOOT2

Connection to the bootstrap capacitor (100nF) of the buck channel 2.

22, 38

PGND

Power Ground connection.

VLED2

Connection to the anode of the LED string for read back of the forward

voltage of the channel 2.

VLED1

Connection to the anode of the LED string for read back of the forward

voltage of the channel 1.

LX1F

Connection to the switching source node of the buck1. This pin must be

connected to external free-wheeling diode.

LX1S

Kelvin connection to the switching source node of the buck1. This pin

has to be connected to external bootstrap capacitance.

BUCKIN1

Connection to the input of the buck channel 1.

CBOOT1

Connection to the bootstrap capacitor (100 nF) of the buck channel 1.

Input supply pin of the IC. Connect VS to the battery voltage.

V5V

Output of the 5V regulated internal supply. Connect a low ESR capacitor

(4.7 µF) close to this pin.

Output of the boost gate driver for the external switching mosfet.

Positive connection to the boost shunt resistor, in series to the boost

switching mosfet.

Negative connection (Ground) to the boost shunt resistor, in series to the

boost switching mosfet.

COMP

Output of the error amplifier of the boost controller. Connect the

compensation network between this pin and SGND.

Boost output voltage feedback. Connect the FB pin to the boost output

voltage, via a resistor divider.

11, 12, 13,

14, 15, 19,

21, 27, 29,

33, 36

Not connected

Table 1. Pin functionality (continued)

Pin #

Name

Function

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