L99LD02 datasheet(13/66 Pages) STMICROELECTRONICS

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DS12448 Rev 3

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L99LD02

Boost controller

3.1

General description

The L99LD02 device is able to work both with a microcontroller and without it (stand-alone

operation).

The device integrates two boost controllers, based on a fixed frequency, peak current mode

architecture. It can drive the gates of up to two external n-channel MOSFETs in order to step

up the VS input voltage to a higher stabilized output voltage.

The L99LD02 integrates a 10V LDO to supply the gate drivers for standard level MOSFETs

and features a device supply option from boost output.

This features is implemented in order to avoid any operation of the external MOSFETs of the

boost controller in linear mode, due to a too low gate driver supply. On top of that, with

supply option from boost output, the device fulfills cold cranking requirements.

3.2

Switching frequency

The L99LD02 operates at a fixed frequency which can range from 100 kHz to 470 kHz. The

switching frequency is configurable via SPI (see CR#3 Bit[7:5], BST_FREQ in Table 24:

CR#3: Control Register 3) or through dedicated OTPs (for stand-alone configuration).

Boost operative switching frequency value can be set according to Table 2:

The L99LD02 features an internal dither oscillator. Frequency modulation as well as

deviation percentage can be programmed through SPI (see CR#3 Bit[11:10] BST_FDEV,

Bit[9:8] BST_FMOD in Table 24: CR#3: Control Register 3).

3.3

Output voltage

The boost output voltage (BST_OUT) can vary in the range [14.7÷80] V with a granularity of

7 bits.

Table 2. Switching frequency configuration

BITs [3÷0]

BST_FREQ [kHz]

000

101.01

001

151.52

010

196.08

011

256.41

100

303.03

101

333.33

110

416.67

111

476.19

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