L99LD02 datasheet(16/66 Pages) STMICROELECTRONICS

16 / 66 page

Boost controller

L99LD02

16/66

DS12448 Rev 3

Both slope compensation and OTA gain are configurable via SPI (see CR#2 Bit[15:14],

BST_GM_OTA in Table 23: CR#2: Control Register 2) or through dedicated OTPs (for

stand-alone operation). Moreover, the OTA can be disabled through dedicated bit / OTP

(see CR#2 Bit[17], BST_DIS_OTA in Table 23: CR#2: Control Register 2).

Homogeneous power losses distribution in multi-phases is guaranteed thanks to design

specific measures ensuring the lowest spread for key-parameters like linear amplifier gain

and offset (GLA and GLA_OFFSET), slope compensation current (ISLOPE) and voltage on

COMP pin (VCOMP).

3.8

Operation in multiphase interleaved mode

The multiphase operation mode is needed in case of high output power requirement. The

maximum output power per phase in front of LED applications is typically 35W considering a

cost effective design. This limitation is mainly given by power losses and thermal

constraints. By sharing the current between several phases, the conduction losses (which

are proportional to the square of the conducted current) are reduced and the efficiency of

the boost stage increases, in comparison to a single-phase. Another advantage of

multiphase topology is higher effective switching frequency and lower ripple currents which

significantly reduces the filtering effort on input and output side. In ideal case of 50% duty

cycle in 2-phase mode (respectively 33.3% in 3-phase or 25% in 4-phase), the input ripple

current is reduced down to zero.

The L99LD02 can be configured in 1, 2, 3 or 4 phase mode. The 1 or 2 phase mode can be

realized with one device as shown in Figure 5: 1 or 2 phase configuration with single

L99LD02 device.

Table 3. OTA gain configuration

BITs [1÷0]

BST_GM_OTA [µS]

200

400

600

800

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