LT3790_15 Datasheet, PDF(23/28 Page) Linear Technology – 60V Synchronous 4-Switch Buck-Boost Controller

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LT3790_15 Datasheet, PDF (23/28 Pages) Linear Technology – 60V Synchronous 4-Switch Buck-Boost Controller

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LT3790

Applications Information

n Connect the input capacitors, CIN, and output capacitors,

COUT, closely to the power MOSFETs. These capaci-

tors carry the MOSFET AC current in boost and buck

operation.

n Route SNSN and SNSP leads together with minimum

PC trace spacing. Avoid sense lines pass through noisy

areas, such as switch nodes. Ensure accurate current

sensing with Kelvin connections at the SENSE resistor.

n Connect the VC pin compensation network close to the

IC, between VC and the signal ground pins. The capaci-

tor helps to filter the effects of PCB noise and output

voltage ripple voltage from the compensation loop.

n Connect the INTVCC bypass capacitor, CVCC, close to the

IC, between the INTVCC and the power ground pins. This

capacitor carries the MOSFET driversâ current peaks. An

additional 0.1ÂµF ceramic capacitor placed immediately

next to the INTVCC and PGND pins can help improve

noise performance substantially.

Differences Between LT3790 and LT3791-1

The LT3790 is an improved version of the LT3791-1 and

is recommended for use in new designs. Some external

component values may change, but otherwise, the LT3790

is functionally equivalent to the LT3791-1. The differences

between the two products are:

1. The LT3790 has a 60mV (typical) full-scale V(ISP-ISN)

current sense voltage, compared to 100mV (typical) for

the LT3791-1. This change allows lower power current

sense resistors to be used for most applications.

2. The LT3790 CTRL pin linear range is from 0V to 1.1V,

and has a turn-off threshold of 50mV(typical), compared

to a 200mV to 1.1V linear range and 175mV (typical)

turn-off threshold for the LT3791-1. These changes

make it easier to parallel two or more LT3790 ICs for

higher power levels.

3. The LT3790 C/10 pin pulls low when the V(ISP-ISN) voltage

is less than 1/10 full scale, compared to the LT3791-1,

where C/10 pulls low when both V(ISP-ISN) is less than

1/10 full scale and VFB is greater than 1.15V(typical).

Since the C/10 pin is used to allow DCM mode for some

applications, this change ensures that negative current

does not occur at light loads for a broader range of

applications.

For more information www.linear.com/LT3790

3790f

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