Data Sheet

LT8277

analog.com

Rev 0

18 of 31

A table of manufacturers appears in Table 7.

Table 7. Recommended Capacitors Vendors

NAME

WEBSITE

Panasonic

industrial.panasonic.com/ww

Wurth Elektronik

www.we-online.com

Murata

www.murata.com

Taiyo Yuden

www .yuden.co.jp

Current Sense Structure Selection

Two methods of inductor current sense are available with the LT8277. Note that for both methods, each phase

needs its own current sense structure and inductor. The current sense structure programs the inductor current

limit. This, in turn, determines the output current limit. If the inductor choice matches the guidelines above, then

Equation 5 describes the output current limit. Note that the total output current limit increases with the number of

participating phases, n.

������������������������(������������������������������������) = 0.85 · ������������,������������������

������������������������

������������������������

(5)

The first current sense method uses a resistor connected in series with the inductor on the VIN side. The SNSP and

SNSN pins monitor the voltage at this resistor. The inductor current limit using this method is shown in Figure 31.

Keep the power dissipation capability of the resistor in mind for high-current applications.

Figure 31. Input Current Limit Programmed by Sense Resistor

������������,������������������ =

75������������

������������

������

(6)

For some high-current applications, a series-sense resistor may dissipate an unacceptable amount of power. In that

case, a parallel RC network can be used to reconstruct the voltage dropped across the inductor’s equivalent series

resistance (ESR). The components used for this method will not dissipate significant amounts of power, but the

accuracy of the inductor current limit can suffer since the tolerance of more components gets introduced to the

relationship.

VIN

Lx

RS

SNSPx

SNSNx

LT8277