LM5171 datasheet(21/89 Pages) TI2

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Table 6-1. CFG Programming for IMONs and I2C Address (continued)

CFG Resistor Selection (kΩ) (1% Resistor)

I2C Address

IMON Function

Min

Max

1.10

1.13

0x23

IMON_IL

1.65

1.69

0x24

IMON_IL

2.43

2.49

0x25

IMON_IL

3.32

3.40

0x26

IMON_IL

4.53

4.64

0x27

IMON_IL

6.65

6.81

0x27

IMON_BSTOUT

10.2

10.5

0x26

IMON_BSTOUT

13.7

14.0

0x25

IMON_BSTOUT

18.7

19.1

0x24

IMON_BSTOUT

26.1

26.7

0x23

IMON_BSTOUT

37.4

38.3

0x22

IMON_BSTOUT

60.4

61.9

0x21

IMON_BSTOUT

95.3

97.6

0x20

IMON_BSTOUT

6.3.4 High Voltage Inputs (HV1, HV2)

Figure 6-4 shows the external and internal configuration for the HV1 and HV2 pins. Both pins are rated at 85VDC.

For independent channel operation connect the HV1 and HV2 pins to the HV-port voltage rails for each channel,

respectively, which are not necessarily the same HV-port. When operating in parallel dual phase configuration to

support high power the two HV pins can be tied together and connect to the same HV-port. As shown in Figure

6-4 to bypass high frequency noises apply a small RC filter like 10Ω and 0.1µF at these two pins.

AGND

HV-Port2

To CH-1

Controller

HV1

HV-Port1

HV2

To CH-2

Controller

Cfilter

Rfilter

Independent Operation

Cfilter

Rfilter

Figure 6-4. HV1 and HV2 Pins Configuration

6.3.5 Current Sense Amplifier

Each channel of the LM5171-Q1 has a bidirectional high accuracy high-speed current sense amplifier. The

current sense polarity is determined by the DIR1 and DIR2. The amplifier gain is 40, such that a smaller current

sense resistor is supported to reduce power dissipation. The amplified current sense signal is used to perform

the following functions:

• Applied to the inverting input of the trans-conductance amplifier for the current loop regulation.

• Used to reconstruct the channel current monitor signal at the IMON1 and IMON2 pins.

• Monitored by the cycle-by-cycle peak current limit comparator for the instantaneous overcurrent protection.

• Sensed by the current zero cross detector to operate the synchronous rectifiers in the diode emulation mode.

Select the current sense resistor RCS for 50mV current sense voltage at rated current. Connect the CSA1,

CSB1, CSA2 and CSB2 pins via Kelvin connection for accurate sensing.

It is very important that the current sense resistors are low-inductive. Otherwise the sensed current signals are

distorted even if the parasitic inductance is only a few nH. Such inductance has only minimal influence on the

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LM5171-Q1

SNVSC75B – APRIL 2023 – REVISED SEPTEMBER 2025

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