MP86934 – 16V INTELLI-PHASE SOLUTION IN TQFN 3X4

MP86934 Rev.1.2

www.MonolithicPower.com

12

5/26/2021

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Current Sense Output, CS

CS

is

a

bi-directional

current

source

proportional to the inductor current. The current

sensing gain is 10μA/A and a resistor is used to

program the voltage gain proportional to the

inductor current if needed.

The CS output has two states as shown in

Table 1. In Standby mode, the CS circuit is

disabled, it needs 20us to wake up to enter to

Active mode if needed.

Table.1 CS Output States

PWM 

SYNC 

CS 

PWM 

Hi 

Active 

PWM 

Hi 

Active 

PWM 

Low 

Active 

x 

Hi‐Z (or Middle)

Standby 

The CS voltage range of 0.8V to 2.0V is

required for to get accurate CS’s current output

up to +500μA/-200μA (i.e. +50A/-25A). In

general, there is a resistor, RCS, connected from

CS pin to an external voltage which is capable

to sink small current to provide enough voltage

level to meet the required operating voltage

range.

Fig.2 shows the typical circuit diagram of CS

pin connection for getting a differential voltage

source reflected to inductor current.

Eq. 1 shows the guideline for design RCS

resistance to avoid the V(CS) voltage outs of

operating range.

0.8

2.0

CS

CS

CM

VI

R

V

V







(Eq.1)

CS

L

CS

II

G



Where VCM is the reference voltage connected

to RCS.

The VCM can be from a voltage divider from

3.3V (i.e. VCC) shown in Fig.3.

Choose RCS >> (R1//R2) to minimize the VCM

voltage variation over ICS current.

VCS

SW

PWM

Intelli-Phase

PWM

IL

Vin

VIN

GND

CS

RCS

VCM

ICS

Fig.2 Typical Circuit Diagram for CS pin

connection

Fig.3 Use VCC to generate VCM voltage for

CS signal