MP2932 - 6-PHASE PWM CONTROLLER WITH 8-BIT ADC CODE

MP2932 Rev.1.02

www.MonolithicPower.com

12

4/30/2012

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© 2012 MPS. All Rights Reserved.























FB

R

ISEN

R

X

R

N

OUT

I

OFS

V

REF

V

OUT

V

(7)

sense resistor connected to the ISEN+ pin, and

depending on the sensing method.

Therefore, the loadline is defined as:

ISEN

R

X

R

N

FB

R

LL

R



(8)

Output Voltage Offset Programming

In Figure 5, OFS pin is used to generate no-

load offset. A resistor RREF between DAC and

equal to the desired offset voltage.

R

C

FB

DAC

VCC

OR

GND

R

REF

OFS

GND

VCC

1.6V

0.4V

DYNAMIC

ID D/A

E/A

MP2932

REF

REF

OFS

Figure 5—Offset Voltage Programming

to generate a positive offset. The voltage

across it is regulated to 1.6V. This causes a

positive offset is:

OFS

R

REF

R

1.6

OFFSET

V





(9)

to generate a negative offset. The voltage

of OFS. The negative offset is:

OFS

R

REF

R

0.4

OFFSET

V





(10)

Enable and Disable

While in shutdown mode, the PWM outputs are

held in a Hi-Z state, and the SD signal is pulled

low to assure the Intelli-phase remain off. The

following input conditions must be met to start

MP2932.

1. VCC must reach the internal power-on reset

(POR) rising threshold.

2. EN_PWR is used to coordinate the power

sequencing between VCC and another

voltage rail. The enable comparator holds

the MP2932 in shutdown until the voltage at

EN_PWR rises above 0.875V.

3. The voltage on EN_VTT must be higher than

0.875V to enable the controller. This pin is

typically connected to the output of VTT VR.

4.

10kO

910O

MP2932 INTERNAL CIRCUIT

EXTERNAL CIRCUIT

VCC

EN_PWR

ENABLE

COMPARATOR

0.875V

0.875V

EN_VTT

POR

CIRCUIT

+12V

SOFT-START

AND

FAULT LOGIC

Figure 6—Power Sequencing Using

Threshold Sensitive Enable (EN) Function

When all conditions are satisfied, MP2932

begins the soft-start and ramps the output

voltage to 1.1V first. After remaining at 1.1V for

some time, MP2932 reads the ID code at ID

input pins. If the ID code is valid, MP2932 will

regulate the output to the final ID setting. If the

ID code is OFF code, MP2932 will shutdown,

and cycling VCC, EN_PWR or EN_VTT is

needed to restart.