MAX17409 Просмотр технического описания (PDF) - Maxim Integrated

Номер в каталоге

Компоненты Описание

производитель

MAX17409

1-Phase Quick-PWM GPU Controller

Maxim Integrated 

1-Phase Quick-PWM GPU Controller

Pin Description

PIN

NAME

FUNCTION

Current Monitor Output. The MAX17409 IMON output sources a current that is directly proportional

to the current-sense voltage as defined by:

IIMON = Gm(IMON) x (VCSP - VCSN)

where Gm(IMON) = 5mS (typ).

The IMON current is unidirectional (sources current out of IMON only) for positive current-sense

values. For negative current-sense voltages, the IMON current is zero.

1

IMON Connect an external resistor between IMON and GNDS to create the desired IMON gain based on

the following equation:

RIMON = 1.0V/(ILOAD(MAX) x RSENSE x Gm(IMON))

where ILOAD(MAX) is the maximum load current, and RSENSE is the current-sense voltage.

The IMON voltage is internally clamped to 1.1V. The transconductance amplifier and voltage

clamp are internally compensated, so IMON cannot drive large external capacitance values. To

filter the IMON signal, use an RC filter as shown in Figure 1.

Remote Ground-Sense Input/Positive Offset Input. Connect directly to the ground-sense pin or

2

GNDS/OFSP

ground connection of the load. GNDS internally connects to a transconductance amplifier that

adjusts the feedback voltage—compensating for voltage drops between the regulator’s ground and

the processor’s ground.

Remote-Sense Feedback Input and Voltage-Positioning Transconductance Amplifier Output.

Connect resistor RFB between FB and the output remote-sense pin (or Kelvin-sensed to the supply

pin of the load) for best accuracy and to set the steady-state droop based on the voltage-

positioning gain requirement:

RFB = RDROOP/(RSENSE x GMD)

3

FB

where RDROOP_DC is the desired voltage-positioning slope, GMD = 600µS (typ), and RSENSE is the

current-sense resistance with respect to CSP to CSN current-sense inputs. See the Current Sense

section for details on designing with sense resistors or inductor DCR sensing.

Shorting FB directly to the output effectively disables voltage positioning, but impacts the stability

requirements. Designs that disable voltage positioning require a higher minimum output

capacitance ESR to maintain stability (see the Output Capacitor Selection section).

FB enters a high-impedance state in shutdown.

Negative Inductor Current-Sense Input. Connect CSN to the negative terminal of the inductor

4

CSN

current-sensing resistor or directly to the negative terminal of the inductor if the lossless DCR

sensing method is used (see Figure 3).

Positive Inductor Current-Sense Input. Connect CSP to the positive terminal of the inductor current-

5

CSP

sensing resistor or directly to the positive terminal of the filtering capacitor used when the

lossless DCR sensing method is used (see Figure 3).

Pulse-Skipping Control Input. The SKIP signal indicates the power usage and sets the operating

mode of the MAX17409. When the system forces SKIP high, the MAX17409 immediately enters

automatic pulse-skipping mode. The controller returns to continuous forced-PWM mode when SKIP

is pulled low and the output is in regulation. SKIP determines the operating mode and output-

voltage transition slew rate as shown in the truth table below:

6

SKIP

SKIP

Functionality

0

Normal slew rate, forced-PWM mode

1

Normal slew rate, skip mode

The SKIP state is ignored during soft-start and shutdown. The MAX17409 always uses pulse-

skipping mode during startup to ensure a monotonic power-up. During shutdown, the controller

always uses forced-PWM mode so the output can be actively discharged.

10 ______________________________________________________________________________________

Share Link: