MAX17021 datasheet(14/48 Pages) MAXIM

14 / 48 page

Dual-Phase, Quick-PWM Controllers for

IMVP-6+/IMVP-6.5 CPU Core Power Supplies

______________________________________________________________________________________

Pin Description

NAME

FUNCTION

PGDIN

System Power-Good Logic Input. PGDIN indicates the power status of other system rails and is used for

power-supply sequencing. After power-up to the boot voltage, the output voltage remains at VBOOT,

CLKEN

remains high, and PWRGD remains low as long as the PGDIN stays low. When PGDIN is pulled high, the

output transitions to selected VID voltage, and

CLKEN is pulled low. If the system pulls PGDIN low during

normal operation, the MAX17021/MAX17082/MAX17482 immediately drive

CLKEN high, pull PWRGD low,

and slew the output to the boot voltage (using two-phase pulse-skipping mode). The controller remains at

the boot voltage until PGDIN goes high again,

SHDN is toggled, or the VCC input power supply is cycled.

THRM

Input of Internal Comparator. Connect the output of a resistor- and thermistor-divider (between VCC and

GND) to THRM. Select the components such that the voltage at THRM falls below 1.5V (30% of VCC) at

the desired high temperature.

IMON

(MAX17082/

MAX17482

only)

Current-Monitor Output. The MAX17082/MAX17482 IMON output source a current that is directly

proportional to the current-sense voltage as defined by:

IIMON = Gm(IMON) x (VCSP_ - VCSN_)

where Gm(IMON) = 2.4mS (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.

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

the following equation:

RIMON = 0.999V/(IMAX x RSENSE x Gm(IMON))

where IMAX is defined in the Current Monitor section of the Intel IMVP-6.5 specification and based on

discrete increments (20A, 30A, 40A, etc.), RSENSE is the typical effective value of the current-sense

element (sense resistor or inductor DCR) that is used to provide the current-sense voltage, and

Gm(IMON) is the typical transconductance amplifier gain as defined in the Electrical Characteristics

table.

The IMON voltage is internally clamped to a maximum of 1.1V (typ).

The transconductance amplifier and voltage clamp are internally compensated, so IMON cannot directly

drive large capacitance values. To filter the IMON signal, use an RC filter as shown in Figure 2.

IMON is pulled to ground when MAX17082/MAX17482 are in shutdown.

Typical Operating Characteristics (continued)

(Circuit of Figure 1. VIN = 12V, VCC = VDD = 5V, SHDN = VCC, D0–D6 set for 1.075V, TA = +25°C, unless otherwise specified.)

MAX17021 toc23

100

μs/div

A. VOUT, 500mV/div

B. DL_, 5V/div

C. PWRGD, 5V/div

0.875V

OUTPUT OVERVOLTAGE WAVEFORM

MAX17021 toc24

μs/div

A. 5V BIAS SUPPLY, 5V/div

B. VOUT, 500mV/div

C. PWRGD, 5V/div

D. DL_, 5V/div

E. ILX1, 10A/div

IOUT = 10A

0.875V

10A

BIAS SUPPLY REMOVAL

(UVLO RESPONSE)

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