RT9245CPC datasheet(17/25 Pages) RICHTEK

17 / 25 page

RT9245C

DS9245C-02 March 2007

www.richtek.com

VID on the Fly

With external pull up resistors tied to VID pins, RT9245C

converters different VID codes from CPU into output

voltage. Figure 16 and Figure 17 show the waveforms of

VID on the fly function.

Load Line Setting and Thermal Compensation

VADJ = 8 x AVG(IX) x RADJ

VOUT = VDAC - VADJ

AVG(IX) is a PTC current. By properly use an NTC resistor

at ADJ. Load line can be thermally compensated.

Figure 17

Output Voltage Offset Function

To meet Intel® requirement of initial offset of load line,

RT9245C provides programmable initial offset function.

External resistor RVOSS and voltage source at VOSS pin

generate offset current

, where VVOSS is 1V typical. One quarter of IVOSS flows

through RB1 as shown in Figure 18. Error amplifier would

hold the inverting pin equal to VDAC - VADJ. Thus output

voltage is subtracted from VDAC - VADJ for a constant offset

voltage.

A positive output voltage offset is possible by connecting

RVOSS to VDD instead of to GND. Please note that when

RVOSS is connected to VDD, VVOSS is VDD

− 2V typically

and half of IVOSS flows through RFB1. VCORE is rewritten as:

VOSS

FB1

CORE

DAC

ADJ

VOSS

V= V

- V

VOSS

FB1

ADJ

DAC

CORE

Figure 19

Voltage Offset Function

1.268

1.27

1.272

1.274

1.276

1.278

1.28

1.282

1.284

100

110

ROSS (k )

Ω)

Figure 18. Offset Setting

1/4 IVOSS

RB1

VDAC-VADJ

Figure 16

CH1:(5V/Div)

CH2:(500mV/Div)

CH3:(500mV/Div)

CH4:(1V/Div)

VID on the Fly (Falling)

Time (25

μs/Div)

VCORE

PWM

VFB

VID125

VDAC = 1.500, IOUT = 5A

CH1:(5V/Div)

CH2:(500mV/Div)

CH3:(500mV/Div)

CH4:(1V/Div)

VID on the Fly (Rising)

Time (25

μs/Div)

VCORE

PWM

VFB

VID125

VDAC = 1.500, IOUT = 5A

RT9245CPC bảng dữ liệu(PDF) 17 Page - Richtek Technology Corporation

RT9245CPC bảng dữ liệu(HTML) 17 Page - Richtek Technology Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

bảng dữ liệu tải về

Link URL