MAX8770GTL+T Maxim Integrated Products, MAX8770GTL+T Datasheet - Page 43

• Manufacturer Part Number: MAX8770GTL+T
• Description: IC CTLR PS 2/1PH QUICK PWM 40QFN
• Manufacturer: Maxim Integrated Products

Specifications of MAX8770GTL+T

• Applications: Controller, Intel IMVP-6
• Voltage - Input: 4 ~ 26 V
• Number Of Outputs: 1
• Voltage - Output: 0.125 ~ 1.5 V
• Operating Temperature: -40°C ~ 105°C
• Mounting Type: *
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

PWM Controller for IMVP-6+ CPU Core Power Supplies
CONFIDENTIAL INFORMATION – RESTRICTED TO INTEL
Figure 11. PC Board Layout Example
stability in the current-balance loop. For most applica-
tions, a 470pF capacitor from CCI to the switching reg-
ulator’s output works well.
Connecting the compensation network to the output
(V
voltage signal, especially during transients. To reduce
noise pickup in applications that have a widely distrib-
uted layout, it is sometimes helpful to connect the com-
pensation network to the quiet analog ground rather
than V
Voltage positioning dynamically lowers the output volt-
age in response to the load current, reducing the out-
put capacitance and processor’s power-dissipation
requirements. The controller uses a transconductance
amplifier to set the transient and DC output voltage
droop (Figure 2) as a function of the load. This adjusta-
bility allows flexibility in the selected current-sense
resistor value or inductor DCR, and allows smaller cur-
OUT
) allows the controller to feed-forward the output-
OUT
MAX8770/MAX8771/MAX8772 Dual-Phase, Quick-
.
Voltage Positioning and Loop
______________________________________________________________________________________
PLACE CONTROLLER ON BACKSIDE WHEN POSSIBLE, USING THE
GROUND PLANE TO SHIELD THE IC FROM EMI.
SEE THE EVALUATION KIT FOR ANALOG/POWER GROUND AND
CONTROLLER LAYOUT EXAMPLE.
Compensation
INDUCTOR
INDUCTOR
C
C
C
C
OUT
OUT
OUT
OUT
OUTPUT
INPUT
CPU
rent-sense resistance to be used, reducing the overall
power dissipated.
Connect a resistor (R
the DC steady-state droop (load line) based on the
required voltage-positioning slope (R
where the effective current-sense resistance (R
depends on the current-sense method (see the Current
Sense section), and the voltage-positioning amplifier’s
transconductance (G
defined in the Electrical Characteristics table. The con-
troller sums together the input signals of the current-
sense inputs (CSP_, CSN_).
When the inductors’ DCR is used as the current-sense
element (R
should include an NTC thermistor to minimize the tem-
perature dependence of the voltage-positioning slope.
INDUCTOR
INDUCTOR
C
C
C
C
OUT
OUT
OUT
OUT
SENSE
R
FB
= R
Steady-State Voltage Positioning
®
=
FB
DCR
m(FB)
IMVP-6 LICENSEES
) between FB and V
R
SENSE m FB
), each current-sense input
R
DROOP
) is typically 600µS, as
G
(
DROOP
)
):
OUT
SENSE
to set
43
)