MAX1624-MAX1625 Просмотр технического описания (PDF) - Maxim Integrated

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MAX1624-MAX1625

High-Speed Step-Down Controllers with Synchronous Rectification for CPU Power

Maxim Integrated 

High-Speed Step-Down Controllers with

Synchronous Rectification for CPU Power

• Minimize high-current path trace lengths. Use

very short and wide traces. From C1 to N1: 0.4 in.

(10mm) max length; D1 cathode to N2: 0.2 in.

(5mm) max length; LX node (N1 source, N2 drain,

D1 cathode, inductor L1): 0.6 in. (15mm) max

length.

2) Place the MAX1624/MAX1625 and supporting

components following these rules:

• Minimize trace lengths to the current-sense

resistor. The IC must be no farther than 0.4 in.

(10mm) from the current-sense resistor. Use a

Kelvin connection.

• Minimize ground trace lengths between the

MAX1624/MAX1625 and supporting compo-

nents. Connect components for the REF, CC1,

CC2, and FREQ pin directly to AGND. Connect

AGND and PGND at the IC.

• Keep noisy nodes and components away from

sensitive analog nodes, such as the current-

sense, voltage-feedback, REF, CC1, CC2, and

FREQ pins. Placing the IC and analog compo-

nents on the opposite side of the board from the

power-switching node is desirable. Noisy nodes

include the main switching node (LX), inductor,

and gate-drive outputs.

• Place components for the FREQ, REF, CC1,

and CC2 pins as close to the IC as possible,

within 0.2 in. (5mm).

• Keep the gate-drive traces (DH, DL, and BST)

shorter than 20mm, and route them away from

CSH, CSL, REF, FB, etc.

• Filter the VCC supply input to the IC. Bypass the

IC directly from VDD to PGND using a 0.1µF

ceramic capacitor and 4.7µF electrolytic capacitor

placed within 0.2 in. (5mm) of the IC.

• Place the voltage-feedback components close to

the FB pin of the MAX1625, within 0.2 in. (5mm).

Connect the voltage-feedback trace directly to the

CPU’s power input and route it to avoid noisy

traces.

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