LTM4600HVIV(RevE) 查看數據表（PDF） - Linear Technology

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LTM4600HVIV
(Rev.:RevE)

10A, 28VIN High Efficiency DC/DC µModule

Linear Technology 

LTM4600HV

applications information

in the PCB layout to minimize the trace inductance and

high frequency AC noise.

Output Capacitors

The LTM4600HV is designed for low output voltage ripple.

The bulk output capacitors COUT is chosen with low enough

effective series resistance (ESR) to meet the output voltage

ripple and transient requirements. COUT can be low ESR

tantalum capacitor, low ESR polymer capacitor or ceramic

capacitor (X5R or X7R). The typical capacitance is 200µF

if all ceramic output capacitors are used. The internally

optimized loop compensation provides sufficient stability

margin for all ceramic capacitors applications. Additional

output filtering may be required by the system designer,

if further reduction of output ripple or dynamic transient

spike is required. Refer to Table 2 for an output capaci-

tance matrix for each output voltage droop, peak to peak

deviation and recovery time during a 5A/µs transient with

a specific output capacitance.

Fault Conditions: Current Limit and Over current

Foldback

The LTM4600HV has a current mode controller, which

inherently limits the cycle-by-cycle inductor current not

only in steady state operation, but also in transient.

To further limit current in the event of an over load condition,

the LTM4600HV provides foldback current limiting. If the

output voltage falls by more than 50%, then the maximum

output current is progressively lowered to about one sixth

of its full current limit value.

VIN to VOUT Step-Down Ratios

There are restrictions in the maximum VIN to VOUT step

down ratio that can be achieved for a given input voltage.

These constraints are shown in VIN to VOUT Step-Down

Ratio in the Typical Performance Characteristics section.

Note that additional thermal derating may apply. See the

Thermal Considerations and Output Current Derating sec-

tions of this data sheet.

Soft-Start and Latchoff with the RUN/SS pin

The RUN/SS pin provides a means to shut down the

LTM4600HV as well as a timer for soft-start and over-

current latchoff. Pulling the RUN/SS pin below 0.8V puts

the LTM4600HV into a low quiescent current shutdown

(IQ ≤ 75µA). Releasing the pin allows an internal 1.2µA

current source to charge up the timing capacitor CSS.

Inside LTM4600HV, there is an internal 1000pF capacitor

from RUN/SS pin to ground. If RUN/SS pin has an external

capacitor CSS_EXT to ground, the delay before starting is

about:

tDELAY

=

1.5V

1.2µA

• (CSS _EXT

+ 1000pF)

When the voltage on RUN/SS pin reaches 1.5V, the

LTM4600HV internal switches are operating with a clamp-

ing of the maximum output inductor current limited by

the RUN/SS pin total soft-start capacitance. As the RUN/

SS pin voltage rises to 3V, the soft-start clamping of the

inductor current is released.

For more information www.linear.com/LTM4600HV

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