LTM4613 查看數據表（PDF） - Linear Technology
零件编号
产品描述 (功能)
生产厂家
LTM4613 Datasheet PDF : 30 Pages
| |||
LTM4613
OPERATION
Power Module Description
The LTM4613 is a standalone nonisolated switch mode
DC/DC power supply. It can deliver 8A of DC output cur-
rent with minimal external input and output capacitors.
This module provides a precisely regulated output voltage
programmable via one external resistor from 3.3VDC to
15VDC over a wide 5V to 36V input voltage. The typical
application schematic is shown in Figure 18.
The LTM4613 has an integrated constant on-time current
mode regulator, ultralow RDS(ON) FETs with fast switching
speed and integrated Schottky diodes. The typical switching
frequency is 600kHz at full load at 12V output. With current
mode control and internal feedback loop compensation,
the LTM4613 module has sufficient stability margins and
good transient performance under a wide range of operat-
ing conditions and with a wide range of output capacitors,
even all ceramic output capacitors.
Current mode control provides cycle-by-cycle fast current
limiting. Moreover, foldback current limiting is provided in
an overcurrent condition when VFB drops. Internal over-
voltage and undervoltage comparators pull the open-drain
PGOOD output low if the output feedback voltage exits a
±10% window around the regulation point. Furthermore,
in an overvoltage condition, internal top FET M1 is turned
off and bottom FET M2 is turned on and held on until the
overvoltage condition clears.
Input filter and noise cancellation circuitry reduce the
noise coupling to inputs and outputs, and ensure the
electromagnetic interference (EMI) meets the limits of
EN55022 Class B (see Figure 7).
Pulling the RUN pin below 1V forces the controller into
its shutdown state, turning off both M1 and M2. At light
load currents, discontinuous mode (DCM) operation can
be enabled to achieve higher efficiency compared to con-
tinuous mode (CCM) by setting FCB pin higher than 0.6V.
When the DRVCC pin is connected to INTVCC, an integrated
5V linear regulator powers the internal gate drivers. If a
5V external bias supply is applied on DRVCC pin, then an
efficiency improvement will occur due to the reduced power
loss in the internal linear regulator. This is especially true
at the higher input voltage range.
The MPGM, MARG0, and MARG1 pins are used to sup-
port voltage margining, where the percentage of margin
is programmed by the MPGM pin, while the MARG0 and
MARG1 select positive or negative margining. The PLLIN
pin provides frequency synchronization of the device to
an external clock. The TRACK/SS pin is used for power
supply tracking and soft-start programming.
APPLICATIONS INFORMATION
The typical LTM4613 application circuit is shown in Fig-
ure 18. External component selection is primarily deter-
mined by the input voltage, the maximum load current and
the output voltage. Refer to Table 2 for specific external
capacitor requirements for a particular application.
VIN to VOUT Step-Down Ratios
There are restrictions in the maximum VIN and VOUT step
down ratio that can be achieved for a given input voltage.
These constraints are shown in the Typical Performance
Characteristic curve labeled “VIN to VOUT Step-Down
Ratio.” Note that additional thermal derating may be ap-
plied. See the Thermal Considerations and Output Current
Derating section in this data sheet.
Output Voltage Programming and Margining
The PWM controller has an internal 0.6V reference volt-
age. As shown in the Block Diagram, a 100k 0.5% internal
feedback resistor connects the VOUT and VFB pins together.
Adding a resistor, RFB, from the VFB pin to the SGND pin
programs the output voltage.
VOUT
=
0.6V
•
100k +RFB
RFB
or equivalently,
RFB =
100k
VOUT
0.6V
−
1
4613fd
10
For more information www.linear.com/LTM4613
Share Link: 