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PDF LTM4634 Data sheet ( Hoja de datos )
| Número de pieza | LTM4634 | |
| Descripción | Triple Output 5A/5A/4A Step-Down DC/DC uModule Regulator | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Features
n Three Independent High Efficiency Regulator
Channels
n IOUT1,2 = 5A, IOUT3 = 4A
n Input Voltage Range: 4.75V to 28V
n Independent VIN for Each Channel
n VOUT1,2 Voltage Range: 0.8V to 5.5V
n VOUT3 Voltage Range: 0.8V to 13.5V
n ±1.5% Maximum Total DC Output Error
n Current Mode Control/Fast Transient Response
n Frequency Synchronization
n Output Overvoltage and Overcurrent Protection
n PolyPhase® Operation with Current Sharing
n General Purpose Temperature Monitors
n Soft-Start/Voltage Tracking
n Power Good Monitors
n SnPb or RoHS Compliant Finish
n 15mm × 15mm × 5.01mm BGA Package
Applications
n Telecom, Networking and Industrial Equipment
n High Density Point of Load Voltage Regulation
LTM4634
Triple Output 5A/5A/4A
Step-Down DC/DC
µModule® Regulator
Description
The LTM®4634 integrates three complete 5A/5A/4A high
efficiency switching mode DC/DC converters into one small
package. Switching controllers, power FETs, inductors, and
most support components are included. Operating over an
input voltage range of 4.75V to 28V, the LTM4634 provides
three independent output voltages. VOUT1 and VOUT2 are
adjustable from 0.8V to 5.5V, while VOUT3 is adjustable
from 0.8V to 13.5V. Each output voltage is set by a single
external resistor.
High switching frequency and a current mode architecture
enable a very fast transient response to line and load
changes without sacrificing stability. The device supports
frequency synchronization, multiphase parallel opera-
tion, soft-start and output voltage tracking for supply rail
sequencing.
Fault protection features include overvoltage protection,
overcurrent protection and temperature monitoring. The
power module is offered in a space saving, thermally
enhanced 15mm × 15mm × 5.01mm BGA package. The
LTM4634 is available with SnPb (BGA) or RoHS compliant
terminal finish.
L, LT, LTC, LTM, µModule, PolyPhase, Burst Mode, Linear Technology and the Linear logo
are registered trademarks and PowerPath, LTpowerCAD and UltraFast are trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 5481178, 5705919, 5929620, 6100678, 6144194,
6177787, 6304066, 6580258 and 8163643. Other patents pending.
Typical Application
24V Input to 3.3V, 5V and 12V Output Regulator
24VIN
40k
5V
2Ω VIN1 VIN2 VIN3 EXTVCC INTVCC FREQ/PLLLPF
CNTL_PWR
PGOOD12
10k 10k
4.7µF
6.3V
RUN1
1µF RUN2
RUN3
TK/SS1
TK/SS2
TK/SS3
LTM4634
PGOOD3
VOUT1
VFB1
19.1k
VOUT2
VFB2
11.5k
3.3V
5V
MODE/PLLIN GND SGND
VOUT3
VFB3
4.32k
12V
4634 TA01a
For more information www.linear.com/LTM4634
24V Input Efficiency
100
95
90
85
80
75
70 VEXTVCC = 5V
24V to 3.3V EFF (750kHz) CH1
65 24V to 5V EFF (750kHz) CH2
24V to 12V EFF (750kHz) CH3
60
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
LOAD CURRENT (A)
4634 TA01b
4634f
1
1 page  
Typical Performance Characteristics
LTM4634
5V Input Efficiency (Ch1 and Ch2)
100
95
90
85
80
75
70
65
60
5V TO 1.0V EFF (250kHz)
5V TO 1.2V EFF (250kHz)
55 5V TO 1.5V EFF (250kHz)
50
45
5V TO 1.8V EFF (250kHz)
5V TO 2.5V EFF (250kHz)
5V TO 3.3V EFF (250kHz)
40
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
LOAD CURRENT (A)
4634 G01
5V Input Efficiency (Ch3)
100
95
90
85
80
75
70
65
60
55
50
45
40
0
5V TO 1.OV EFF (250kHz)
5V TO 1.2V EFF (250kHz)
5V TO 1.5V EFF (250kHz)
5V TO 1.8V EFF (250kHz)
5V TO 2.5V EFF (250kHz)
5V TO 3.3V EFF (250kHz)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
LOAD CURRENT (A)
4634 G02
12V Input Efficiency (Ch1 and Ch2)
100
95
90
85
80
75
70
65
60
55
50
45
40
0
VEXTVCC = 5V
12V TO 1.0V EFF (250kHz)
12V TO 1.2V EFF (250kHz)
12V TO 1.5V EFF (250kHz)
12V TO 1.8V EFF (250kHz)
12V TO 2.5V EFF (250kHz)
12V TO 3.3V EFF (250kHz)
12V TO 5.0V EFF (250kHz)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
LOAD CURRENT (A)
4634 G03
12V Input Efficiency (Ch3)
100
95
90
85
80
75
70 VEXTVCC = 5V
65 12V TO 1.0V EFF (250kHz)
60
12V TO 1.2V EFF (250kHz)
12V TO 1.5V EFF (250kHz)
55 12V TO 1.8V EFF (250kHz)
50 12V TO 2.5V EFF (250kHz)
45
12V TO 3.3V EFF (250kHz)
12V TO 5.0V EFF (250kHz)
40
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
LOAD CURRENT (A)
4634 G04
24V Input Efficiency (Ch1 and Ch2)
100
95
90
85
80
75
70 VEXTVCC = 5V
65 24V TO 1.0V EFF (250kHz)
60
24V TO 1.2V EFF (250kHz)
24V TO 1.5V EFF (300kHz)
55 24V TO 1.8V EFF (350kHz)
50
45
24V TO 2.5V EFF (350kHz)
24V TO 3.3V EFF (600kHz)
24V TO 5.0V EFF (750kHz)
40
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
LOAD CURRENT (A)
4634 G05
24V Input Efficiency (Ch3)
100
95
90
85
80
75
70
65
60
55
50
45
40
0
VEXTVCC = 5V
24 TO 1.0V EFF (250kHz)
24 TO 1.2V EFF (250kHz)
24 TO 1.5V EFF (250kHz)
24 TO 1.8V EFF (300kHz)
24 TO 2.5V EFF (300kHz)
24 TO 3.3V EFF (350kHz)
24 TO 5.0V EFF (500kHz)
24 TO 12V EFF (750kHz)
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
LOAD CURRENT (A)
4634 G06
24V Input Continuous, Pulse-
Skipping and Burst Mode Operation
100
95
90
85
80
75
70
65
60
55
50
45
5.0VOUT (750kHz) BURST
5.0VOUT (750kHz) PULSE
5.0VOUT (750kHz) CONT
40
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
LOAD CURRENT (A)
24V to 3.3V Load Step Response
OUTPUT
100mV/DIV
LOAD
STEP
1A/DIV
100µs/DIV
4634 G08
0A TO 2.5A, 2.5A/µs LOAD STEP
COUT = 2 × 100µF CERAMIC CAPACITOR
4634 G07
24V to 5V Load Step Response
OUTPUT
100mV/DIV
LOAD
STEP
1A/DIV
100µs/DIV
4634 G09
0A TO 2.5A, 2.5A/µs LOAD STEP
COUT = 2 × 100µF CERAMIC CAPACITOR
For more information www.linear.com/LTM4634
4634f
5
5 Page 
LTM4634
Applications Information
The typical LTM4634 application circuit is shown in Fig-
ure 22. External component selection is primarily deter-
mined by the maximum load current and output voltage.
Refer to Table 4 for specific external capacitor requirements
for particular applications.
VIN to VOUT Step-Down Ratios
There are restrictions in the VIN to VOUT step-down ratio
that can be achieved for a given input voltage. The VIN to
VOUT minimum dropout is a function of load current and
at very low input voltage and high duty cycle applications
output power may be limited as the internal top power
MOSFET is not rated for 5A operation at higher ambient
temperatures. At very low duty cycles the minimum 100ns
on-time must be maintained. See the Frequency Adjust-
ment section and temperature derating curves.
Output Voltage Programming
The PWM controller has an internal 0.8V ±1% reference
voltage. As shown in the Block Diagram, a 60.4k preci-
sion internal feedback resistor connects the VOUT and VFB
pins together.
The output voltage will default to 0.8V with no feedback
resistor. Adding a resistor RFB from VFB to ground pro-
grams the output voltage:
VOUT
=
0.8V
•
60.4k +RFB
RFB
or
RFB
=
48.32k
VOUT – 0.8
Table 1. VFB Resistor Table vs Various Output Voltages
VOUT(V) 0.8 1.0 1.2 1.5 1.8 2.5 3.3 5.0
RFB (kΩ) Open 243 121 69.8 48.7 28.7 19.1 11.5
12.0
4.32
In the parallel operation the following pins should be tied
together, VFB1 and VFB2 pins, COMP1 and COMP2 pins,
TK/SS1 and TK/SS2, and RUN1 and RUN2.
For parallel operation of VOUT1 and VOUT2, connect VFB1
and VFB2 together with a single resistor to ground whose
value is determined by:
60.4k
RFB
=
2
VOUT
0.8
–1
Input Capacitors
The LTM4634 module should be connected to a low AC
impedance DC source. Additional input capacitors are
needed for the RMS input ripple current rating. The ICIN(RMS)
equation which follows can be used to calculate the input
capacitor requirement for each channel. Typically 4.7µF
to 10µF X7R ceramics are a good choice with RMS ripple
current ratings of ~2A each. A 47µF to 100µF surface mount
aluminum electrolytic capacitor can be used for more input
bulk capacitance. This bulk input capacitor is only needed
if the input source impedance is compromised by long
inductive leads, traces or not enough source capacitance.
If low impedance power planes are used, then this bulk
capacitor is not needed.
For a buck converter, the switching duty cycle can be
estimated as:
D=
VOUT
VIN
Without considering the inductor ripple current, for each
output, the RMS current of the input capacitor can be
estimated as:
ICIN(RMS)
=
IOUT(MAX )
η%
•
D • (1– D)
(1)
In the previous equation, η% is the estimated efficiency
of the power module in decimal form (0.nn) for a given
VOUT-to-VIN ratio.
The selection of CIN is simplified by the 3-phase architec-
ture and its impact on the worst-case RMS current draw
occurs when only one channel is operating. This is true
when the three channels are powered from a common
VIN. The channel with the highest duty cycle D peaking at
0.5 and maximum load current needs to be used in the
above formula. This will give the maximum RMS capacitor
current requirement. Increasing the output current drawn
from the other channels will actually decrease the input
RMS ripple current from its maximum value. The out-of-
phase technique typically reduces the input capacitor’s
RMS ripple current by a factor of 50% when compared to
a single phase power supply solution. If the three channels
are powered from independent input sources, then each
4634f
For more information www.linear.com/LTM4634
11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet LTM4634.PDF ] | |
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