LINER LTM4616V

LTM4616
Dual 8A per Channel Low
VIN DC/DC µModule
DESCRIPTION
FEATURES
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
Complete Dual DC/DC Regulator System
Input Voltage Range: 2.7V to 5.5V
Dual 8A Outputs, or Single 16A Output with a 0.6V
to 5V Range
Output Voltage Tracking and Margining
±1.75% Total DC Output Error (–40°C to 125°C)
Current Mode Control/Fast Transient Response
Power-Good Tracking and Margining
Overcurrent/Thermal Shutdown Protection
Onboard Frequency Synchronization
Spread Spectrum Frequency Modulation
Multiphase Operation
Selectable Burst Mode® Operation
Output Overvoltage Protection
Gold-Pad Finish Allows Soldering with Pb and PbFree Solder Paste
Small Surface Mount Footprint, Low Profile
(15mm × 15mm × 2.82mm) LGA Package
APPLICATIONS
■
■
■
Telecom, Networking and Industrial Equipment
Storage and ATCA, PCI Express Cards
Battery Operated Equipment
L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.
μModule is a trademark of Linear Technology Corporation. All other trademarks are the property
of their respective owners. Protected by U.S. Patents, including 5481178, 6580258, 6304066,
6127815, 6498466, 6611131, 6724174.
The LTM®4616 is a complete dual 2-phase 8A per channel
switch mode DC/DC power regulator system in a 15mm ×
15mm surface mount LGA package. Included in the package
are the switching controller, power FETs, inductor and all
support components. Operating from an input voltage
range of 2.7V to 5.5V, the LTM4616 supports two outputs
within a voltage range of 0.6V to 5V, each set by a single
external resistor. This high efficiency design delivers up
to 8A continuous current (10A peak) for each output. Only
bulk input and output capacitors are needed, depending
on ripple requirement. The part can also be configured for
a 2-phase single output at up to 16A.
The low profile package (2.82mm) enables utilization
of unused space on the back side of PC boards for high
density point-of-load regulation.
Fault protection features include overvoltage protection,
overcurrent protection and thermal shutdown. The power
module is offered in a space saving and thermally enhanced
15mm × 15mm × 2.82mm LGA package. The LTM4616 is
Pb-free and RoHS compliant.
Different Combinations of Input and Output
Number of Inputs
Number of Outputs
IOUT (MAX)
2
2
8A, 8A
2
1
16A
1
2
8A, 8A
1
1
16A
TYPICAL APPLICATION
Efficiency vs Load Current
95
Dual Output DC/DC μModule™ Regulator
VIN1
VOUT1
3.3V/8A
VOUT1
FB1
10μF
LTM4616
2.21k
100μF
ITHM1
VIN2 3.3V TO 5V
VIN2
VOUT2
2.5V/8A
VOUT2
90
EFFICIENCY (%)
VIN1 5V
5VIN 3.3VOUT
5VIN 2.5VOUT
85
80
FB2
10μF
3.09k
100μF
75
ITHM2
GND1
70
GND2
4616 TA01a
0
2
4
6
LOAD CURRENT (A)
8
4616 TA01b
4616fa
1
LTM4616
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
VIN1, SVIN1, VIN2, SVIN2................................ –0.3V to 6V
CLKOUT1, CLKOUT2 .................................... –0.3V to 2V
PGOOD1, PLLLPF1, CLKIN1, PHMODE1,
MODE1, PGOOD2, PLLLPF2, CLKIN2,
PHMODE2, MODE2................................. –0.3V to VIN
ITH1, ITHM1, RUN1, FB1, TRACK1, MGN1,
BSEL1, ITH2 , ITHM2 , RUN2, FB2, TRACK2,
MGN2, BSEL2 ......................................... –0.3V to VIN
VOUT1, VOUT2 , SW1, SW2............................ –0.3V to VIN
Internal Operating Temperature Range
(Note 2) .............................................–40°C to 125°C
Junction Temperature ........................................... 125°C
Storage Temperature Range...................–55°C to 125°C
TOP VIEW
VIN2
VOUT2
SGND2 & CONTROL
M
L
K
J
GND2
H
SW2,
I/O & CONTROL
G
F
SGND1 & CONTROL
VIN1
VOUT1
E
D
C
GND1
B
A
1
2
3
4
5
6
7
8
9
10
11
12
SW1, I/O & CONTROL
LGA PACKAGE
144-LEAD (15mm × 15mm × 2.8mm)
TJMAX = 125°C, θJP = 2°C/W, θJC = 16°C/W
ORDER INFORMATION
LEAD FREE FINISH
TRAY
PART MARKING*
PACKAGE DESCRIPTION
INTERNAL TEMPERATURE RANGE
LTM4616EV#PBF
LTM4616EV#PBF
LTM4616V
144-Lead (15mm × 15mm × 2.82mm) LGA
–40°C to 125°C
LTM4616IV#PBF
LTM4616IV#PBF
LTM4616V
144-Lead (15mm × 15mm × 2.82mm) LGA
–40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
This product is only offered in trays. For more information go to: http://www.linear.com/packaging/
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the –40°C to 125°C
internal operating temperature range. TA = 25°C, VIN = 5V unless otherwise noted. Per the typical application in Figure 18. Specified
as each channel (Note 3).
SYMBOL
PARAMETER
VIN1(DC), VIN2(DC)
Input DC Voltage
VOUT1(DC), VOUT2(DC) Output Voltage, Total Variation
with Line and Load
CONDITIONS
MIN
●
CIN = 10μF × 1, COUT = 100μF Ceramic,
100μF POSCAP, RFB = 6.65k
VIN = 2.7V to 5.5V,
IOUT = IOUT(DC)MIN to IOUT(DC)MAX (Note 4)
●
TYP
2.7
MAX
UNITS
5.5
V
1.472
1.49
1.508
V
1.464
1.49
1.516
V
2.05
1.85
2.2
2.0
2.35
2.15
V
V
Input Specifications
VIN1(UVLO),
VIN2(UVLO)
Undervoltage Lockout Threshold
SVIN Rising
SVIN Falling
4616fa
2
LTM4616
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the –40°C to 125°C
internal operating temperature range. TA = 25°C, VIN = 5V unless otherwise noted. Per the typical application in Figure 18. Specified
as each channel (Note 3).
SYMBOL
PARAMETER
CONDITIONS
MIN
IQ(VIN1, VIN2)
Input Supply Bias Current
VIN = 3.3V, VOUT = 1.5V, No Switching, Mode = VIN
VIN = 3.3V, VOUT = 1.5V, No Switching, Mode = 0V
VIN = 3.3V, VOUT = 1.5V, Switching Continuous
400
1.15
55
μA
mA
mA
VIN = 5V, VOUT = 1.5V, No Switching, Mode = VIN
VIN = 5V, VOUT = 1.5V, No Switching, Mode = 0V
VIN = 5V, VOUT = 1.5V, Switching Continuous
450
1.3
75
μA
mA
mA
1
μA
4.5
2.93
A
A
Shutdown, RUN = 0, VIN = 5V
IS(VIN1, VIN2)
Input Supply Current
VIN = 3.3V, VOUT = 1.5V, IOUT = 8A
VIN = 5V, VOUT = 1.5V, IOUT = 8A
TYP
MAX
UNITS
Output Specifications
IOUT1(DC), IOUT2(DC)
Output Continuous Current Range VOUT = 1.5V
(Note 4)
VIN = 3.3V, 5.5V
VIN = 2.7V
0
0
8
5
A
A
ΔVOUT1(LINE)/VOUT1
ΔVOUT2(LINE)/VOUT2
Line Regulation Accuracy
VOUT = 1.5V, VIN from 2.7V to 5.5V, IOUT = 0A
●
0.1
0.25
%/V
ΔVOUT1(LOAD)/VOUT1
ΔVOUT2(LOAD)/VOUT2
Load Regulation Accuracy
VOUT = 1.5V (Note 4)
VIN = 3.3V, 5.5V, ILOAD = 0A to 8A
VIN = 2.7V, ILOAD = 0A to 5A
●
●
0.3
0.3
0.5
0.5
%
%
VOUT1(AC), VOUT2(AC) Output Ripple Voltage
IOUT = 0A, COUT = 100μF X5R Ceramic, VIN = 5V,
VOUT = 1.5V
fS1, fS2
Switching Frequency
IOUT = 8A, VIN = 5V, VOUT = 1.5V
fSYNC1, fSYNC2
SYNC Capture Range
ΔVOUT1(START),
ΔVOUT2(START)
Turn-On Overshoot
tSTART1, tSTART2
Turn-On Time
10
1.25
1.5
0.75
mVP-P
1.75
MHz
2.25
MHz
COUT = 100μF, VOUT = 1.5V, IOUT = 0A
VIN = 3.3V
VIN = 5V
10
10
mV
mV
COUT = 100μF, VOUT = 1.5V, VIN = 5V,
IOUT = 1A Resistive Load, Track = VIN
100
μs
ΔVOUT1(LS),
ΔVOUT2(LS)
Peak Deviation for Dynamic Load Load: 0% to 50% to 0% of Full Load,
COUT = 100μF Ceramic x2, 470μF POSCAP,
VIN = 5V, VOUT = 1.5V
20
mV
tSETTLE1, tSETTLE2
Settling Time for Dynamic Load
Step
Load: 0% to 50% to 0% of Full Load, VIN = 5V,
VOUT = 1.5V, COUT = 100μF
10
μs
IOUT1(PK), IOUT2(PK)
Output Current Limit
COUT = 100μF
VIN = 2.7V, VOUT = 1.5V
VIN = 3.3V, VOUT = 1.5V
VIN = 5V, VOUT = 1.5V
8
11
13
A
A
A
Control Section
FB1, FB2
SS Delay
Voltage at FB Pin
IOUT = 0A, VOUT = 1.5V, VIN = 2.7V to 5.5V
●
0.590
0.587
Internal Soft-Start Delay
IFB
VRUN1, VRUN2
RUN Pin On/Off Threshold
RUN Rising
RUN Falling
TRACK1, TRACK2
Tracking Threshold (Rising)
Tracking Threshold (Falling)
Tracking Disable Threshold
RUN = VIN
RUN = 0V
1.4
1.3
0.596
0.596
0.602
0.606
V
V
90
μs
0.2
μA
1.55
1.4
0.57
0.18
VIN – 0.5
1.7
1.5
V
V
V
V
V
4616fa
3
LTM4616
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the –40°C to 125°C
internal operating temperature range. TA = 25°C, VIN = 5V unless otherwise noted. Per the typical application in Figure 18. Specified
as each channel (Note 3).
SYMBOL
PARAMETER
CONDITIONS
RFBHI1, RFBHI2
Resistor Between VOUT and FB
Pins
MIN
TYP
MAX
UNITS
9.95
10
10.05
kΩ
ΔVPGOOD1, ΔVPGOOD2 PGOOD Range
%Margining
±10
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTM4616E is guaranteed to meet performance specifications
over the 0°C to 125°C internal operating temperature range. Specifications
over the full –40°C to 125°C internal operating temperature range are
assured by design, characterization and correlation with statistical process
Specified as Each Channel
Efficiency vs Load Current
100
CONTINUOUS MODE
Efficiency vs Load Current
100
CONTINUOUS MODE
95
95
90
90
90
85
80
5VIN 1.2VOUT
5VIN 1.5VOUT
5VIN 1.8VOUT
5VIN 2.5VOUT
5VIN 3.3VOUT
75
70
0
2
4
LOAD CURRENT
EFFICIENCY (%)
95
EFFICIENCY (%)
EFFICIENCY (%)
100
85
80
3.3VIN 1.2VOUT
3.3VIN 1.5VOUT
3.3VIN 1.8VOUT
3.3VIN 2.5VOUT
75
8
4616 G01
0
2
4
LOAD CURRENT
CONTINUOUS MODE
85
80
2.7VIN 1.0VOUT
2.7VIN 1.5VOUT
2.7VIN 1.8VOUT
75
70
70
6
%
%
%
%
%
%
6
11
16
–6
–11
–16
controls. The LTM4616I is guaranteed to meet specifications over the full
internal operating temperature range. Note that the maximum ambient
temperature is determined by specific operating conditions in conjunction
with board layout, the rated package thermal resistance and other
environmental factors.
Note 3: Two channels are tested separately and the same testing
conditions are applied to each channel.
Note 4: See Output Current Derating curves for different VIN, VOUT and TA.
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency vs Load Current
5
10
15
–5
–10
–15
4
9
14
–4
–9
–14
MGN = VIN , BSEL = 0V
MGN = VIN , BSEL = VIN
MGN = VIN , BSEL = Float
MGN = 0V, BSEL = 0V
MGN = 0V, BSEL = VIN
MGN = 0V, BSEL = Float
Output Voltage Margining
Percentage
%
6
8
4616 G02
0
1
4
3
2
5
LOAD CURRENT (A)
6
7
4616 G03
4616fa
4
LTM4616
TYPICAL PERFORMANCE CHARACTERISTICS
Burst Mode Efficiency with
5V Input
VIN to VOUT Step-Down Ratio
4.0
IOUT = 8A
VOUT = 1.2V
VOUT = 1.5V
VOUT = 1.8V
VOUT = 2.5V
VOUT = 3.3V
3.5
90
2.5
VOUT (V)
EFFICIENCY (%)
3.0
80
70
60
VOUT = 1.5V
VOUT = 2.5V
VOUT = 3.3V
40
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1
LOAD CURRENT (A)
VIN to VOUT Step-Down Ratio
4.0
3.0
2.5
2.0
2.0
1.5
1.5
1.0
1.0
0.5
0.5
0
0
1
2
3
VIN (V)
IOUT = 5A
VOUT = 1.2V
VOUT = 1.5V
VOUT = 1.8V
VOUT = 2.5V
VOUT = 3.3V
3.5
VOUT (V)
100
50
Specified as Each Channel
4
4616 G04
0
5
6
0
1
2
3
VIN (V)
4
5
4616 G06
4616 G05
Supply Current vs VIN
6
Load Transient Response
Load Transient Response
1.6
SUPPLY CURRENT (mA)
1.4
1.2
VO = 1.2V PULSE-SKIPPING MODE
1
0.8
0.6
ILOAD
1A/DIV
ILOAD
1A/DIV
VOUT
50mV/DIV
VOUT
50mV/DIV
VO = 1.2V BURST MODE
0.4
0.2
0
2.5
3
3.5
4
4.5
INPUT VOLTAGE (V)
5
4616 G08
VIN = 5V
20μs/DIV
VOUT = 3.3V
2A/μs STEP
COUT = 2 × 100μF X5R, 470μF 4V POSCAP
4616 G09
VIN = 5V
20μs/DIV
VOUT = 2.5V
2A/μs STEP
COUT = 2 × 100μF X5R, 470μF 4V POSCAP
Load Transient Response
Load Transient Response
5.5
4616 G07
Load Transient Response
ILOAD
1A/DIV
ILOAD
1A/DIV
ILOAD
1A/DIV
VOUT
50mV/DIV
VOUT
50mV/DIV
VOUT
50mV/DIV
4616 G10
VIN = 5V
20μs/DIV
VOUT = 1.8V
2.5A/μs STEP
COUT = 2 × 100μF X5R, 470μF 4V POSCAP
4616 G11
VIN = 5V
20μs/DIV
VOUT = 1.5V
2.5A/μs STEP
COUT = 2 × 100μF X5R, 470μF 4V POSCAP
VIN = 5V
20μs/DIV
VOUT = 1.2V
2.5A/μs STEP
COUT = 2 × 100μF X5R, 470μF POSCAP
4616 G12
4616fa
5
LTM4616
TYPICAL PERFORMANCE CHARACTERISTICS
Start-Up
Specified as Each Channel
VFB vs Temperature
Load Regulation vs Current
0
602
–0.1
600
VOUT
0.5V/DIV
VFB (mV)
598
VIN
2V/DIV
LOAD REGULATION (%)
VIN = 5.5V
VIN = 3.3V
596
VIN = 2.7V
594
VIN = 5V
50μs/DIV
VOUT = 1.5V
COUT = 100μF NO LOAD AND 8A LOAD
(DEFAULT 100μs SOFT-START)
–0.2
–0.3
–0.4
4616 G13
FC MODE
VIN = 3.3V
VOUT = 1.5V
–0.5
592
590
–50
–25
0
50
75
25
TEMPERATURE (°C)
100
125
–0.6
0
2
4616 G14
4
6
LOAD CURRENT (A)
8
4616 G15
Short-Circuit Protection
(2.5V Short, No Load)
2.5V Output Current
Short-Circuit Protection
(2.5V Short, 4A Load)
3.0
2V/DIV
2.5
VIN
5V/DIV
VIN
OUTPUT VOLTAGE (V)
5V/DIV
2V/DIV
2.0
VOUT
VOUT
IOUT LOAD
5A/DIV
5A/DIV
1.5
IOUT
IOUT SHORT
5A/DIV
1.0
VIN = 5V
VOUT = 2.5V
0.5
50μs/DIV
4616 G17
VIN = 5V
VOUT = 2.5V
50μs/DIV
4616 G18
0
0
5
10
15
OUTPUT CURRENT (A)
20
4616 G16
PIN FUNCTIONS
VIN1, VIN2, (BANK1 and BANK2); (F1-F4, E1-E4, C1-C2,
D1-D2) and (J1-J2, K1-K2, L1-L4, M1-M4): Power Input
Pins. Apply input voltage between these pins and GND
pins. Recommend placing input decoupling capacitance
directly between VIN pins and GND pins.
VOUT1, VOUT2 (BANK3 and BANK6); (D9-D12, E9-E12,
F9-F12) and (K9-K12, L9-L12, M9-M12): Power Output
Pins. Apply output load between these pins and GND
pins. Recommend placing output decoupling capacitance
directly between these pins and GND pins. See Table 1.
GND1 and GND2 (BANK2 and BANK5); (A1-A5, A12, B1B5, B7-B12, C3-C12, D3-D7) and (G1-G5, G12, H1-H5,
H7-H12, J3-J12, K3-K7): Power Ground Pins for Both
Input and Output Returns.
SVIN1 and SVIN2 (E5 and L5): Signal Input Voltage for Each
Channel. This pin is internally connected to VIN through
a lowpass filter.
SGND1 and SGND2 (F5 and M5): Signal Ground Pin for
Each Channel. Return ground path for all analog and low
power circuitry. Tie a single connection to the output
capacitor GND in the application. See layout guidelines
in Figure 17.
4616fa
6
LTM4616
PIN FUNCTIONS
MODE1 and MODE2 (A8 and G8): Mode Select Input for
Each Channel. Tying this pin high enables Burst Mode
operation. Tying this pin low enables forced continuous
operation. Floating this pin or tying it to VIN/2 enables
pulse-skipping operation.
CLKIN1 and CLKIN2 (A7 and G7): External Synchronization
Input to Phase Detector for Each Channel. This pin is
internally terminated to SGND with a 50k resistor. The
phase-locked loop will force the internal top power PMOS
turn on to be synchronized with the rising edge of the
CLKIN signal. Connect this pin to SVIN to enable spread
spectrum modulation. During external synchronization,
make sure the PLLLPF pin is not tied to VIN or GND.
PLLLPF1 and PLLLPF2 (E6 and L6): Phase-Locked Loop
Lowpass Filter for Each Channel. An internal lowpass filter
is tied to this pin. In spread spectrum mode, placing a
capacitor here to SGND controls the slew rate from one
frequency to the next. Alternatively, floating this pin allows
normal running frequency at 1.5MHz, tying this pin to SVIN
forces the part to run at 1.33 times its normal frequency
(2MHz), tying it to ground forces the frequency to run at
0.67 times its normal frequency (1MHz).
PHMODE1 and PHMODE2 (A9 and G9): Phase Selector
Input for Each Channel. This pin determines the phase
relationship between the internal oscillator and CLKOUT. Tie
it high for 2-phase operation, tie it low for 3-phase operation,
and float or tie it to VIN/2 for 4-phase operation.
MGN1 and MGN2 (A10 and G10): Voltage Margining Pin
for Each Channel. Tie this pin to VOUT to disable margining.
For margining, connect a voltage divider from VIN to GND
with the center point connected to the MGN pin for the
specific channel. Each resistor should be close to 50k.
Margin High is within 0.3V of VIN , and Margin Low is
within 0.3V of GND. See the Applications section and
Figure 18 for margining control. The specified tri-state
drivers are capable of the high and low requirements for
margining.
BSEL1 and BSEL2 (A6 and G6): Margining Bit Select Pin
for Each Channel. Tying BSEL low selects ±5% margin
value, tying it high selects 10% margin value. Floating it
or tying it to VIN/2 selects 15% margin value.
TRACK1 and TRACK2 (E8 and L8): Output Voltage Tracking
Pin for Each Channel. Voltage tracking is enabled when
the TRACK voltage is below 0.57V. If tracking is not
desired, then connect the TRACK pin to SVIN. If TRACK
is not tied to SVIN , then the TRACK pin’s voltage needs to
be below 0.18V before the chip shuts down even though
RUN is already low. Do not float this pin. A resistor and
capacitor can be applied to the TRACK pin to increase the
soft-start time of the regulator. TRACK1 and TRACK2 can
be tied together for parallel operation and tracking. See
the Applications section.
FB1 and FB2 (D8 and K8): The Negative Input of the Error
Amplifier for Each Channel. Internally, this pin is connected
to VOUT with a 10k precision resistor. Different output
voltages can be programmed with an additional resistor
between FB and GND pins. In PolyPhase® operation, tying
the FB pins together allows for parallel operation. See
Applications section for details.
ITH1 and ITH2 (F8 and M8): Current Control Threshold and
Error Amplifier Compensation Point for Each Channel. The
current comparator threshold increases with this control
voltage. Tie together in parallel operation.
ITHM1 and ITHM2 (E7 and L7): Negative Input to the Internal
ITH Differential Amplifier for Each Channel. Tie this pin to
SGND for single phase operation on each channel. For
PolyPhase operation, tie the master’s ITHM to SGND while
connecting all of the ITHM pins together at the master.
PGOOD1 and PGOOD2 (A11 and G11): Output Voltage
Power Good Indicator for Each Channel. Open-drain logic
output that is pulled to ground when the output voltage
is not within ±10% of the regulation point. Power good
is disabled during margining.
RUN1 and RUN2 (F6 and M6): Run Control Pin. A voltage
above 1.5V will turn on the module.
SW1 and SW2 (B6 and H6): Switching Node of Each
Channel That is Used for Testing Purposes. This can be
connected to copper on the board for improved thermal
performance.
CLKOUT1 and CLKOUT2 (F7 and M7): Output Clock
Signal for PolyPhase Operation. The phase of CLKOUT is
determined by the state of the PHMODE pin.
PolyPhase is a registered trademark of Linear Technology Corporation.
4616fa
7
LTM4616
SIMPLIFIED BLOCK DIAGRAM
VIN2
VOUT2
SGND2 & CONTROL
M
L
K
J
GND2
H
SW2,
I/O & CONTROL
G
F
SGND1 & CONTROL
VIN1
VOUT1
E
D
C
GND1
B
A
1
2
3
4
5
6
7
8
9
10
11
SW1, I/O & CONTROL
12
4616 F01
TOP VIEW OF LGA PINOUT
LOOKING THROUGH COMPONENT
SVIN1
INTERNAL
FILTER
TRACK1
VOUT1
10μF
10μF
10μF
VIN1
3V TO 5.5V
+
CIN1
PGND1
MGN1
BSEL1
M1
SW1
PGOOD1
MODE1
L
POWER
CONTROL
RUN1
VOUT1
1.5V
8A
CLKIN1
+
CLKOUT1
10μF
M2
COUT1
PHMODE1
PGND1
ITH1
50k
INTERNAL
COMP
10k
PLLLPF1
ITHM1
PGND1
SGND1
SVIN2
INTERNAL
FILTER
TRACK2
VOUT2
FB1
RSET1
6.65k
INTERNAL
FILTER
10μF
10μF
10μF
VIN2
3V TO 5.5V
+
CIN2
PGND2
MGN2
BSEL2
M3
SW2
PGOOD2
MODE2
L
POWER
CONTROL
RUN2
VOUT2
1.2V
8A
CLKIN2
+
CLKOUT2
M4
10μF
COUT2
PHMODE2
PGND2
ITH2
50k
INTERNAL
COMP
10k
PLLLPF2
ITHM2
PGND2
FB2
RSET2
10k
INTERNAL
FILTER
SGND2
4616 BD
Figure 1. Simplified LTM4616 Block Diagram
4616fa
8
LTM4616
SIMPLIFIED BLOCK DIAGRAM
Table 1. Decoupling Requirements. TA = 25°C, Block Diagram Configuration.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
CIN1
CIN2
External Input Capacitor Requirement
(VIN1 = 2.7V to 5.5V, VOUT1 = 1.5V)
(VIN2 = 2.7V to 5.5V, VOUT2 = 2.5V)
IOUT1 = 8A
IOUT2 = 8A
22
22
μF
μF
COUT1
COUT2
External Output Capacitor Requirement
(VIN1 = 2.7V to 5.5V, VOUT1 = 1.5V)
(VIN2 = 2.7V to 5.5V, VOUT2 = 2.5V)
IOUT1 = 8A
IOUT2 = 8A
100
100
μF
μF
OPERATION
The LTM4616 is a dual-output standalone nonisolated
switching mode DC/DC power supply. It can provide two
8A outputs with few external input and output capacitors.
This module provides precisely regulated output voltages
programmable via external resistors from 0.6VDC to 5VDC
over 2.7V to 5.5V input voltages. The typical application
schematic is shown in Figure 18.
The LTM4616 has integrated constant frequency current
mode regulators and built-in power MOSFET devices with
fast switching speed. The typical switching frequency is
1.5MHz. For switching noise sensitive applications, it can
be externally synchronized from 0.75MHz to 2.25MHz.
Even spread spectrum switching can be implemented in
the design to reduce noise.
With current mode control and internal feedback loop
compensation, the LTM4616 module has sufficient stability margins and good transient performance with a wide
range of output capacitors, even with all ceramic output
capacitors.
Current mode control provides cycle-by-cycle fast current
limit and thermal shutdown in an overcurrent condition.
Internal overvoltage and undervoltage comparators pull
the open-drain PGOOD output low if the output feedback
voltage exits a ±10% window around the regulation point.
The power good pins are disabled during margining.
Pulling the RUN pins below 1.3V forces the regulators
into a shutdown state, by turning off both MOSFETs. The
TRACK pin is used for programming the output voltage
ramp and voltage tracking during start-up. See Applications Information section.
The LTM4616 is internally compensated to be stable over
all operating conditions. Table 3 provides a guideline for
input and output capacitances for several operating conditions. The Linear Technology μModule Power Design Tool
will be provided for transient and stability analysis. The
FB pin is used to program the output voltage with a single
external resistor to ground.
Multiphase operation can be easily employed with the
synchronization and phase mode controls. Up to 12 phases
can be cascaded to run simultaneously with respect to each
other by programming the PHMODE pin to different levels.
The LTM4616 has clock in and clock out for poly phasing
multiple devices or frequency synchronization.
High efficiency at light loads can be accomplished with
selectable Burst Mode operation using the MODE pin. These
light load features will accommodate battery operation.
Efficiency graphs are provided for light load operation in
the Typical Performance Characteristics section.
Output voltage margining is supported, and can be programed from ±5% to ±15% using the MGN and BSEL
pins.
4616fa
9
LTM4616
APPLICATIONS INFORMATION
The typical LTM4616 application circuit is shown in
Figure 18. External component selection is primarily
determined by the maximum load current and output
voltage. Refer to Table 3 for specific external capacitor
requirements for a particular application.
VIN to VOUT Step-Down Ratios
There are restrictions in the maximum VIN to VOUT stepdown ratio that can be achieved for a given input voltage.
Each output of the LTM4616 is 100% duty cycle, but the
VIN to VOUT minimum drop out is still shown as a function
of its load current. For 5V input, all outputs can deliver 8A.
For 3.3V input, all outputs can deliver 8A, except 2.5VOUT
which is limited to 6A. All outputs derived from 2.7V input
are limited to 5A.
For a buck converter, the switching duty-cycle can be
estimated as:
D=
VOUT
VIN
Without considering the inductor current ripple, the RMS
current of the input capacitor can be estimated as:
ICIN(RMS) =
Output Voltage Programming
The PWM controller has an internal 0.596V reference
voltage. As shown in the Block Diagram, a 10k 0.5%
internal feedback resistor connects VOUT and FB pins
together. The output voltage will default to 0.596V with
no feedback resistor. Adding a resistor RFB from FB pin
to GND programs the output voltage:
VOUT = 0.596V •
step is required up to the 4A level. A 47μF to 100μF
surface mount aluminum electrolytic bulk 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 47μF capacitor is not needed.
10k + RFB
RFB
IOUT(MAX)
η%
• D • (1– D)
In the above equation, η% is the estimated efficiency of the
power module so the RMS input current at the worst case
for 8A maximum current is about 4A. The bulk capacitor
can be a switcher-rated electrolytic aluminum capacitor,
polymer capacitor for bulk input capacitance. Each internal
10μF ceramic input capacitor is typically rated for 2 amps
of RMS ripple current.
Output Capacitors
Table 2. FB Resistor vs Various Output Voltages
VOUT
0.596V
1.2V
1.5V
1.8V
2.5V
3.3V
RFB
Open
10k
6.65k
4.87k
3.09k
2.21k
For parallel operation of N the below equation can be
used to solve for RFB . Tying the FB pins together for each
parallel output:
RFB =
10k / N
VOUT
−1
0.596
Input Capacitors
The LTM4616 module should be connected to a low AC
impedance DC source. For each regulator, three 10μF
ceramic capacitors are included inside the module.
Additional input capacitors are only needed if a large load
The LTM4616 is designed for low output voltage ripple
noise. The bulk output capacitors defined as COUT are
chosen with low enough effective series resistance (ESR) to
meet the output voltage ripple and transient requirements.
COUT can be a low ESR tantalum capacitor, low ESR
polymer capacitor or ceramic capacitor. The typical output
capacitance range is from 47μF to 220μF. Additional output
filtering may be required by the system designer, if further
reduction of output ripples or dynamic transient spikes is
required. Table 3 shows a matrix of different output voltages
and output capacitors to minimize the voltage droop and
overshoot during a 3A/μs transient. The table optimizes
total equivalent ESR and total bulk capacitance to optimize
the transient performance. Stability criteria are considered
in the Table 3 matrix, and the Linear Technology μModule
Power Design Tool will be provided for stability analysis.
4616fa
10
LTM4616
APPLICATIONS INFORMATION
Table 3. Output Voltage Response Versus Component Matrix (Refer to Figure 18) 0A to 3A Load Step
TYPICAL MEASURED VALUES
COUT1 VENDORS
VALUE
TDK
22μF, 6.3V
Murata
22μF, 16V
TDK
100μF, 6.3V
Murata
100μF, 6.3V
VOUT
(V)
1.0
1.0
1.0
1.0
1.2
1.2
1.2
1.2
1.5
1.5
1.5
1.5
1.5
1.5
1.8
1.8
CIN
(CERAMIC)
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
CIN
(BULK)*
100μF
100μF
100μF
100μF
100μF
100μF
100μF
100μF
100μF
100μF
100μF
100μF
100μF
100μF
100μF
100μF
PART NUMBER
C3216X7S0J226M
GRM31CR61C226KE15L
C4532X5R0J107MZ
GRM32ER60J107M
COUT1
(CERAMIC)
100μF × 2
100μF × 2
100μF × 2
22μF × 1
100μF × 2
22μF × 1
100μF × 2
22μF × 1
100μF × 2
22μF × 1
100μF × 1
22μF × 1
100μF × 2
22μF × 1
100μF × 1
22μF × 1
COUT2
(BULK)
470μF
COUT2 VENDORS
Sanyo POSCAP
CIN (BULK) VENDORS
Sanyo
VALUE
470μF, 4V
VALUE
100μF, 10V
PART NUMBER
4TPE470M
PART NUMBER
10CE100FH
ITH
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
C1
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
C3
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
VIN
(V)
5
5
2.7
2.7
5
5
2.7
2.7
5
5
3.3
3.3
2.7
2.7
5
5
DROOP
(mV)
20
30
30
25
20
20
30
30
32
25
22
25
30
25
42
25
PEAK-TO- PEAK
DEVIATION (mV)
40
60
60
50
40
41
60
60
64
50
42
50
60
50
80
50
RECOVERY
TIME (μs)
40
25
25
25
25
25
20
25
20
25
25
25
25
25
25
30
LOAD STEP
(A/μs)
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
RFB
(kΩ)
14.7
14.7
14.7
14.7
10
10
10
10
6.65
6.65
6.65
6.65
6.65
6.65
4.87
4.87
1.8
10μF
100μF
100μF × 2
None
1.8
10μF
100μF
22μF × 1
470μF
None
1.8
10μF
100μF
100μF × 2
None
1.8
10μF
100μF
22μF × 1
470μF
None
2.5
10μF
100μF
100μF × 1
None
2.5
10μF
100μF
22μF × 1
470μF
None
2.5
10μF
100μF
100μF × 1
None
2.5
10μF
100μF
22μF × 1
470μF
None
3.3
10μF
100μF
100μF × 1
None
3.3
10μF
100μF
22μF × 1
470μF
None
*Bulk capacitance is optional if VIN has very low input impedance.
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
3.3
3.3
2.7
2.7
5
5
3.3
3.3
5
5
35
25
35
35
35
32
50
32
65
40
70
50
70
20
40
65
100
65
135
87
30
30
30
30
30
40
30
40
30
40
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
4.87
4.87
4.87
4.87
3.09
3.09
3.09
3.09
2.21
2.21
470μF
470μF
470μF
470μF
470μF
470μF
470μF
Multiphase operation will reduce effective output ripple as
a function of the number of phases. Application Note 77
discusses this noise reduction versus output ripple current cancellation, but the output capacitance will be more
a function of stability and transient response. The Linear
Technology μModule Power Design Tool will calculate the
output ripple reduction as the phase number increases
by N times.
Burst Mode Operation
The LTM4616 is capable of Burst Mode operation on
each regulator in which the power MOSFETs operate
intermittently based on load demand, thus saving quiescent
current. For applications where maximizing the efficiency
at very light loads is a high priority, Burst Mode operation
should be applied. To enable Burst Mode operation, simply
tie the MODE pin to VIN. During this operation, the peak
current of the inductor is set to approximately 20% of
4616fa
11
LTM4616
APPLICATIONS INFORMATION
the maximum peak current value in normal operation
even though the voltage at the ITH pin indicates a lower
value. The voltage at the ITH pin drops when the inductor’s
average current is greater than the load requirement. As
the ITH voltage drops below 0.2V, the BURST comparator
trips, causing the internal sleep line to go high and turn
off both power MOSFETs.
In Burst Mode operation, the internal circuitry is partially
turned off, reducing the quiescent current to about 450μA
for each output. The load current is now being supplied
from the output capacitors. When the output voltage drops,
causing ITH to rise above 0.25V, the internal sleep line goes
low, and the LTM4616 resumes normal operation. The next
oscillator cycle will turn on the top power MOSFET and the
switching cycle repeats. Each regulator can be configured
for Burst Mode operation.
Pulse-Skipping Mode Operation
In applications where low output ripple and high efficiency
at intermediate currents are desired, pulse-skipping mode
should be used. Pulse-skipping operation allows the
LTM4616 to skip cycles at low output loads, thus increasing
efficiency by reducing switching loss. Floating the MODE pin
or tying it to VIN /2 enables pulse-skipping operation. This
allows discontinuous conduction mode (DCM) operation
down to near the limit defined by the chip’s minimum
on-time (about 100ns). Below this output current level,
the converter will begin to skip cycles in order to maintain
output regulation. Increasing the output load current
slightly, above the minimum required for discontinuous
conduction mode, allows constant frequency PWM. Each
regulator can be configured for Pulse-Skipping mode.
Forced Continuous Operation
In applications where fixed frequency operation is more
critical than low current efficiency, and where the lowest
output ripple is desired, forced continuous operation should
be used. Forced continuous operation can be enabled by
tying the MODE pin to GND. In this mode, inductor current
is allowed to reverse during low output loads, the ITH
voltage is in control of the current comparator threshold
throughout, and the top MOSFET always turns on with
each oscillator pulse. During start-up, forced continuous
mode is disabled and inductor current is prevented
from reversing until the LTM4616’s output voltage is in
regulation. Each regulator can be configured for Forced
Continuous mode.
Multiphase Operation
For output loads that demand more than 8A of current,
two outputs in LTM4616 or even multiple LTM4616s can
be cascaded to run out-of-phase to provide more output
current without increasing input and output voltage ripple.
The CLKIN pin allows the LTC4616 to synchronize to an
external clock (between 0.75MHz and 2.25MHz) and the
internal phase-locked loop allows the LTM4616 to lock
onto CLKIN’s phase as well. The CLKOUT signal can be
connected to the CLKIN pin of the following LTM4616 stage
to line up both the frequency and the phase of the entire
system. Tying the PHMODE pin to SVIN , SGND or SVIN /2
(floating) generates a phase difference (between CLKIN
and CLKOUT) of 180°, 120° or 90° respectively, which
corresponds to a 2-phase, 3-phase or 4-phase operation. A
total of 12 phases can be cascaded to run simultaneously
with respect to each other by programming the PHMODE
pin of each LTM4616 to different levels. For a 6-phase
example in Figure 2, the 2nd stage that is 120° out-ofphase from the 1st stage can generate a 240° (PHMODE
= 0) CLKOUT signal for the 3rd stage, which then can
generate a CLKOUT signal that’s 420°, or 60° (PHMODE
= SVIN) for the 4th stage. With the 60° CLKIN input, the
next two stages can shift 120° (PHMODE = 0) for each
to generate a 300° signal for the 6th stage. Finally, the
signal with a 60° phase shift on the 6th stage (PHMODE
is floating) goes back to the 1st stage. Figure 3 shows the
configuration for 12-phase operation.
A multiphase power supply significantly reduces the
amount of ripple current in both the input and output
capacitors. The RMS input ripple current is reduced by,
and the effective ripple frequency is multiplied by, the
number of phases used (assuming that the input voltage
is greater than the number of phases used times the output
voltage). The output ripple amplitude is also reduced by
the number of phases used.
The LTM4616 device is an inherently current mode controlled device, so parallel modules will have very good
4616fa
12
LTM4616
APPLICATIONS INFORMATION
0
120
CLKIN CLKOUT
+120
PHMODE
CLKIN CLKOUT
PHMODE
PHASE 1
(420)
60
240
+120
SVIN
+180
CLKIN CLKOUT
CLKIN CLKOUT
PHMODE
PHMODE
PHASE 5
PHASE 3
180
+120
300
CLKIN CLKOUT
+120
PHMODE
PHMODE
PHASE 4
PHASE 2
CLKIN CLKOUT
4616 F02
PHASE 6
Figure 2. 6-Phase Operation
0
CLKIN CLKOUT
90
+90
PHMODE
CLKIN CLKOUT
180
+90
PHMODE
CLKIN CLKOUT
+90
PHMODE
CLKIN CLKOUT
PHASE 4
PHASE 7
PHASE 10
120
210
300
(420)
60
CLKIN CLKOUT
PHMODE
CLKIN CLKOUT
PHMODE
PHASE 5
PHASE 8
+90
+120
PHMODE
PHASE 1
+90
(390)
30
270
CLKIN CLKOUT
+120
PHMODE
CLKIN CLKOUT
+90
PHMODE
PHASE 2
150
+90
PHMODE
PHASE 11
CLKIN CLKOUT
PHASE 3
CLKIN CLKOUT
+90
PHMODE
PHASE 6
4616 F03
240
CLKIN CLKOUT
PHMODE
PHASE 9
330
+90
CLKIN CLKOUT
PHMODE
PHASE 12
Figure 3. 12-Phase Operation
current sharing. This will balance the thermals on the
design. Tie the ITH pins of each LTM4616 together to share
the current evenly. To reduce ground potential noise, tie
the ITHM pins of all LTM4616s together and then connect
to the SGND of the master at the point it connects to the
output capacitor GND. See layout guideline in Figure 17.
Figure 19 shows a schematic of the parallel design. The
FB pins of the parallel module are tied together.
Input RMS Ripple Current Cancellation
Application Note 77 provides a detailed explanation of
multiphase operation. The input RMS ripple current cancellation mathematical derivations are presented, and a
graph is displayed representing the RMS ripple current
reduction as a function of the number of interleaved phases.
Figure 4 shows this graph.
Spread Spectrum Operation
Switching regulators can be particularly troublesome where
electromagnetic interference (EMI) is concerned.
Switching regulators operate on a cycle-by-cycle basis to
transfer power to an output. In most cases, the frequency
of operation is fixed based on the output load. This method
of conversion creates large components of noise at the
frequency of operation (fundamental) and multiples of the
operating frequency (harmonics).
To reduce this noise, the LTM4616 can run in spread
spectrum operation by tying the CLKIN pin to SVIN .
In spread spectrum operation, the LTM4616’s internal
oscillator is designed to produce a clock pulse whose
period is random on a cycle-by-cycle basis but fixed
4616fa
13
LTM4616
APPLICATIONS INFORMATION
0.60
1-PHASE
2-PHASE
3-PHASE
4-PHASE
6-PHASE
0.55
0.50
RMS INPUT RIPPLE CURRENT
DC LOAD CURRENT
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
0.1 0.15
0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9
DUTY FACTOR (VO/VIN)
4616 F04
Figure 4. Normalized Input RMS Ripple Current vs Duty Factor for One to Six Channels (Phases)
between 70% and 130% of the nominal frequency. This
has the benefit of spreading the switching noise over
a range of frequencies, thus significantly reducing the
peak noise. Spread spectrum operation is disabled if
CLKIN is tied to ground or if it’s driven by an external
frequency synchronization signal. A capacitor value
of 0.01μF to 0.1μF be placed from the PLLLPF pin to
ground to control the slew rate of the spread spectrum
frequency change.
VTRACK is the track ramp applied to the slave’s track pin.
VTRACK has a control range of 0V to 0.596V, or the internal
reference voltage. When the master’s output is divided
down with the same resistor values used to set the slave’s
output, then the slave will coincident track with the master
until it reaches its final value. The master will continue to
its final value from the slave’s regulation point. Voltage
tracking is disabled when VTRACK is more than 0.596V. RTA in
Figure 5 will be equal to RFB for coincident tracking.
Output Voltage Tracking
The track pin of the master can be controlled by an external
ramp or by RSR and CSR in Figure 5 referenced to VIN . The
RC ramp time can be programmed using equation:
Output voltage tracking can be programmed externally
using the TRACK pin. The output can be tracked up and
down with another regulator. The master regulator’s output
is divided down with an external resistor divider that is the
same as the slave regulator’s feedback divider to implement
coincident tracking. The LTM4616 uses an accurate 10k
resistor internally for the top feedback resistor. Figure 5
shows an example of coincident tracking:
10k Slave = 1+
• VTRACK
R TA 0.596V t = – ln 1–
•
C
•
R
VIN SR SR
Ratiometric tracking can be achieved by a few simple
calculations and the slew rate value applied to the master’s
track pin. As mentioned above, the TRACK pin has a control
range from 0V to 0.596V. The master’s TRACK pin slew
4616fa
14
LTM4616
APPLICATIONS INFORMATION
rate is directly equal to the master’s output slew rate in
Volts/Time:
MR
• 10k = R TB
SR
where MR is the master’s output slew rate and SR is the
slave’s output slew rate in Volts/Time. When coincident
tracking is desired, then MR and SR are equal, thus RTB
is equal to 10k. RTA is derived from equation:
For example: MR = 3.3V/ms and SR = 1.5V/ms. Then
RTB = 22.1k. Solve for RTA to equal to 4.87k.
0.596V
VFB VFB VTRACK
+
–
10k RFB
R TB
MASTER OUTPUT
OUTPUT VOLTAGE (V)
R TA =
In ratiometric tracking, a different slew rate maybe desired
for the slave regulator. RTB can be solved for when SR is
slower than MR. Make sure that the slave supply slew rate
is chosen to be fast enough so that the slave output voltage
will reach it final value before the master output.
where VFB is the feedback voltage reference of the regulator
and VTRACK is 0.596V. Since RTB is equal to the 10k top
feedback resistor of the slave regulator in equal slew rate
or coincident tracking, then RTA is equal to RTB with VFB
= VTRACK . Therefore RTB = 10k and RTA = 6.65k in Figure
5. Figure 6 shows the output voltage for coincident
tracking.
SLAVE OUTPUT
TIME
4616 F06
Figure 6. Output Voltage Coincident Tracking
CLKIN1
VIN 4V TO 5.5V
VIN1
RUN
10μF
RSR
SW1
CLKIN1
CLKOUT1 CLKIN2
CLKOUT2
SVIN1
FB1
RUN1
ITH1
BSEL1
TRACK1
MASTER
3.3V
RTB
10k
RTA
6.65k
MGN1
LTM4616
SLAVE
1.5V/8A
VOUT2
VIN2
10μF
100μF
PGOOD1
PHMODE1
RUN
RFB1
2.21k
ITHM1
PLLLPF1
MODE1
CSR
MASTER
3.3V/7A
VOUT1
SVIN2
FB2
RUN2
ITH2
ITHM2
PLLLPF2
PGOOD2
MODE2
PHMODE2
BSEL2
TRACK2
MGN2
SW2
RFB2
6.65k
SGND1
GND1
SGND2
100μF
100μF
PGOOD
BSEL
GND2
4616 F05
FOR TRACK1:
1. TIE TO VIN TO DISABLE TRACK WITH DEFAULT 100μs SOFT START
2. APPLY A CONTROL RAMP WITH RSR AND CSR TIED TO VIN WITH t = –(ln(1–0.596/VIN) • RSR • CSR))
3. APPLY AN EXTERNAL TRACKING RAMP DIRECTLY
Figure 5. Dual Outputs (3.3V and 1.5V) with Tracking
4616fa
15
LTM4616
APPLICATIONS INFORMATION
For applications that do not require tracking or sequencing,
simply tie the TRACK pin to SVIN to let RUN control the
turn on/off. Connecting TRACK to SVIN also enables the
~100μs of internal soft-start during start-up.
Power Good
The PGOOD pin is an open-drain pin that can be used to
monitor valid output voltage regulation. This pin monitors
a ±10% window around the regulation point. As shown
in Figure 20, the sequencing function can be realized in a
dual output application by controlling the RUN pins and the
PGOOD signals from each other. The 1.5V output begins
its soft starting after the PGOOD signal of 3.3V output
becomes high, and 3.3V output starts its shutdown after
the PGOOD signal of 1.5V output becomes low. This can
be applied to systems that require voltage sequencing
between the core and sub-power supplies.
Stability Compensation
The module has already been internally compensated
for all output voltages. Table 2 is provided for most application requirements. The Linear Technology μModule
Power Design Tool will be provided for other control loop
optimization.
Output Margining
Thermal Considerations and Output Current Derating
The power loss curves in Figures 7 and 8 can be used
in coordination with the load current derating curves in
Figures 9 to16 for calculating an approximate θJA thermal
resistance for the LTM4616 with various heatsinking and
airflow conditions. Both LTM4616 outputs are placed in
parallel for a total output current of 16A, and the power
loss curves are plotted for specific output voltages up to
16A. The derating curves are plotted with each output at 8A
combined for a total of 16A. The output voltages are 1.2V,
2.5V and 3.3V. These are chosen to include the lower and
higher output voltage ranges for correlating the thermal
resistance. Thermal models are derived from several
temperature measurements in a controlled temperature
chamber along with thermal modeling analysis. The
junction temperatures are monitored while ambient
temperature increased with and without airflow. The
junctions are maintained at ~115°C while lowering output
8
8
7
7
6
6
POWER LOSS (W)
POWER LOSS (W)
For a convenient system stress test on the LTM4616’s
output, the user can program each output to ±5%, ±10%
or ±15% of its normal operational voltage. The MGN pin is
tied to the output voltage to disable margining. When the
MGN pin is low, it forces negative margining, in which the
output voltage is below the regulation point. When MGN is
high, the output voltage is forced to above the regulation
point. The MGN pin with a voltage divider is driven with a
small tri-state gate as shown in Figure 18 for three margin
states, (High, Low, and No Margin). The amount of output
voltage margining is determined by the BSEL pin. When
BSEL is low, it’s 5%. When BSEL is high, it’s 10%. When
BSEL is floating, it’s 15%. When margining is active, the
internal output overvoltage and undervoltage comparators
are disabled and PGOOD remains high.
5
4
3
4
3
2
2
1
0
5
3.3VIN 1.2VOUT
3.3VIN 2.5VOUT
0
4
8
12
16
1
0
5VIN 1.2VOUT
5VIN 3.3VOUT
0
4
8
12
16
LOAD CURRENT (A)
LOAD CURRENT (A)
4616 F07
Figure 7. 1.2V, 2.5V Power Loss
4616 F08
Figure 8. 1.2V, 3.3V Power Loss
4616fa
16
LTM4616
APPLICATIONS INFORMATION
16
14
16
16
14
14
400 LFM
0 LFM
10
200 LFM
8
6
400 LFM
12
10
0 LFM
8
200 LFM
6
12
10
0 LFM
8
4
4
2
2
2
25
55
70
85
40
100
AMBIENT TEMPERATURE (°C)
0
115
0
40
50
60
70
80
90 100
AMBIENT TEMPERATURE (°C)
4616 F09
110
Figure 10. 5VIN to 1.2VOUT
with No Heatsink
16
14
14
14
0 LFM
8
200 LFM
12
400 LFM
0 LFM
10
LOAD CURRENT (A)
LOAD CURRENT (A)
10
8
200 LFM
6
12
400 LFM
10
6
4
4
2
2
2
0
40
50
60
70
80
90 100
AMBIENT TEMPERATURE (°C)
110
40
60
100
AMBIENT TEMPERATURE (°C)
120
Figure 13. 3.3VIN to 1.2VOUT
with No Heatsink
current or power while increasing ambient temperature.
The 115°C is chosen to allow for a 10°C margin window
relative to the maximum 125°C. The decreased output
current will decrease the internal module loss as ambient
temperature is increased. The power loss curves in Figures 7
and 8 show this amount of power loss as a function of
load current that is specified with both channels in parallel. The monitored junction temperature of 115°C minus
the ambient operating temperature specifies how much
module temperature rise can be allowed. As an example, in
Figure 10 the load current is derated to 10A at ~ 80°C and
the power loss for the 5V to 1.2V at 10A output is ~3W.
If the 80°C ambient temperature is subtracted from the
115°C maximum junction temperature, then difference of
35°C divided by 3.2W equals a 10.9°C/W. Table 4 specifies
0
200 LFM
30
50
70
90
110
AMBIENT TEMPERATURE (°C)
4616 F13
4616 F12
Figure 12. 5VIN to 1.2VOUT
with BGA Heatsink
80
0 LFM
8
4
0
115
Figure 11. 5VIN to 3.3VOUT
with BGA Heatsink
16
400 LFM
55
70
85
40
100
AMBIENT TEMPERATURE (°C)
4616 F11
16
6
25
4616 F10
Figure 9. 5VIN to 3.3VOUT
with No Heatsink
12
200 LFM
6
4
0
LOAD CURRENT (A)
LOAD CURRENT (A)
12
LOAD CURRENT (A)
LOAD CURRENT (A)
400 LFM
4616 F14
Figure 14. 3.3VIN to 2.5VOUT
with No Heatsink
a 10.5°C/W value which is very close. Table 4 and Table 5
provide equivalent thermal resistances for 1.2V and 3.3V
outputs, with and without airflow and heatsinking. The
printed circuit board is a 1.6mm thick four layer board
with two ounce copper for the two outer layers and one
ounce copper for the two inner layers. The PCB dimensions
are 95mm × 76mm. The BGA heatsinks are listed below
Table 5. At load currents on each channel from 3A to 8A
(6A to16A in parallel on the derate curves); the thermal
resistance values in Tables 4 and 5 are closely accurate.
As the load currents go below the 3A level on each channel
the thermal resistance starts to increase due to the reduced
power loss on the board. The approximate thermal
resistance values for these lower currents is 15°C/W.
4616fa
17
LTM4616
16
16
14
14
12
LOAD CURRENT (A)
LOAD CURRENT (A)
APPLICATIONS INFORMATION
400 LFM
10
0 LFM
8
6
200 LFM
4
400 LFM
10
0 LFM
8
200 LFM
6
4
2
0
12
2
40
50
60
70
80
0
90
100 110 120
AMBIENT TEMPERATURE (°C)
30
50
70
90
110
AMBIENT TEMPERATURE (°C)
4616 F15
4616 F16
Figure 15. 3.3VIN 1.2VOUT with BGA Heatsink
Figure 16. 3.3VIN 2.5VOUT with BGA Heatsink
Table 4. 1.2V Output
DERATING CURVE
VIN (V)
POWER LOSS CURVE
AIR FLOW (LFM)
HEAT SINK
θJA (°C/W)
Figures 10, 13
3.3, 5
Figures 7, 8
0
None
10.5
Figures 10, 13
3.3, 5
Figures 7, 8
200
None
8.0
Figures 10, 13
3.3, 5
Figures 7, 8
400
None
7.0
Figures 12, 15
3.3, 5
Figures 7, 8
0
BGA Heat Sink
9.5
Figures 12, 15
3.3, 5
Figures 7, 8
200
BGA Heat Sink
6.3
Figures 12, 15
3.3, 5
Figures 7, 8
400
BGA Heat Sink
5.2
DERATING CURVE
VIN (V)
POWER LOSS CURVE
AIR FLOW (LFM)
HEAT SINK
θJA (°C/W)
Figure 9
5
Figure 8
0
None
10.5
Figure 9
5
Figure 8
200
None
8.0
Figure 9
5
Figure 8
400
None
7.0
Figure 11
5
Figure 8
0
BGA Heat Sink
9.8
Figure 11
5
Figure 8
200
BGA Heat Sink
7.0
Figure 11
5
Figure 8
400
BGA Heat Sink
5.5
Table 5. 3.3V Output
Heatsink Manufacturer
Wakefield Engineering
Part No: LTN20069
Phone Number: 603-635-2800
AAVID Thermalloy
Part No: 375424B000346
Phone Number: 603-224-9988
Safety Considerations
Layout Checklist/Example
The LTM4616 modules do not provide isolation from VIN
to VOUT. There is no internal fuse. If required, a slow blow
fuse with a rating twice the maximum input current needs
to be provided to protect each unit from catastrophic
failure. The device does support thermal shutdown and
overcurrent protection.
The high integration of LTM4616 makes the PCB board
layout very simple and easy. However, to optimize
its electrical and thermal performance, some layout
considerations are still necessary.
• Use large PCB copper areas for high current paths,
including VIN1, VIN2 , PGND1 and PGND2, VOUT1 and
VOUT2. It helps to minimize the PCB conduction loss
and thermal stress.
4616fa
18
LTM4616
APPLICATIONS INFORMATION
• Place high frequency ceramic input and output capacitors next to the VIN, GND and VOUT pins to minimize
high frequency noise.
• Use a separated SGND ground copper area for components connected to signal pins. Connect the SGND
to GND underneath the unit.
• Place a dedicated power ground layer underneath the
unit.
• For parallel modules, tie the ITH, FB and ITHM pins together. Use an internal layer to closely connect these
pins together. All of the ITHM pins connect to the SGND
of the master regulator, then the master SGND connects
to GND.
• To minimize the via conduction loss and reduce module
thermal stress, use multiple vias for interconnection
between top layer and other power layers.
Figure 17 gives a good example of the recommended
layout.
• Do not put vias directly on the pads, unless they are
capped or plated over.
VIN1
VOUT1
VIA TO GND 2X
CONTROL1
M
COUT2
VOUT1
L
VIN1
CIN1
K
J
H
GND1
GND1
G
CONTROL1 & 2
F
VIN2
COUT2
VOUT2
E
CIN2
D
C
B
GND2
GND2
A
1
2
3
4
5
6
GND2
7
8
9
10
CONTROL2
11
12
GND2
4616 F17
LTM4616 TOP VIEW
Figure 17. Recommended PCB Layout
CLKIN1
CLKIN1
CLKOUT1 CLKIN2
CLKOUT2
SVIN1
FB1
RUN1
ITH1
PGOOD1
MODE1
BSEL1
PHMODE1
TRACK1
10μF
OE
IN
OUT
H
H
L
H
L
X
H
L
Z
MGN
SVIN2
FB2
RUN2
ITH2
PGOOD2
BSEL2
PHMODE2
A2
V+
OUT
6.65k
VOUT2
1.5V/8A
100μF
s2
BSEL
R2
50k
SGND1
GND1
SGND2
GND2
4616 F18
R1
50k
IOE
IIN
GND
5 PIN SC70 PACKAGE
VIN
PGOOD
MGN2
SW2
+ Value of BSEL Selection
H
– Value of BSEL Selection
L
VIN/2 No Margin
R3
50k
ITHM2
TRACK2
MARGIN VALUE
BSEL
R4
50k
VOUT2
VIN2
MODE2
A1, A2 PERICOM P174ST1G126CEX
TOSHIBA TC75Z126AFE
VIN
PGOOD
MGN1
LTM4616
PLLLPF2
BSEL: HIGH = 10%
FLOAT = 15%
LOW = 5%
4.87k
ITHM1
PLLLPF1
VIN2 3V TO 5.5V
VOUT1
1.8V/8A
100μF
VOUT1
A1
V+
OUT
+
–
10μF
VIN1
SW1
+
–
VIN1 3V TO 5.5V
IOE
IIN
GND
5 PIN SC70 PACKAGE
Figure 18. Typical 3.2V to 5VIN, to 1.8V, 1.5V Outputs
4616fa
19
LTM4616
APPLICATIONS INFORMATION
VIN 3V TO 5.5V
VIN1
SW1
CLKIN1
CLKOUT1 CLKIN2
CLKOUT2
10μF
SVIN1
FB1
RUN
ENABLE
RUN1
ITH1
100μF
3.32k
ITHM1
PLLLPF1
PGOOD1
MODE1
BSEL1
PHMODE1
TRACK1
MGN1
LTM4616
VIN2
10μF
VOUT
1.5V/16A
VOUT1
VOUT2
SVIN2
FB2
RUN2
ITH2
100μF
100μF
ITHM2
PLLLPF2
PGOOD2
MODE2
BSEL2
PHMODE2
MGN2
TRACK2
SW2
SGND1
GND1
SGND2
GND2
4616 F19
Figure 19. LTM4616 Two Outputs Parallel, 1.5V at 16A Design
CLKIN
VIN 5V
VIN1
22μF
SHDNB
100k
SW1
CLKIN1
CLKOUT1 CLKIN2
CLKOUT2
SVIN1
FB1
RUN1
ITH1
BSEL1
TRACK1
MGN1
LTM4616
100k
SVIN1
VOUT2
1.5V/8A
VOUT2
SVIN2
FB2
RUN2
ITH2
100μF
6.65k
100μF
ITHM2
PLLLPF2
MODE2
PGOOD1
100μF
PGOOD1
PHMODE1
VIN2
100k
2.21k
ITHM1
PLLLPF1
MODE1
PGOOD2
VOUT1
3.3V/7A
VOUT1
PGOOD2
PHMODE2
BSEL2
TRACK2
MGN2
SW2
SGND1
GND1
SGND2
GND2
100k
SHDNB
3.3V
SVIN2
4616 F20
1.5V
Figure 20. LTM4616 Output Sequencing Application
4616fa
20
LTM4616
APPLICATIONS INFORMATION
SW1
VIN1
10μF
6.3V
CLKIN1
CLKOUT1 CLKIN2
CLKOUT2
SVIN1
ITH1
PGOOD1
MODE1
TRACK1
MGN1
LTM4616
VOUT2
VIN2
SVIN2
FB2
+
C2
470μF
6.3V
+
C3
470μF
6.3V
ITH2
RUN2
PLLLPF2
ITHM2
MODE2
PGOOD2
PHMODE2
BSEL2
TRACK2
VIN1
MGN2
SW2
SGND1
SW1
CLKIN1
GND1
SGND2
CLKOUT1 CLKIN2
GND2
CLKOUT2
SVIN1
VOUT1
FB1
ITH1
RUN1
ITHM1
PLLLPF1
PGOOD1
MODE1
BSEL1
PHMODE1
TRACK1
MGN1
LTM4616
VOUT2
VIN2
10μF
6.3V
SANYO POSCAP
10mΩ
BSEL1
PHMODE1
10μF
6.3V
2.47k
SVIN2
FB2
ITH2
RUN2
+
C5
22μF
6.3V
PHMODE2
BSEL2
TRACK2
MGN2
SW2
SGND1
GND1
SGND2
GND2
4616 F21
R1
50k
R2
50k
IN
OUT
H
H
L
H
L
X
H
L
Z
A1, A2 PERICOM P174ST1G126CEX
TOSHIBA TC75Z126AFE
MGN
C4
22μF
6.3V
PGOOD2
MODE2
OE
+
ITHM2
PLLLPF2
BSEL: HIGH = 10%
FLOAT = 15%
LOW = 5%
VOUT
1.2V AT 32A
C1
470μF
6.3V
ITHM1
PLLLPF1
10μF
6.3V
+
FB1
RUN1
TRACK INPUT
OR 3VIN
VOUT1
MARGIN VALUE
A1
V+
VIN
3V TO 6.6V
OUT
+
–
VIN
3V TO 6.5V
IOE
IIN
GND
6 PIN SC70 PACKAGE
OPTIONAL MARGINING CIRCUIT,
IF NOT USED TIE THE MGN PINS TO VOUT
+ Value of BSEL Selection
H
– Value of BSEL Selection
L
VIN/2 No Margin
Figure 21. Four Phase in Parallel, 1.2V at 32A
4616fa
21
LTM4616
APPLICATIONS INFORMATION
VIN
4V TO 5.5V
VIN1
SW1
CLKIN1
CLKOUT1 CLKIN2
CLKOUT2
10μF
SVIN1
FB1
RUN
ENABLE
RUN1
ITH1
PGOOD1
MODE1
BSEL1
PHMODE1
TRACK1
MGN1
LTM4616
SVIN2
FB2
RUN2
ITH2
PGOOD2
MODE2
BSEL2
PHMODE2
MGN2
TRACK2
3.16k
VIN1
10μF
SW2
SGND1
SW1
CLKIN1
GND1
SGND2
CLKOUT1 CLKIN2
GND2
CLKOUT2
FB1
RUN1
ITH1
BSEL1
TRACK1
MGN1
LTM4616
SVIN2
FB2
RUN2
ITH2
10k
100μF
PGOOD2
MODE2
BSEL2
PHMODE2
MGN2
TRACK2
6.65k
6.65k
ITHM2
PLLLPF2
3.3V
VOUT4
1.5V/8A
100μF
VOUT2
VIN2
10μF
100μF
PGOOD1
PHMODE1
4.99k
4.99k
ITHM1
MODE1
10k
VOUT3
1.8V/8A
100μF
VOUT1
SVIN1
PLLLPF1
3.3V
100μF
3.16k
ITHM2
PLLLPF2
10k
VOUT2
2.5V/8A
VOUT2
VIN2
3.3V
100μF
2.21k
ITHM1
PLLLPF1
10μF
VOUT1
3.3V/7A
VOUT1
SW2
SGND1
GND1
SGND2
GND2
4616 F22
Figure 22. 4-Phase, Four Outputs (3.3V, 2.5V, 1.8V and 1.5V) with Tracking
4616fa
22
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
6.9850
5.7150
4.4450
3.1750
1.9050
0.6350
0.0000
0.6350
1.9050
3.1750
4.4450
5.7150
6.9850
PACKAGE TOP VIEW
3.1750
SUGGESTED PCB LAYOUT
TOP VIEW
1.9050
4
0.6350
0.0000
0.6350
PAD 1
CORNER
15
BSC
1.9050
aaa Z
X
15
BSC
Y
bbb Z
0.27 – 0.37
SUBSTRATE
DETAIL B
DETAILS OF PAD #1 IDENTIFIER ARE OPTIONAL,
BUT MUST BE LOCATED WITHIN THE ZONE INDICATED.
THE PAD #1 IDENTIFIER MAY BE EITHER A MOLD OR
MARKED FEATURE
LAND DESIGNATION PER JESD MO-222, SPP-010
SYMBOL TOLERANCE
aaa
0.10
bbb
0.10
eee
0.05
6. THE TOTAL NUMBER OF PADS: 144
5. PRIMARY DATUM -Z- IS SEATING PLANE
4
3
2. ALL DIMENSIONS ARE IN MILLIMETERS
3
12
11
TRAY PIN 1
BEVEL
COMPONENT
PIN “A1”
PADS
SEE NOTES
1.27
BSC
13.97
BSC
0.12 – 0.28
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994
DETAIL A
Z
eee S X Y
DETAIL B
0.630 ±0.025 SQ. 143x
aaa Z
2.45 – 2.55
MOLD
CAP
2.72 – 2.92
10
7
6
5
LTMXXXXXX
mModule
PACKAGE BOTTOM VIEW
8
13.97
BSC
4
3
2
LGA 144 0308 REV A
1
DETAIL A
PACKAGE IN TRAY LOADING ORIENTATION
9
3x, C (0.22 x45°)
A
B
C
D
E
F
G
H
J
K
L
M
DIA 0.630
PAD 1
LTM4616
PACKAGE DESCRIPTION
LGA Package
144-Lead (15mm × 15mm × 2.82mm)
(Reference LTC DWG # 05-08-1816 Rev A)
4616fa
23
6.9850
5.7150
4.4450
3.1750
4.4450
5.7150
6.9850
LTM4616
PACKAGE DESCRIPTION
Pin Assignment Table
(Arranged by Pin Number)
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
A1
GND1
B1
GND1
C1
VIN1
D1
VIN1
E1
VIN1
F1
VIN1
A2
GND1
B2
GND1
C2
VIN1
D2
VIN1
E2
VIN1
F2
VIN1
A3
GND1
B3
GND1
C3
GND1
D3
GND1
E3
VIN1
F3
VIN1
A4
GND1
B4
GND1
C4
GND1
D4
GND1
E4
VIN1
F4
VIN1
F5
A5
GND1
B5
GND1
C5
GND1
D5
GND1
E5
SVIN1
A6
BSEL1
B6
SW1
C6
GND1
D6
GND1
E6
PLLFLTR1 F6
RUN1
SGND1
A7
CLKIN1
B7
GND1
C7
GND1
D7
GND1
E7
ITHM1
F7
CLKOUT1
A8
MODE1
B8
GND1
C8
GND1
D8
FB1
E8
TRACK1
F8
ITH1
A9
PHMODE1
B9
GND1
C9
GND1
D9
VOUT1
E9
VOUT1
F9
VOUT1
A10 MGN1
B10 GND1
C10 GND1
D10 VOUT1
E10 VOUT1
F10 VOUT1
A11 PGOOD1
B11 GND1
C11 GND1
D11 VOUT1
E11 VOUT1
F11 VOUT1
A12 GND1
B12 GND1
C12 GND1
D12 VOUT1
E12 VOUT1
F12 VOUT1
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
G1
GND2
H1
GND2
J1
VIN2
K1
VIN2
L1
VIN2
M1
VIN2
G2
GND2
H2
GND2
J2
VIN2
K2
VIN2
L2
VIN2
M2
VIN2
G3
GND2
H3
GND2
J3
GND2
K3
GND2
L3
VIN2
M3
VIN2
G4
GND2
H4
GND2
J4
GND2
K4
GND2
L4
VIN2
M4
VIN2
G5
GND2
H5
GND2
J5
GND2
K5
GND2
L5
SVIN2
M5
SGND2
G6
BSEL2
H6
SW2
J6
GND2
K6
GND2
L6
PLLFLTR2 M6
RUN2
G7
CLKIN2
H7
GND2
J7
GND2
K7
GND2
L7
ITHM2
M7
CLKOUT2
G8
MODE2
H8
GND2
J8
GND2
K8
FB2
L8
TRACK2
M8
ITH2
G9
PHMODE2
H9
GND2
J9
GND2
K9
VOUT2
L9
VOUT2
M9
VOUT2
G10 MGN2
H10 GND2
J10 GND2
K10 VOUT2
L10 VOUT2
M10 VOUT2
G11 PGOOD2
H11 GND2
J11 GND2
K11 VOUT2
L11 VOUT2
M11 VOUT2
G12 GND2
H12 GND2
J12 GND2
K12 VOUT2
L12 VOUT2
M12 VOUT2
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC2900
Quad Supply Monitor with Adjustable Reset Timer
Monitors Four Supplies; Adjustable Reset Timer
LTM4600
10A DC/DC μModule
Basic 10A DC/DC μModule, LGA Package
LTM4600HVMP
Military Plastic 10A DC/DC μModule
Guaranteed Operation from –55°C to 125°C Ambient, LGA Package
LTM4601/
LTM4601A
12A DC/DC μModule with PLL, Output Tracking/
Margining and Remote Sensing
Synchronizable, PolyPhase Operation, LTM4601-1/LTM4601A-1 Version has no
Remote Sensing, LGA Package
LTM4602
6A DC/DC μModule
Pin Compatible with the LTM4600, LGA Package
LTM4603
6A DC/DC μModule with PLL and Outpupt Tracking/ Synchronizable, PolyPhase Operation, LTM4603-1 Version has no Remote
Margining and Remote Sensing
Sensing, Pin Compatible with the LTM4601, LGA Package
LTM4604A
Low VIN 4A DC/DC μModule
2.375V ≤ VIN ≤ 5.5V, 0.8V ≤ VOUT ≤ 5V, 9mm × 15mm × 2.3mm LGA Package
LTM4608A
Low VIN 8A DC/DC μModule
2.7V ≤ VIN ≤ 5.5V; 0.6V ≤ VOUT ≤ 5V; 9mm × 15mm × 2.8mm LGA Package
LTM8022/LTM8023 36VIN, 1A and 2A DC/DC μModule
Pin Compatible; 4.5V ≤ VIN ≤ 36V; 9mm × 11.25mm × 2.8mm LGA Package
4616fa
24 Linear Technology Corporation
LT 1108 REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2008