DN524 - Dual 13A μModule Regulator with Digital Interface for Remote Monitoring & Control of Power

Dual 13A μModule Regulator with Digital Interface for
Remote Monitoring & Control of Power
Design Note 524
Jian Li and Gina Le
standard I2C-based digital serial interface protocol.
The LTM4676 combines best-in-class analog switching regulator performance with precision mixed signal
data acquisition. It features ±1% maximum DC output
voltage error and ±2.5% current read back accuracy
over temperature (TJ = –40ºC to 125ºC), and integrated
16-bit delta-sigma ADC and EEPROM.
Digital Power System Management:
Set, Monitor, Change and Log Power
Managing power and implementing flexibility in a high
rail count circuit board can be challenging, requiring
hands-on probing with digital voltmeters and oscilloscopes, and often rework of PCB components. To
simplify power management, especially from a remote
location, there is a trend to configure and monitor
power via a digital communications bus. Digital power
system management (PSM) enables on-demand telemetry capability to set, monitor, change and log
power parameters.
The LTM4676’s 2-wire serial interface allows outputs
to be margined, tuned and ramped up and down at
programmable slew rates with sequencing delay times.
Input and output currents and voltages, output power,
temperature, uptime and peak values are readable.
The device is comprised of fast, dual analog control
loops, precision mixed signal circuitry, EEPROM, power
MOSFETs, inductors and supporting components
housed in a 16mm × 16mm × 5.01mm BGA (ball grid
array) package.
Dual µModule® Regulator with Precision
READ/WRITE of Power Parameters
The LTM®4676 is a dual 13A output constant frequency
switching mode DC/DC µModule (micromodule)
regulator (Figure 1). In addition to delivering power
at a point-of-load, the LTM4676 features configurability and telemetry-monitoring of power and power
management parameters over PMBus— an open
CINH
22µF
×3
10k
×9
SMBus INTERFACE WITH
PMBus COMMAND SET
ON/OFF CONTROL, FAULT
MANAGEMENT, POWER
SEQUENCING
PWM CLOCK SYNCH.
TIME BASE SYNCH.
• SLAVE ADDRESS = 1001111_R/W (0x4F)
• SWITCHING FREQUENCY: 350kHz
• NO GUI CONFIGURATION AND
NO PART SPECIFIC PROGRAMMING REQUIRED
* FOR 4.5VIN, CONNECT INTVCC TO VIN
VIN0
VIN1
SVIN
VOUT0
TSNS0a
TSNS0b
ISNS0a+
ISNS0b+
ISNS0a–
ISNS0b–
VOSNS0+
VOSNS0–
VDD33
SCL
SDA
ALERT
RUN0
RUN1
GPIO0
GPIO1
SYNC
SHARE_CLK
WP
LTM4676
22.6k
1%
±50ppm/°C
VOUT1
TSNS1a
TSNS1b
ISNS1a+
ISNS1b+
ISNS1a–
ISNS1b–
VOSNS1
SGND
COUT0
100µF
×7
COUT1
100µF
×7
LOAD1
6.34k
1%
±50ppm/°C
Figure 1. LTM4676: Dual 13A Output µModule Regulator with PMBus Interface
03/14/524
VOUT0, 1.0V
ADJUSTABLE
UP TO 13A
LOAD0
GND
CINL
220µF
INTVCC
VDD25
SW0
SW1
SNUB0
SNUB1
+
COMP0a
COMP0b
COMP1a
COMP1b
ASEL
FSWPHCFG
VOUT0CFG
VTRIM0CFG
VOUT1CFG
VTRIM1CFG
VIN
5.75V* TO 26.5V
L, LT, LTC, LTM, Linear Technology, the Linear logo and µModule are
registered trademarks and LTpowerPlay is a trademark of Linear Technology
Corporation. All other trademarks are the property of their respective owners.
VOUT1, 1.8V
ADJUSTABLE
UP TO 13A
The LTM4676 operates from a 4.5V to 26.5V input
supply and steps down VIN to two outputs ranging
from 0.5V to 5.4V. Two outputs can current share
to provide up to 26A (i.e., 13A + 13A as one output).
Internal or External Compensation
The LTM4676 offers both internal or external compensation, which can optimize the transient response
over a wide operating range. Figure 2 shows that the
peak-to-peak output voltage is only 94mV with a 50%
load step.
ing among multiple phases. Paralleling modules can
achieve much higher output current capability. For
example, four LTM4676 µModule regulators can be
paralleled to provide up to 100A output current. Figure 3
shows the thermal picture. With 300LFM of airflow,
the hot spot temperature rise is only 64.3°C. The
even thermal distribution among modules is due
to excellent current sharing performance. Figure 4
is a photo of the demo board with four LTM4676
µModule regulators assembled to provide 100A at 1V.
VPP = 94mV
VO
(50mV/DIV)
IO = 6.5 ~ 13A
IO
(5A/DIV)
dn4jlgl F02
Figure 2. Transient Response of the LTM4676 in Figure 1
at VIN = 12V, VOUT1 = 1.8V, IO = 6.5A ~ 13A
Figure 4. Four LTM4676, Each in a 16mm × 16mm ×
5.01mm LGA Package Deliver 100A at 1VOUT.
Conclusion
Linear Technology’s digital power system management
(PSM) products provide users with critical power-related
data. One can access load current, input current, output
voltages, compute power consumption, efficiency, and
access other power management parameters via a
digital bus. This enables predictive analytics, minimizes
operating costs, increases reliability and ensures smart
energy management decisions can be made.
Figure 3. Four LTM4676 Current Sharing: Thermal
Picture at VIN = 12V, VOUT = 1.0V/100A, 300LFM Airflow
Current Share for up to 100A at 1VOUT
The LTM4676 uses a constant frequency peak
current mode control architecture, which offers a
cycle-by-cycle current limit and easy current sharData Sheet Download
www.linear.com/LTM4676
Linear Technology Corporation
On-demand digital control and monitoring of system
power with the LTM4676 eliminates PCB layout and
circuit component manipulation and accelerates system characterization, optimization and data mining
during prototyping, deployment and field operation.
For demo kits, free download of the LTPowerPlay™ GUI
and PSM training videos, please visit www.linear.com
and type “PSM” in the SEARCH box.
For applications help,
call (408) 432-1900, Ext. 3578
dn524 LT/AP 0314 111K • PRINTED IN THE USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2014