L6730C ,Adjustable step-down controller with synchronous rectificationElectrical characteristics . . . . . . 105 Device description . . . . 135.1 Oscillator ..
L6730TR ,Adjustable step-down controller with synchronous rectificationFeatures■ Input voltage range from 1.8 V to 14 V ■ Supply voltage range from 4.5 V to 14 V■ Adjusta ..
L6731D ,Adjustable step-down controller with synchronous rectification dedicated to DDR memoryElectrical characteristics . . . . . 85 Device description . 105.1 Oscillator . 1 ..
L6731DTR ,Adjustable step-down controller with synchronous rectification dedicated to DDR memoryApplications■ High current embedded drivers ■ Predictive anti-cross conduction control ■ High perfo ..
L6732 ,Adjustable step-down controller with synchronous rectificationElectrical characteristics . . . . . 85 Device description . 105.1 Oscillator . 1 ..
L6738 ,Single Phase PWM Controller with Light-Load Efficiency OptimizationElectrical characteristics . . . . . . 124 Device description and operation . . . . . 135 S ..
LC4064V-75T44C , 3.3V/2.5V/1.8V In-System Programmable SuperFAST High Density PLDs
LC4064V-75T48C , 3.3V/2.5V/1.8V In-System Programmable SuperFAST High Density PLDs
LC4064V-75T48C , 3.3V/2.5V/1.8V In-System Programmable SuperFAST High Density PLDs
LC4064V-75T48I , 3.3V/2.5V/1.8V In-System Programmable SuperFAST High Density PLDs
LC4064V-75TN100I , 3.3V/2.5V/1.8V In-System Programmable SuperFAST High Density PLDs
LC4064V-75TN44C , 3.3V/2.5V/1.8V In-System Programmable SuperFAST High Density PLDs
L6730C
Adjustable step-down controller with synchronous rectification
Target SpecificationJune 2006 Rev 2 1/50
L6730C
L6730DAdjustable step-down controller with synchronous rectification
Features Input voltage range from 1.8V to 14V Supply voltage range from 4.5V to 14V Adjustable output voltage down to 0.6V with
±0.8% accuracy over line voltage and
temperature (0°C~125°C) Fixed frequency voltage mode control TON lower than 100ns 0% to 100% duty cycle Selectable 0.6V or 1.2V internal voltage
reference External input voltage reference Soft-start and inhibit High current embedded drivers Predictive anti-crossconduction control Selectable UVLO threshold (5V or 12V bus) Programmable high-side and low-side RDS(on)
sense over-current-protection Switching frequency programmable from
100KHz to 1MHz Master/slave synchronization with 180° phase
shift Pre-bias start up capability (L6730C) Selectable source/sink or source only
capability after soft-start (L6730C) Selectable constant current or hiccup mode
overcurrent protection after soft-start (L6730D) Power good output with programmable delay Over voltage protection with selectable
latched/not-latched mode Thermal shut-down Package: HTSSOP20, QFN4x4 24L
Applications High performance / high density DC-DC
modules Low voltage distributed DC-DC niPOL converters DDR memory supply DDR memory bus termination supply
Order Codes
Contents
L6730C - L6730D2/50
Contents Summary description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.1 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Electrical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62.1 Maximum rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Pin connections and functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Device description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135.1 Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.2 Internal LDO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.3 Bypassing the LDO to avoid the voltage drop with low Vcc . . . . . . . . . . . . . 14
5.4 Internal and external references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.5 Error amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
5.6 Soft start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
5.7 Driver section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
5.8 Monitoring and protections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
5.9 Adjustable masking time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
5.10 Multifunction pin (S/O/U L6730C) (CC/O/U L6730D) . . . . . . . . . . . . . . . . . . 25
5.11 Synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
5.12 Thermal shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.13 Minimum on-time (TON, MIN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
5.14 Bootstrap anti-discharging system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5.14.1 Fan’s power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
5.14.2 No-sink at zero current operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
L6730C - L6730D Contents
3/50
Application details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306.1 Inductor design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
6.2 Output capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.3 Input capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
6.4 Compensation network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
6.5 Two quadrant or one quadrant operation mode (L6730C) . . . . . . . . . . . . . . 34
L6730 Demoboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 357.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.2 PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
I/O Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Efficiency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 POL Demoboard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4410.1 Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Summary description L6730C - L6730D
4/50
1 Summary description
The controller is an integrated circuit realized in BCD5 (BiCMOS-DMOS, version 5) fabrication
that provides complete control logic and protection for high performance step-down DC-DC and
niPOL converters.
It is designed to drive N-Channel MOSFETs in a synchronous rectified buck topology. The
output voltage of the converter can be precisely regulated down to 600mV with a maximum
tolerance of ±0.8% or to 1.2V, when one of the internal references is used. It is also possible to
use an external reference from 0V to 2.5V. The input voltage can range from 1.8V to 14V , while
the supply voltage can range from 4.5V to 14V. High peak current gate drivers provide for fast
switching to the external power section and the output current can be in excess of 20A,
depending on the number of the external MOSFETs used. The PWM duty cycle can range from
0% to 100% with a minimum on-time (TON, MIN) lower than 100ns making possible conversions
with very low duty cycle and very high switching frequency.
The device provides voltage-mode control. It includes a 400KHz free-running oscillator that is
adjustable from 100KHz to 1MHz. The error amplifier features a 10MHz gain-bandwidth-
product and 5V/µs slew-rate that permits to realize high converter bandwidth for fast transient
response. The device monitors the current by using the RDS(on) of both the high-side and low-
side MOSFET(s), eliminating the need for a current sensing resistor and guaranteeing an
effective over-current-protection in all the application conditions. When necessary, two different
current limit protections can be externally set through two external resistors. A leading edge
adjustable blanking time is also available to avoid false over-current-protection (OCP)
interventions in every application condition. It is possible to select the HICCUP mode or the
constant current protection (L6730D) after the soft-start phase.
During the soft-start phase a constant current protection is provided. It is possible to select
(before the device turn-on) the sink-source or the source-only mode capability by acting on a
multifunction pin (L6730C). The L6730C disables the sink mode capability during the soft-start
in order to allow a proper start-up also in pre-biased output voltage conditions. The L6730D can
always sink current and so it can be used to supply the DDR Memory BUS termination. Other
features are Master-Slave synchronization (with 180° phase shift), Power-Good with adjustable
delay, over-voltage-protection, feed-back disconnection, selectable UVLO threshold (5V and
12V Bus) and thermal shutdown. The HTSSOP20 package allows the realization of really
compact DC/DC converters.
L6730C - L6730D Summary description
5/50
1.1 Functional description
Note: In the L6730D the multifunction pin is: CC/OVP/UVLO.
Figure 1. Block diagram
