L6728ATR STMicroelectronics, L6728ATR Datasheet - Page 12
L6728ATR
Manufacturer Part Number
L6728ATR
Description
IC CTLR PWM SGL HI FREQ 10VFQFPN
Manufacturer
STMicroelectronics
Datasheet
1.L6728ATR.pdf
(32 pages)
Specifications of L6728ATR
Pwm Type
Voltage Mode
Number Of Outputs
1
Frequency - Max
660kHz
Duty Cycle
67%
Voltage - Supply
5 V ~ 12 V
Buck
Yes
Boost
No
Flyback
No
Inverting
No
Doubler
No
Divider
No
Cuk
No
Isolated
No
Operating Temperature
-40°C ~ 125°C
Package / Case
10-DFN
Frequency-max
660kHz
Topology
Buck
Output Voltage
0.8 V
Output Current
1500 mA
Switching Frequency
660 KHz
Duty Cycle (max)
67 %
Maximum Operating Temperature
+ 125 C
Minimum Operating Temperature
- 40 C
Synchronous Pin
No
For Use With
497-8228 - BOARD EVALUATION W/L6728497-6418 - BOARD EVAL BASED ON L6728
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
497-8324-2
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
L6728A
7
7.1
Over-current protection
The over-current function protects the converter from a shorted output or overload, by
sensing the output current information across the low side MOSFET drain-source on-
resistance, R
avoiding the use of expensive and space-consuming sense resistors.
The low side R
node when LS MOSFET is turned on with the programmed OCP thresholds voltages,
internally held. If the monitored voltage is bigger than these thresholds, an over-current
event is detected.
For maximum safety and load protection, L6728A implements a dual level over-current
protection system:
●
●
When over-current protection is triggered, the device turns off both LS and HS MOSFETs in
a latched condition.
To recover from over-current protection triggered condition, V
cycled.
Over-current threshold setting
L6728A allows to easily program a 1
550 mV, simply by adding a resistor (R
will be automatically set accordingly.
During a short period of time (about 5 ms) following
internal 10 µA current (I
across R
level over-current threshold. The OC setting procedure overall time length is about 5 ms.
Connecting a R
threshold will be:
the programmed 2
In case R
values: an internal safety clamp on LGATE is triggered as soon as LGATE voltage reaches
600 mV, setting the maximum threshold and suddenly ending OC setting phase.
1
PHASE exceeds this threshold, a 1
events are detected in four consecutive switching cycles, over-current protection will be
triggered.
2
threshold multiplied by a factor 1.5. If the monitored voltage on PHASE exceeds this
threshold, over-current protection will be triggered immediately.
st
nd
level threshold: it is the user externally set threshold. If the monitored voltage on
level threshold: it is an internal threshold whose value is equal to 1
OCSET
OCSET
DS(on)
DS(on)
. This voltage drop will be sampled and internally held by the device as 1
OCSET
is not connected, the device sets the OCP thresholds to the maximum
nd
. This method reduces cost and enhances converter efficiency by
current sense is implemented by comparing the voltage at the PHASE
level threshold will be:
resistor between LGATE and GND, the programmed 1
OCSET
I
OCth2
I
) is sourced from LGATE pin, determining a voltage drop
OCth1
=
st
OCSET
level over-current threshold ranging from 50 mV to
=
1.5
st
I
------------------------------------------- -
level over-current is detected. If four 1
OCSET
⋅
) between LGATE and GND. 2
I
------------------------------------------- -
OCSET
R
dsON
⋅
R
R
V
dsON
CC
⋅
OCSET
R
rising over UVLO threshold, an
OCSET
CC
power supply must be
Over-current protection
nd
st
level threshold
st
level
level
st
level OC
12/32
st