L6710 STMicroelectronics, L6710 Datasheet - Page 16

• Manufacturer Part Number: L6710
• Description: IC CTRLR 6BIT 2PH PROGR 44-TQFP
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of L6710

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: 0.84 ~ 1.6 V
• Current - Output: 2A
• Frequency - Switching: 150kHz
• Voltage - Input: 12V
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 44-TQFP, 44-VQFP
• Power - Output: 2.5W
• Product: Half-Bridge Drivers
• Supply Current: 12.5 mA
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

L6710
is used for a VRM module. The very low offset amplifier senses the output voltage remotely through the
pins FBR and FBG (FBR is for the regulated voltage sense while FBG is for the ground sense) and reports
this voltage internally at VSEN pin with unity gain eliminating the errors. Keeping the FBR and FBG traces
parallel and guarded by a power plane results in common mode coupling for any picked-up noise.
If remote sense is not required, it is enough connecting R
comes not connected and still senses the output voltage through the remote buffer. In this case the FBG
and FBR pins must be connected anyway to the regulated voltage (See figure 9).
The remote buffer is included in the trimming chain in order to achieve ±0.5% accuracy on the output volt-
age when the RB Is used: eliminating it from the control loop causes the regulation error to be increased
by the RB offset worsening the device performances.
Figure 8. Remote Buffer Connections
OUTPUT VOLTAGE MONITOR PROTECTION
The device monitors through pin VSEN the regulated voltage in order to build the PGOOD signal and man-
age the OVP / UVP conditions comparing this voltage level with the programmed reference VID*.
Power good output is forced low if the voltage sensed by VSEN is not within ±12% (Typ.) of the pro-
grammed value. It is an open drain output and it is enabled only after the soft start is finished (2048 clock
cycles after start-up). During Soft-Start this pin is forced low.
Under voltage protection is provided. If the output voltage monitored by VSEN drops below the 60% of the
reference voltage for more than one clock period, the device turns off all mosfets and the OSC/FAULT is
driven high (5V). The condition is latched, to recover it is required to cycle the power supply.
Over Voltage protection is also provided:
Once VCC crosses the turn-ON threshold, when the voltage monitored by VSEN reaches 125% (Typ.) of
the programmed voltage the controller permanently switches on both the low-side mosfets and switches
off both the high-side mosfets in order to protect the CPU. The OSC/ FAULT pin is driven high (5V) and
power supply (Vcc) turn off and on is required to restart operations.
Both Over Voltage and Under Voltage are active also during soft start (Under Voltage after than the output
voltage reaches 0.6V). The reference used in this case to determine the UV thresholds is the increasing
voltage driven by the 2048 soft start digital counter while the reference used for the OV threshold is the
final reference programmed by the VID pins.
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Remote
V
32k
32k
OUT
FBR
RB used (±0.5% Accuracy)
FBG
32k
Remote
Ground
32k
REMOTE
BUFFER
VSEN
R
FB
I
Reference
FB
FB
C
F
AMPLIFIER
ERROR
R
F
COMP
FB
32k
32k
FBR
directly to the regulated voltage: VSEN be-
FBG
32k
32k
REMOTE
BUFFER
RB Not Used
VSEN
V
OUT
R
FB
I
FB
Reference
FB
C
F
AMPLIFIER
ERROR
R
F
COMP