E-L6919ETR STMicroelectronics, E-L6919ETR Datasheet - Page 15

• Manufacturer Part Number: E-L6919ETR
• Description: IC CTRLR 5BIT PROG 2PHASE 28SOIC
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of E-L6919ETR

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 0.8 ~ 1.55 V
• Current - Output: 2A
• Frequency - Switching: 150kHz
• Voltage - Input: 5 ~ 12 V
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: 28-SOIC (7.5mm Width)
• Power - Output: 2W
• Mounting Style: SMD/SMT
• Operating Supply Voltage: 6.5 V
• Maximum Operating Temperature: 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-4592-2

Figure 9. - Remote Buffer Connections
OUTPUT VOLTAGE MONITOR AND PROTECTIONS
The device monitors through pin VSEN the regulated voltage in order to build the PGOOD signal and manage
the OVP / UVP conditions.
Power good output is forced low if the voltage sensed by VSEN is not within ±12% (Typ.) of the programmed
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 ref-
erence 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: when the voltage monitored by VSEN reaches the OVP threshold
VOVP the controller permanently switches on both the low-side mosfets and switches off both the high-side
mosfets in order to protect the load. The OSC/ FAULT pin is driven high (5V) and power supply (Vcc) turn off
and on is required to restart operations.
The over voltage percentage is then set by the ratio between the fixed OVP threshold VOVP and the reference
programmed by VID:
Both Over Voltage and Under Voltage are active also during soft start (Under Voltage after than the output volt-
age 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.
SOFT START AND INHIBIT
At start-up a ramp is generated increasing the loop reference from 0V to the final value programmed by VID in
2048 clock periods as shown in figure 10.
Once the soft start begins, the reference is increased: upper and lower MOS begin to switch and the output volt-
age starts to increase with closed loop regulation. At the end of the digital soft start, the Power Good comparator
is enabled and the PGOOD signal is then driven high (See fig. 10). The Under Voltage comparator is enabled
when the reference voltage reaches 0.6V. The Soft-Start will not take place, if both VCC and VCCDR pins are
not above their own turn-on thresholds.
During normal operation, if any under-voltage is detected on one of the two supplies the device shuts down.
Forcing the OSC/INH pin to a voltage lower than 0.6V (Typ.) disables the device: all the power mosfets and
protections are turned off until the condition is removed.
Remote
V
64k
64k
FBR
OUT
RB used (±0.5% Accuracy)
FBG
64k
Remote
Ground
64k
REMOTE
BUFFER
VSEN
O VP %
R
FB
I
Reference
FB
FB
C
=
F
AMPLIFIER
---------------------------------------------------------------------- - 100
Re feren ceVo ltage VID
ERROR
R
F
COMP
V
O VP
64k
64k
FBR
FBG
64k
64k
REMOTE
BUFFER
RB Not Used
VSEN
V
OUT
R
FB
I
FB
Reference
FB
C
F
AMPLIFIER
ERROR
R
F
COMP
L6919E
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