E-L6919ETR STMicroelectronics, E-L6919ETR Datasheet - Page 12

• 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

L6919E
1. T
This happens when the maximum ON time is reached before the current in each phase reaches I
< 35 A).
Figure 5a shows the maximum output voltage that the device is able to regulate considering the T
imposed by the previous relationship. If the desired output characteristic crosses the T
Figure 5. T
2. Constant Current Operation
This happens when ON time limitation is reached after the current in each phase reaches I
The device enters in Quasi-Constant-Current operation: the low-side mosfets stays ON until the current read
becomes lower than I
a T
another OCP event is detected.
This means that the average current delivered can slightly increase also in Over Current condition since the cur-
rent ripple increases. In fact, the ON time increases due to the OFF time rise because of the current has to reach
the I
When this happens, the device works in Constant Current and the output voltage decrease as the load increase.
Crossing the UVP threshold causes the device to latch (FAULT pin is driven high).
Figure 6 shows this working condition
It can be observed that the peak current (Ipeak) is greater than the I
Where V
The device works in Constant-Current, and the output voltage decreases as the load increase, until the output
voltage reaches the Under-Voltage threshold (V
off, the FAULT pin is driven high and the device stops working. Cycle the power supply to restart operation. The
maximum average current during the Constant-Current behavior results:
12/33
voltage, the output resulting voltage will start to drop after crossing. In this case, the device doesn't perform con-
stant current limitation but only limits the maximum ON time following the previous relationship. The output volt-
age follows the resulting characteristic (dotted in Figure 5b) until UVP is detected or anyway until I
ON
ON
OCPx
0.80·V
0.40·V
imposed by the control loop at the next available clock cycle and the device works in the usual way until
Limited Output Voltage.
V
outMIN
OUT
bottom. The worst-case condition is when the ON time reaches its maximum value.
IN
IN
a) Maximum output Voltage
ON
Ipea k
is the minimum output voltage (VID-30% as follow).
Limited Operation
T
=
ON
OCPx
Limited Output
I
OCPx
characteristic
(I
I
INFOx
M AX,TOT
+
V
-------------------------------------- - Ton
I
IN
< 35 A) skipping clock cycles. The high side mosfets can be turned ON with
(I
OCP
FB
=2·I
=70 A)
–
Vo ut
OCPx
=
L
2 I
I
M IN
OUT
MA X
outMIN
+
2
). When this threshold is crossed, all mosfets are turned
M AX


I
OCPx
=
0.80·V
0.40·V
I
OCPx
+
V
OUT
Ipe ak I
------------------------------------- -
IN
IN
b) T
OCPx
+
V
-------------------------------------- - 0.40 T
ON
2
–
but it can be determined as follow:
IN
Limited Output Voltage
OCP x
–
Vo ut
L


M IN
ON
limited maximum output
I
OCPx
(I
OCP
FB
=70 A)
=2·I
characteristic and
Resulting Output
OCPx
Desired Output
UVP threshold
(I
characteristic
INFOx
FB
OCPx
ON
I
OUT
= 70 A.
limitation
>35 A).
(I
INFOx