E-L6911C STMicroelectronics, E-L6911C Datasheet - Page 12

• Manufacturer Part Number: E-L6911C
• Description: IC CTRLR 5BIT PROGR STPDN 20SOIC
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of E-L6911C

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 1
• Voltage - Output: 1.3 ~ 3.5 V
• Current - Output: 1.3A
• Frequency - Switching: 200kHz
• Voltage - Input: 5 ~ 12 V
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: 20-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

L6911C
Where I
Therefore, with the droop function the output voltage decreases as the load current increases, so the DC output
impedance is equal to a resistance R
sient is minimum when the output impedance is constant with frequency.
To choose the other components of the compensation network, the transfer function of the voltage loop is con-
sidered. To simplify the analysis is supposed that R3 << Rd, where Rd = (R8//R9).
Figure 8. Compensation network definition
The transfer function may be evaluated neglecting the connection of R8 to PHASE because, as will see later,
this connection is important only at low frequencies. So R4 is considered connected to VOUT. Under this as-
sumption, the voltage loop has the following transfer function:
12/20
From the above equations, it results:
The component R3 must be chosen in order to obtain R3<<R8//R9 to permit these and successive
simplifications.
ConverterS
MAX
is the maximum output current.
ingularity
|G lo o p |
f
f
f
f
LC
CE
EC
CC
|A v |
|R |
R
G
/ 1
/ 1
/ 1
/ 1
0
0
2
2
2
2
ESR
Rceramic
ESR
LC
f
D
R9
Cceramic
C
OUT
OUT
Cceramic
=
R8
R8
. It is easy to verify that the output voltage deviation under load tran-
f
f
L C
2
2
=
-------------------------- -
-----------------------
R
doublepole
ESRzero
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CeramicCap
V
V
V
L
PRO G
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f
I
f
C E
1
M AX
R 2
by
acitor
-------------------------- -
R
Compensati
------------------------------------ -
1
V
L
+
DROOP
fc
-------------------------- -
I
R
M AX
V
L
1
onNetworkS
DROOP
I
f
M AX
E C
;
f
3
ingularity
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/ 1
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R
(
R
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R
4
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C
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R
25
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C
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