L5983TR STMicroelectronics, L5983TR Datasheet - Page 19

• Manufacturer Part Number: L5983TR
• Description: IC REG SW 1.5A STEPDOWN 8-VFQFPN
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of L5983TR

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Voltage - Output: 0.6 ~ 18 V
• Current - Output: 1.5A
• Frequency - Switching: 250kHz ~ 1MHz
• Voltage - Input: 2.9 ~ 18 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-VFQFN, 8-VFQFPN
• Power - Output: 1.5W
• For Use With: 497-6386 - BOARD EVAL FOR L5983
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 497-6860-2; L5983TR

L5983
5.4.1
Equation 15
As seen in
following paragraphs the guidelines to select the type II and type III compensation network
are illustrated.
Figure 9.
Type III compensation network
The methodology to stabilize the loop consists of placing two zeros to compensate the effect
of the LC double pole, therefore increasing phase margin; then to place one pole in the
origin to minimize the DC error on regulated output voltage; finally to place other poles far
from the zero dB frequency.
If the equivalent series resistance (ESR) of the output capacitor introduces a zero with a
frequency higher than the desired bandwidth (that is: 2π * ESR * C
compensation network is needed. Multi layer ceramic capacitors (MLCC) have very low ESR
(<1 mΩ), with very high frequency zero, so a type III network is adopted to compensate the
loop.
In
(f
Equation 16
Equation 17
Z1
Figure 10
, f
Z2
) and three poles (f
Section
V
V
FB
FB
the type III compensation network is shown. This network introduces two zeros
Error amplifier, PWM modulator and LC output filter
REF
REF
Q
4.3, two different kinds of network can compensate the loop. In the two
E/A
E/A
=
f
P0
----------------------------------------------------------------------------------------- -
R
=
f
V
V
Z1
OUT
0
S
S
COMP
COMP
P0
,
L
=
, f
+
----------------------------------------------- -
2π C
⋅
Doc ID 13005 Rev 7
L C
C
P1
f
P1
OUT
⋅
⋅
, f
G
G
=
OUT
P2
3
PW0
PW0
⋅
⋅
----------------------------- -
2π R
). They are expressed as:
R
1
(
R
OUT
⋅
PWM
PWM
⋅
1
(
R
1
+
3
OUT
R
⋅
⋅
E SR
C
3
)
3
,
+
,
ESR
f
Z2
f
P2
)
,
=
=
V
V
----------------------------- -
2π R
CC
CC
------------------------------------------- -
2π R
OUT
OUT
⋅
⋅
1
R
4
4
OUT
⋅
1
⋅
C
G
G
------------------- -
C
C
4
LC
LC
4
4
=
OUT
Application information
L
L
+
⋅
V
--------------
I
C
C
OUT
OUT
5
5
< 1 /BW), the type III
ESR
ESR
C
C
OUT
OUT
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