EVAL5985 STMicroelectronics, EVAL5985 Datasheet - Page 17

• Manufacturer Part Number: EVAL5985
• Description: BOARD EVAL FOR L5985
• Manufacturer: STMicroelectronics
• Type: DC/DC Switching Converters, Regulators & Controllersr

Specifications of EVAL5985

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Non-Isolated
• Voltage - Output: 3.3V
• Current - Output: 2A
• Voltage - Input: 3.3 ~ 18V
• Regulator Topology: Buck
• Frequency - Switching: 500kHz
• Board Type: Fully Populated
• Utilized Ic / Part: L5985
• Input Voltage: 2.9 V to 18 V
• Output Voltage: 0.6 V to 16 V
• Product: Power Management Modules
• Silicon Manufacturer: ST Micro
• Silicon Core Number: L5985
• Kit Application Type: Power Management - Voltage Regulator
• Application Sub Type: Step Down Switching Regulator
• Kit Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• For Use With/related Products: L5985
• Other names: 497-6387; EVAL5985

L5985
5.4
Table 8.
Compensation network
The compensation network has to assure stability and good dynamic performance. The loop
of the L5985 is based on the voltage mode control. The error amplifier is a voltage
operational amplifier with high bandwidth. So selecting the compensation network the E/A
will be considered as ideal, that is, its bandwidth is much larger than the system one.
The transfer functions of PWM modulator and the output LC filter are studied. (see
The transfer of the function PWM modulator, from the error amplifier output (COMP pin) to
the OUT pin, results:
Equation 10
where V
generates a sawtooth amplitude directly proportional to the input voltage, that is:
Equation 11
In this way the PWM modulator gain results constant and equals to:
Equation 12
The synchronization of the device with an external clock provided trough SYNCH pin can
modifies the PWM modulator gain (see
and how to keep it constant in spite of the external synchronization)
Manufacturer
PANASONIC
MURATA
SANYO
TDK
S
is the sawtooth amplitude. As seen in
Output capacitors
GRM32
GRM31
ECJ
EEFCD
TPA/B/C
C3225
Series
Doc ID 13006 Rev 5
G
22 to 100
10 to 47
10 to 22
10 to 68
100 to 470
22 to 100
PW0
Cap value (μF)
Chapter 4.1
G
V
S
PW0
=
=
V
-------- -
V
IN
K V
s
=
⋅
Chapter
=
V
-------- -
V
IN
IN
s
--- -
K
1
to understand how this gain changes
=
9
6.3 to 25
6.3 to 25
6.3
6.3
4 to 16
6.3
Rated voltage (V)
4.1, the voltage feed forward
Application information
< 5
< 5
< 5
15 to 55
40 to 80
< 5
ESR (mΩ)
Figure
17/37
9)