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PDF SiP12116 Data sheet ( Hoja de datos )
| Número de pieza | SiP12116 | |
| Descripción | 3A Current Mode Constant On-Time Synchronous Buck Regulator | |
| Fabricantes | Vishay | |
| Logotipo |  |
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SiP12116
Vishay Siliconix
3 A Current Mode Constant On-Time
Synchronous Buck Regulator
DESCRIPTION
The SiP12116 is a high frequency current-mode constant
on-time (CM-COT) synchronous buck regulator with
integrated high-side and low-side power MOSFETs. Its
power stage is capable of supplying up to 3 A continuous
current at 600 kHz switching frequency. This regulator
produces an adjustable output voltage down to 0.6 V from
4.5 V to 15 V input rail to accommodate a variety of
applications, including consumer electronics, computing,
telecom, and industrial.
SiP12116’s CM-COT architecture delivers ultrafast transient
response and low ripple over the full load range with
minimum output capacitance and no ESR requirements.
The device features a built in soft start of 2.2 ms and
integrated compensation.
The device also includes cycle-by-cycle current limit, over
temperature protection (OTP) and input under-voltage
lockout (UVLO).
The SiP12116 is available in lead (Pb)-free 3 mm x 3 mm
DFN 10 lead package with thermal pad.
FEATURES
• 4.5 V to 15 V input voltage
• Adjustable output voltage down to 0.6 V
• 3 A continuous output current
• Integrated compensation
• 600 kHz switching frequency
• Ultrafast transient response
• < 5 μA typical shutdown current
• Cycle by cycle current limit
• Power good function
• Fixed soft start: 2.9 ms, typ.
• Material categorization: for definitions of compliance
please see www.vishay.com/doc?99912
APPLICATIONS
• Graphics cards
• Set -top- box
• LCD TV
• Notebook computers
• HDD / SSD
TYPICAL APPLICATION CIRCUIT AND PACKAGE OPTIONS
Input
4.5 V to 15 V
Enable
Power good
PGOOD
VIN
EN BOOT
LX
VCC
SiP12116
FB
VOUT
PGND
Fig. 1 - Typical Application Circuit for SiP12116
S17-0308-Rev. C, 06-Mar-17
1
Document Number: 62969
For technical questions, contact: [email protected]
THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT
ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
1 page  
www.vishay.com
FUNCTIONAL BLOCK DIAGRAM
SiP12116
Vishay Siliconix
SOFT
START
1
VFB
Isense
+
+ OTA
-
I- V
Converter
PAD
2
Vcc
9
PGOOD
10
EN
0.6V
REFERENCE
UVLO
OTP
REGULATOR
Boot
3
VIN
Boot
8
+
-
PWM COMPARATOR
ON -TIME
GENERATOR
CONTROL
LOGIC
SECTION
ANTI-XCOND
CONTROL
VCC
VFB
0.3V
-
+
NEG
CURRENT
SENSING
OCP
Isense
Current
Mirror
LX
6,7
PGND
4,5
Fig. 3 - SiP12116 Functional Block Diagram
S17-0308-Rev. C, 06-Mar-17
5
Document Number: 62969
For technical questions, contact: [email protected]
THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT
ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
5 Page 
www.vishay.com
Inductor Selection
In order to determine the inductance, the ripple current must
first be defined. Cost, PCB size, output ripple, and efficiency
are all used in the selection process. Low inductor values
result in smaller size and allow faster transient performance
but create higher ripple current which can reduce efficiency.
Higher inductor values will reduce the ripple current, and
transient response. Efficiency especially at higher load
currents will also be compromised due to the higher DCR
(within a given case size).
The ripple current also sets the boundary for power-save
operation. The switching regulator will typically enter
power-save mode when the load current decreases to 1/2 of
the ripple current. For example, if ripple current is 1 A then
power-save operation will typically start at loads
approaching 0.5 A. Alternatively, if ripple current is set at
40 % of maximum load current, then power-save will start
for loads less than ~ 20 % of maximum current.
Setting the ripple current 20 % to 50 % of the maximum load
current provides an optimal trade-off of the areas mentioned
above.
This table provides a simple easy guide for setting up the
board. If excessive jitter is noticed then reducing the
inductor to the next standard value may be needed.
SiP12116 CONFIGURATION LOOK UP TABLE
VIN
VOUT
INDUCTOR RFB_TOP RFB_BOTTOM
(V) (V)
(μH)
()
()
12 1
1.5
4.53k
6.81k
12 3.3 3.3 4.53k 1k
12 5
3.3
4.53k
619R
5
1
1.5
4.53k
6.81k
5 3.3 1.5 4.53k 1k
The equation for determining inductance is shown next.
Example
In this example, the inductor ripple current is set equal to
30 % of the maximum load current. Thus ripple current will
be 30 % x 3 A or 0.9 A. To find the minimum inductance
needed, use the VIN and tON values that correspond to
VIN max..
L = (VIN - VOUT) x
tON
Δi
Plugging numbers into the above equation we get
SiP12116
Vishay Siliconix
A smaller value of 1.5 μH is selected which is a standard
value. This will increase the maximum ripple current by
25 %.
Note that the inductor must be rated for the maximum DC
load current plus 1/2 of the ripple current. The actual ripple
current using the chosen 1 μH inductor comes out to be.
151 ns
Δi = (13.2 V - 1.2 V) x
= 1.2 A
1.5 μH
Output Capacitance Calculation
The output capacitance is usually chosen to meet transient
requirements. A worst-case load release, from maximum
load to no load at the exact moment when inductor current
is at the peak, determines the required capacitance. If the
load release is instantaneous (load changes from maximum
to zero in < 1/fsw μs), the output capacitor must absorb all
the inductor's stored energy. This will approximately cause
a peak voltage on the capacitor according to the following
equation.
COUT min. =
L x (IOUT +
1
2
x IRIPPLE max.)2
(VPEAK)2 - (VOUT)2
Assuming a peak voltage VPEAK of 1.3 V (100 mV rise upon
load release), and a 3 A load release, the required
capacitance is shown by the next equation.
1.5 μH x (3 A + 0.5 x (1.2 A)2
COUT min. =
(1.3 V)2 - (1.2 V)2
= 77.8 μF
If the load release is relatively slow, the output capacitance
can be reduced.
Using MLCC ceramic capacitors we will use 3 x 22 μF or
66 μF as the total output capacitance.
Switching Frequency Variations
The switching frequency variation in COT can be mainly
attributed to the increase in conduction losses as the load
increases. Since the on time is constant the controller must
account for losses and maintain output regulation by
reducing the off time. Hence the fsw tends to increase with
load.
151 x 10-9 s
L = (13.2 V - 1.2 V) x
= 2 μH
0.9 A
S17-0308-Rev. C, 06-Mar-17
11
Document Number: 62969
For technical questions, contact: [email protected]
THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT
ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
11 Page | ||
| Páginas | Total 18 Páginas | |
| PDF Descargar | [ Datasheet SiP12116.PDF ] | |
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