|
|
PDF XR79103 Data sheet ( Hoja de datos )
| Número de pieza | XR79103 | |
| Descripción | 3A Synchronous Step-Down COT Power Module | |
| Fabricantes | Exar | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de XR79103 (archivo pdf) en la parte inferior de esta página. Total 19 Páginas | ||
|
No Preview Available !
XR79103
22V, 3A Synchronous Step-Down
COT Power Module
Description
The XR79103 is part of a family of 22V synchronous step-down
power modules combining the controller, drivers, inductor, passive
components and MOSFETs in a single package for point-of-load
supplies. This module requires very few external components leading
to ease of design and fast time to market. The XR79103 has load
current rating of 3A. A wide 4.5V to 22V input voltage range allows
for single supply operation from industry standard 5V, 12V and
19.6V rails.
With a proprietary emulated current mode Constant On-Time (COT)
control scheme, the XR79103 provides extremely fast line and load
transient response using ceramic output capacitors. It requires no
loop compensation, simplifying circuit implementation and reducing
overall component count. The control loop also provides 0.2% load
and 0.2% line regulation and maintains constant operating frequency.
A selectable power saving mode, allows the user to operate in
Discontinuous Current Mode (DCM) at light current loads, significantly
increasing the converter efficiency.
A host of protection features, including overcurrent, over temperature,
short-circuit and UVLO, helps achieve safe operation under abnormal
operating conditions.
The XR79103 is available in a RoHS-compliant, green/halogen-free
space-saving 6mm x 6mm x 4mm QFN package.
Typical Application
FEATURES
■■ 3A step-down power module
4.5V to 22V wide single input voltage
≥0.6V adjustable output voltage
■■ Controller, drivers, inductor, passive
components and MOSFETs integrated in
one package
■■ Proprietary constant on-time control
No loop compensation required
Stable with ceramic output capacitors
Programmable 100ns to 1µs on-time
Constant 600kHz to 800kHz frequency
Selectable CCM or DCM/CCM
operation
■■ Precision enable and power-good flag
■■ Programmable soft-start
■■ 6mm x 6mm x 4mm QFN package
APPLICATIONS
■■ FPGA, DSP and processor supplies
■■ Distributed power architecture
■■ Point-of-load converters
■■ Power supply modules
■■ Base stations
■■ Switches and routers
■■ Servers
VIN
ENABLE/MODE
POWER GOOD
CIN RPGOOD
CVCC CSS
RON
VIN PVIN
EN/MODE
PGOOD
VOUT
VCC XR79103
SW
SS ILIM
TON
AGND
PGND
FB
RLIM
Figure 1. Typical Application
VOUT
RFB1
RFB2
COUT
100
95 800kHz
90
85
80
75 600kHz
3.3V
70 2.5V
1.8V
65
1.5V
1.2V
1.0V
60
0.0 0.5 1.0 1.5 2.0 2.5 3.0
IOUT (A)
Figure 2. Efficiency, 12VIN
REV1B
1/19
1 page  
Pin Configuration
XR79103
SS 1
PGOOD 2
FB 3
AGND 4
VIN 5
VCC 6
PGND 7
SW 8
PGND 9
PGND 10
AAGGND
PPAADD
SW
PAD
PVIN PAD
SW
PAD
VOUT
PAD
31 PVIN
30 PGND
29 PGND
28 SW
27 SW
26 SW
25 SW
24 VOUT
23 VOUT
22 VOUT
Pin Functions
Pin Number
1
2
3
4, 40,
AGND Pad
5
6
7
9-14, 29, 30
8, 15, 25-28,
SW Pads
16-24,
VOUT Pad
31-37,
PVIN Pad
38, BST Pad
39
41
42
Pin Name
SS
PGOOD
FB
AGND
VIN
VCC
PGND
PGND
SW
VOUT
PVIN
BST
ILIM
EN/MODE
TON
Type Description
A
OD, O
A
Soft-start pin. Connect an external capacitor between SS and AGND to program the soft-start rate based
on the 10μA internal source current.
Power-good output. This open-drain output is pulled low when VOUT is outside the regulation.
Feedback input to feedback comparator. Connect with a set of resistors to VOUT and AGND in order to
program VOUT.
A Analog ground. Control circuitry of the IC is referenced to this pin. Connect to PGND.
PWR
PWR
PWR
PWR
PWR
IC supply input. Provides power to internal LDO. Connect to PVIN pins.
The output of LDO. Bypass with a 4.7μF capacitor to AGND.
Controller low-side driver ground. Connect with a short trace to closest PGND pins or PGND pad.
Ground of the power stage. Should be connected to the system’s power ground plane.
Switching node. It internally connects the source of the high-side FET, the drain of the low-side FET,
the inductor and bootstrap capacitor. Pins 8 and 15 maybe left floating. Use thermal vias and/or sufficient
PCB land area in order to heatsink the low-side FET and the inductor.
PWR Output of the power stage. Place the output filter capacitors as close as possible to these pins.
PWR Power stage input voltage. Place the input filter capacitors as close as possible to these pins.
A
Controller high-side driver supply pin. It is internally connected to SW via a 0.1μF bootstrap capacitor.
Leave this pin floating.
A Overcurrent protection programming. Connect with a short trace to SW pins.
I
Precision enable pin. Pulling this pin above 1.9V will turn the IC on and it will operate in forced CCM. If the
voltage is raised above 3.0V, then the IC will operate in DCM or CCM depending on load.
A Constant on-time programming pin. Connect with a resistor to AGND.
NOTE:
A = Analog, I = Input, O = Output, OD = Open Drain, PWR = Power.
REV1B
5/19
5 Page 
XR79103
Applications Information
Functional Description
The XR79103 is a synchronous step-down proprietary
emulated current-mode Constant On-Time (COT) module.
The on-time, which is programmed via RON, is inversely
proportional to VIN and maintains a nearly constant
frequency. The emulated current-mode control is stable
with ceramic output capacitors.
Each switching cycle begins with GH signal turning on
the high-side (switching) FET for a pre-programmed time.
At the end of the on-time, the high-side FET is turned off and
the low-side (synchronous) FET is turned on for a preset
minimum time (250ns nominal). This parameter is termed
minimum off-time. After the minimum off-time, the voltage at
the feedback pin FB is compared to an internal voltage ramp
at the feedback comparator. When VFB drops below the
ramp voltage, the high-side FET is turned on and the cycle
repeats. This voltage ramp constitutes an emulated current
ramp and makes possible the use of ceramic capacitors,
in addition to other capacitor types, for output filtering.
Enable/Mode Input (EN/MODE)
The EN/MODE pin accepts a tri-level signal that is used
to control turn on/off. It also selects between two modes
of operation: forced CCM and DCM/CCM. If EN is pulled
below 1.8V, the module shuts down. A voltage between
2.0V and 2.8V selects the forced CCM mode which will run
the module in continuous conduction at all times. A voltage
higher than 3.1V selects the DCM/CCM mode which will run
the module in discontinuous conduction at light loads.
Selecting the Forced CCM Mode
In order to set the module to operate in forced CCM, a voltage
between 2.0V and 2.8V must be applied to EN/MODE. This
can be achieved with an external control signal that meets
the above voltage requirement. Where an external control is
not available, the EN/MODE can be derived from VIN. If VIN
is well regulated, use a resistor divider and set the voltage
to 2.5V. If VIN varies over a wide range, the circuit shown
in Figure 25 can be used to generate the required voltage.
Note that at VIN of 4.5V and 22V the nominal Zener voltage
is 3.8V and 4.7V respectively. Therefore for VIN in the range
of 4.5V to 22V, the circuit shown in Figure 25 will generate
VEN required for forced CCM.
Selecting the DCM/CCM Mode
In order to set the module operation to DCM/CCM, a voltage
between 3.1V and 5.5V must be applied to EN/MODE pin.
If an external control signal is available, it can be directly
connected to EN/MODE. In applications where an external
control is not available, EN/MODE input can be derived
from VIN. If VIN is well regulated, use a resistor divider and
set the voltage to 4V. If VIN varies over a wide range, the
circuit shown in Figure 26 can be used to generate the
required voltage for DCM/CCM operation.
VIN
RZ
10k
Zener
MMSZ4685T1G or
Equivalent
R1
24.3k, 1%
R2 EN/MODE
35.7k, 1%
Forced CCM, wide VIN range
Figure 25. Selecting Forced CCM by
Deriving EN/MODE from VIN
VIN
Zener
MMSZ4685T1G or
Equivalent
RZ
10k
VEN
EN/MODE
DCM/CCM, wide VIN range
Figure 26. Selecting DCM/CCM by
Deriving EN/MODE from VIN
REV1B
11/19
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet XR79103.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| XR79103 | 3A Synchronous Step-Down COT Power Module | Exar |
| XR79106 | 6A Synchronous Step-Down COT Power Module | Exar |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |