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PDF SP7606 Data sheet ( Hoja de datos )
| Número de pieza | SP7606 | |
| Descripción | Wide Input Voltage Boost Controller | |
| Fabricantes | Sipex Corporation | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de SP7606 (archivo pdf) en la parte inferior de esta página. Total 17 Páginas | ||
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SP7606
Wide Input Voltage Boost Controller
FEATURES
• Fixed Frequency 1200kHz
Voltage-Mode PWM Operation
• Requires Tiny Inductors and Capacitors
www.DataSheet4U.com
• Adjustable Output Voltage up to 38V
• Up to 85% Efficiency
• Internal Compensation
• Built in current limit
• Low Supply Current
• 8-pin 2x3 DFN
PINOUT
DD 1
8
OC 2 SP7606 7
GND
GATE
3
4
2x3
8 Pin DFN
6
5
VCC
SHDN
VIN
FB
Now Available in Lead Free Packaging
APPLICATIONS
• White LED Backlighting when combined with SP7615 or SP7616
• Large LED arrays for general lighting
• General boost, flyback, or SEPIC converters
GENERAL DESCRIPTION
The SP7606 is a fixed frequency boost controller designed to drive loads up to 38V output
voltage. The SP7606 was developed to be used in conjunction with the SP7616 to drive a wide
range of led chains that require high anode voltages. The ability to disconnect the output
voltage feedback resistors (DD Pin) reduces shutdown current. The high switching frequency
allows the use of tiny external components and saves layout space and cost. The SP7606 is
available in a space-saving 8-pin 2x3 DFN.
TYPICAL APPLICATION SCHEMATIC
Boost converter 12V to 30V
ABSOLUTE MAXIMUM RATINGS
12/17/07 rev: A
SP7600
©Copyright 2007 Exar Corporation
EXAR RESERVES THE RIGHT TO MAKE CHANGES TO THIS DATASHEET. CALL FOR UPDATES: 1-510-668-7000
page 1 of 17
1 page  
SP7606
CIRCUIT DESCRIPTION THEORY OF OPERATION
The SP7606 converter is a voltage mode boost
controller. The control loop has built in Type 2
compensation coupled with high switching
frequency allows the user to use small
components when designing the output filter.
www.DataSheet4U.cTomhe equations below show generic
relationships as applicable to the boost
regulator running in discontinuous conduction
mode (DCM) and continuous conduction mode
(CCM) of operation.
The output voltage of the SP7606 can be set
by using an output voltage divider. The internal
reference of this part is set to 0.8V. Due to the
internal compensation, resistor R1 might need
to be chosen according to the desired gain of
the compensation loop. This resistor is
typically between 100K and 1M ohm. Resistor
R2 can be determined by:
Duty Cycle in continuous conduction mode
(CCM)
Where
Vd= Forward voltage drop of D1
Duty Cycle in discontinuous conduction mode
(DCM)
Vfb=800mV Feedback Voltage
R1=Top Voltage divider resistor
R2=Bottom Voltage divide resistor
200=the typical impedance of the DD
FET
For typical applications resistor R1 should be
connected between Vout and the DD pin. The
DD pin serves as a disconnect for the output
voltage divider when the SP7606 is disabled.
This feature allows the user to save power
when the converter is not running. The typical
Impedance of the DD FET when enabled is
200 ohms. If the DD pin is not used the resistor
R1 can be connected directly to the Vfb pin to
get the proper output voltage. If this type of
connection is used the Rdson of the DD Fet
can be ignored and the equation becomes:
Where fsw is the switching frequency
L is the inductor
Re is the effective resistance of the small
signal model
Re can be found by using as follows:
Setting the output voltage
Vfb=800mV Feedback Voltage
R1=Top Voltage divider resistor
R2=Bottom Voltage divide resistor
If the DD pin is not used the converter can be
used to boost voltages beyond 38V. A more
detailed discussion on this topic can be found
in the section “High Voltages Operation”. A 10
to 22pf decoupling capacitor from the feedback
pin to ground is recommended when the
SP7606 is used with resistor values above 20K
in the voltage divider circuit.
12/17/07 rev: A
SP7600
©Copyright 2007 Exar Corporation
EXAR RESERVES THE RIGHT TO MAKE CHANGES TO THIS DATASHEET. CALL FOR UPDATES: 1-510-668-7000
page 5 of 17
5 Page 
SP7606
Gain
www.DataSheet4U.com
0 dB
0 deg
Phase
-270 (deg)
Frequency
Gain of Control to Output transfer CCM
The compensation becomes much harder to
accomplish when due to the RHP zero as well
as the filter double pole. Unlike the DCM filter
the gain drops off sharply at the filter double
pole and does not recover. More over the
Right Half plane zero also adds another -90
degrees to the phase. Due to the RHP zero the
compensation network for a boost regulator
needs to roll off below the RHP zero location.
When compensating for CCM mode of
operation the user will need to add a phase
boost capacitor and resistor to help
compensate for the filter double pole. The
location of the zero and poles for Type 3
compensation is.
RZ CZ
CP
Comp
7
-5
+6
Vref
Vout
CZ1 RZ1
R1
Error Amplifier Type 3 Compensation
12/17/07 rev: A
SP7600
©Copyright 2007 Exar Corporation
EXAR RESERVES THE RIGHT TO MAKE CHANGES TO THIS DATASHEET. CALL FOR UPDATES: 1-510-668-7000
page 11 of 17
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet SP7606.PDF ] | |
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