Boost Converter. RT8580 Datasheet

RT8580 Converter. Datasheet pdf. Equivalent

RT8580 Datasheet
Recommendation RT8580 Datasheet
Part RT8580
Description 36V DC/DC Boost Converter
Feature RT8580; ® RT8580 36V DC/DC Boost Converter General Description The RT8580 is a high performance, low noise.
Manufacture Richtek
Datasheet
Download RT8580 Datasheet




Richtek RT8580
®
RT8580
36V DC/DC Boost Converter
General Description
The RT8580 is a high performance, low noise, DC/DC Boost
Converter with an integrated 0.5A, 1Ω internal switch. The
RT8580's input voltage ranges from 3V to 5.5V, and it can
support the output voltage up to 40V. When used in optical
receiver applications requiring 80V to drive the APD
(Avalanche Photo Diode), the output voltage of RT8580
can be doubled up by a typical voltage doubler circuit.
The RT8580 adapts fixed frequency, current mode PWM
control loop to regulate the output voltage with fast transient
response and cycle-by-cycle current limit protection. The
protection features of RT8580 include : 1) input under-
voltage lockout, 2) output over-voltage protection, and 3)
over-temperature protection. The soft-start function and
PWM loop compensation is built-in internally to save
external soft-start capacitor and PWM loop compensation
components. By operating at 500kHz switching frequency,
the RT8580 system board can be made compact to achieve
low system BOM cost. The RT8580 is available in the
tiny package type SOT-23-6.
Marking Information
0E=DNN
0E= : Product Code
DNN : Date Code
Features
z Input Operating Range : 3V to 5.5V
z Wide Output Range : VCC to 40V
z Internal Power N-MOSFET Switch
z 500kHz Fixed Switching Frequency
z Minimize the External Component Counts
z Internal Soft-Start
z Internal Compensation
z Under-Voltage Lockout Protection
z Over-Temperature Protection
z RoHS Compliant and Halogen Free
Applications
z Cellular Phones
z Digital Cameras
z Portable Instruments
z Avalanche Photodiode Biasing
Ordering Information
RT8580
Package Type
E : SOT-23-6
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
` RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
` Suitable for use in SnPb or Pb-free soldering processes.
Simplified Application Circuit
VIN
C1
L1
RT8580
VCC
LX
SHDN
GND
PGND
FB
D1
R1
R2
VOUT
C2
Copyright ©2013 Richtek Technology Corporation. All rights reserved.
DS8580-00 August 2013
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1



Richtek RT8580
RT8580
Pin Configurations
(TOP VIEW)
LX VCC SHDN
654
23
PGND GND FB
SOT-23-6
Functional Pin Description
Pin No.
1
2
3
4
5
6
Pin Name
PGND
GND
FB
SHDN
VCC
LX
Pin Function
Power Ground.
Ground.
Feedback Voltage Input. Connect a resistor to GND to setting the current.
Shutdown Control Input. Apply a logic-low voltage to SHDN to shut down the
device. Connect SHDN to VIN for normal operation. Ensure that SHDN is not
greater than the input voltage, VCC.
Supply Voltage Input.
Switch Node.
Function Block Diagram
VCC
GND
LX
UVLO
Internal
Compensation
Internal
Soft-Start
OTP
PWM
+
Logic Control,
Minimum On
Time
OCP
Current-
Sense
Driver
EA
GM Slope
Compensation Shutdown
PWM
LPF
Enable
Logic
20ms
Oscillator
VREF
Reference
Voltage
1µA Bias
Current
PGND
FB SHDN
Copyright ©2013 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS8580-00 August 2013



Richtek RT8580
Operation
The RT8580 is a constant frequency, current mode Boost
regulator. In normal operation, the N-MOSFET is turned
on when the PWM control circuit is set by the oscillator.
As the N-MOSFET is on, the inductor current ramps up.
The N-MOSFET will be turned off when the inductor current
hits the level set by the PWM control loop. After the
N-MOSFET is turned off, the inductor current will ramp
down through the external catch diode until the OSC sets
high for the next switching cycle and the next cycle
repeats.
The operation of the RT8580 can be better understood by
referring to the block diagram. The voltage at the output of
the error amplifier is an amplified version of the difference
between the 1.25V reference voltage and the output
feedback voltage. If the feedback voltage drops below
(above) 1.25V, the output of the error amplifier increases
(decreases). This results in higher (lower) PWM turn on
duty and thus higher (lower) inductor peak current flowing
through the power FET. By this control loop operation,
the increased (decreased) power will be delivered to the
output to bring up (down) the output feedback voltage back
to 1.25V.
RT8580
When the RT8580 is enabled by SHDN pin, the internal
VREF ramps up to the target voltage in a specific time
period. There is also a built-in soft-start function. Both
ensure that the output voltage rises slowly to reduce the
input inrush current.
The protection features of RT8580 include : 1) input under-
voltage lockout, 2) output over-voltage protection, and 3)
over-temperature protection. When the input voltage is
lower than the UVLO threshold, the RT8580 will be turned
off. There is a 100mV hysteresis for the UVLO control.
When the junction temperature exceeds 150°C, the over-
temperature protection function will shut down the
switching operation. Once the junction temperature cools
down by approximately 25°C, the converter will
automatically resume switching.
Copyright ©2013 Richtek Technology Corporation. All rights reserved.
DS8580-00 August 2013
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3







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