RICOH R1203x Technical data
R1203x SERIES
STEP-UP DC/DC CONVERTER FOR WHITE LED BACK LIGHT
NO.EA-271-111123
OUTLINE
The R1203x Series are PWM control type step-up DC/DC converter ICs with low supply current.
The R1203x is fully dedicated to drive White LEDs with constant current. Each of these ICs consists of an NMOS FET, an oscillator, a PWM comparator, a voltage reference unit, an error amplifier, a current limit circuit, an under voltage lockout circuit (UVLO), and an over-voltage protection circuit (OVP).
The R1203x can drive white LEDs in constant current with high efficiency by using an inductor, a diode , a resistor and capacitors as external components.
The LEDs current can be set by an external resistance value and can adjust the dimming of LEDs by CE pin according to the signal of PWM. Feedback voltage is 0.2V, therefore power loss by current setting resistance is small and efficiency is good. Maximum duty cycle is internally fixed, Typ. 91%. LEDs can be driven from low voltage. Protection circuits are the current limit of Lx peak current, the over voltage limit of output, and the under voltage lockout function.
It is controllable the dimming of LEDs quickly when the PWM signal (between 200Hz to 300kHz) input to CE pin. If the CE pin input is "L" in the fixed time (Typ. 0.5ms), the IC becomes the standby mode and turns OFF LEDs.
FEATURES
• Supply Current ........................................................... |
Typ. 500μA |
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• Standby Current ......................................................... |
Max. 5μA |
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Input Voltage Range .................................................. |
1.8V to 5.5V |
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Feedback Voltage ...................................................... |
0.2V |
• Feedback Voltage Accuracy....................................... |
±1.0% (±10mV) |
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Temperature-Drift Coefficient of Feedback Voltage ... |
±150ppm/°C |
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Oscillator Frequency .................................................. |
Typ. 1.2MHz |
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Maximum Duty Cycle ................................................. |
Typ. 91% |
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Switch ON Resistance ............................................... |
Typ. 1.35Ω |
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UVLO Detector Threshold.......................................... |
Typ. 1.6V |
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Lx Current Limit Protection ........................................ |
Typ. 700mA |
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OVP Detector Threshold............................................ |
Typ. 29.5V |
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Switching Control ....................................................... |
PWM |
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LED dimming control.................................................. |
by external PWM signal (Frequency 200Hz to 300kHz) |
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Packages ................................................................... |
DFN1616-6B, SOT-23-6 |
• Ceramic capacitors are recommended...................... |
0.22μF |
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APPLICATION
• White LED Backlight for portable equipment
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R1203x
BLOCK DIAGRAMS
V |
V |
LX |
VOUT |
FB |
IN |
Err. Amp. |
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UVLO |
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PWM Comp. |
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+ |
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+ |
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– |
R |
Q |
Switch |
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– |
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vref |
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S |
Control |
OVP |
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PWM |
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Oscillator |
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Cntrl |
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Slope Com- |
Current |
Current |
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EN |
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pensation |
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Protect |
sense |
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Shutdown |
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Σ |
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delay |
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CE |
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CE |
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GND |
SELECTION GUIDE
The package for the ICs can be selected at the user's request. |
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Product Name |
Package |
Quantity per Reel |
Pb Free |
Halogen Free |
R1203L071B-TR |
DFN1616-6B |
5,000 pcs |
Yes |
Yes |
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R1203N071B-TR-FE |
SOT-23-6 |
3,000 pcs |
Yes |
Yes |
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R1203x
PIN CONFIGURATIONS
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• DFN1616-6B |
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Top View |
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Bottom View |
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• SOT-23-6
6 5 4
(mark side)
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PIN DESCRIPTIONS
• DFN1616-6B
Pin No |
Symbol |
Pin Description |
1 |
CE |
Chip Enable Pin ("H" Active) |
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2 |
VFB |
Feedback Pin |
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3 |
Lx |
Switching Pin (Open Drain Output) |
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4 |
GND |
Ground Pin |
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5 |
VIN |
Input Pin |
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6 |
VOUT |
Output Pin |
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) Tab is GND level. (They are connected to the reverse side of this IC.)
The tab is better to be connected to the GND, but leaving it open is also acceptable.
• SOT-23-6
Pin No |
Symbol |
Pin Description |
1 |
CE |
Chip Enable Pin ("H" Active) |
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2 |
VOUT |
Output Pin |
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3 |
VIN |
Input Pin |
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4 |
Lx |
Switching Pin (Open Drain Output) |
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5 |
GND |
Ground Pin |
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6 |
VFB |
Feedback Pin |
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R1203x
ABSOLUTE MAXIMUM RATINGS |
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(GND=0V) |
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Symbol |
Item |
Rating |
Unit |
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VIN |
VIN Pin Voltage |
−0.3 to 6.5 |
V |
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VCE |
CE Pin Voltage |
−0.3 to VIN+0.3 |
V |
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VFB |
VFB Pin Voltage |
−0.3 to VIN+0.3 |
V |
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VOUT |
VOUT Pin Voltage |
−0.3 to 32 |
V |
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VLX |
LX Pin Voltage |
−0.3 to 32 |
V |
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ILX |
LX Pin Current |
1000 |
mA |
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PD |
Power Dissipation (DFN1616-6B) |
640 |
mW |
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Power Dissipation (SOT-23-6) |
420 |
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Ta |
Operating Temperature Range |
−40 to 85 |
°C |
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Tstg |
Storage Temperature Range |
−55 to 125 |
°C |
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) For Power Dissipation, please refer to PACKAGE INFORMATION.
ABSOLUTE MAXIMUM RATINGS
Electronic and mechanical stress momentarily exceeded absolute maximum ratings may cause the permanent damages and may degrade the life time and safety for both device and system using the device in the field. The functional operation at or over these absolute maximum ratings is not assured.
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