R1202x Series
STEP-UP DC/DC CONVERTER with SHUTDOWN FUNCTION
NO.EA-255-170915
OUTLINE
The R1202x Series are CMOS-based PWM step-up DC/DC converter ICs with low supply current.
Each of these ICs consists of an NMOS FET, NPN transistor, an oscillator, a PWM comparator, a voltage
reference unit, an error amplifier, a current limit circuit, an under voltage lockout circuit (UVLO), an over-voltage
protection circuit (OVP), a soft-start circuit, a Maxduty limit circuit, and a thermal shutdown protection circuit. By
simply using an inductor, a resistor, and capacitors as external components, a high-efficiency step-up DC/DC
converter can be easily configured. At the standby mode, a rectifier transistor can separate the output from the
input.
The R1202x Series include a thermal shut-down circuit and an under-voltage lockout circuit (UVLO) which
separate the output from the input to shut down the current when the overheat caused when the output is connected
to the Gnd is detected and also during the UVLO detection. As other protection functions, the R1202x Series
contain a cycle by cycle current limit circuit that limits the Lx peak current, and an over-voltage protection circuit
(OVP) that detects the output overvoltage.
The R1202x Series offer three versions: the R1202xxxxA/B versions, which are optimized for constant-voltage
power supply and the R1202xxxxD version, which is optimized to drive serial white LEDs with constant current.
While the R1202xxxxA version discharges the V
OUT
output to 0V at the shutdown, the R1202xxxxB version doesn’t.
The brightness of the white LEDs can be adjusted quickly by applying a PWM signal (200Hz to 300kHz) to the CE
pin.
The R1202x Series are available in DFN1616-6B and TSOT-23-6 packages.
FEATURES
•
Input Voltage Range ......................................... 2.3V to 5.5V (R1202xxxxA/B)
1.8V to 5.5V (R1202xxxxD)
•
Supply Current ................................................. Typ. 800µA
•
Standby Current ............................................... Max. 5µA
•
Feedback Voltage ............................................ 1.0V±15mV (R1202xxxxA/B)
0.2V±10mV (R1202xxxxD)
•
Oscillator Frequency ........................................ Typ. 1.2MHz
•
Maximum Duty Cycle ....................................... Typ. 91%
•
UVLO Function ...............................................
Typ.2.0V (Hys.Typ.0.2V) (R1202xxxxA/B)
Typ.1.6V (Hys.Typ.0.1V) (R1202xxxxD)
•
Lx Current Limit Function ................................. Select from 350mA, 700mA
•
Over Voltage Protection ................................... Select from 14V-23V (Refer the Selection Guide)
•
LED dimming control for R1202xxxxD ............. by external PWM signal (Frequency 200Hz to 300kHz)
•
Thermal Protection Function .......................... Typ.150ºC(Hys.Typ.50ºC)
•
Built-in Auto Discharge Function ...................... R1202xxxxA
•
NMOS ON Resistance ..................................... 1.35Ω
•
Packages ......................................................... DFN1616-6B, TSOT-23-6
APPLICATION
•
Constant Voltage Power Source for portable equipment
•
OLED power supply for portable equipment
•
White LED Backlight for portable equipment
1
R1202x
NO.EA-255-170915
SELECTION GUIDE
The OVP threshold voltage, current limit, package and V
FB
/Auto discharge are user-selectable options.
Product Name
R1202Lyz1∗-TR
R1202Nyz3∗-TR-FE
y
Package
DFN1616-6B
TSOT-23-6
Quantity per Reel
5,000 pcs
3,000 pcs
Pb Free
Yes
Yes
Halogen Free
Yes
Yes
: Designation of OVP threshold
(3) 14V : R1202xxxxA/B/D
(4) 17V : R1202xxxxA/B
(5) 19V : R1202xxxxA/B
(6) 21V : R1202xxxxA/B
(7) 23V : R1202xxxxA/B/D
: Designation of current limit
(1) 350mA
(2) 700mA
: Designation of VFB, auto discharge function
VFB
1.0V
1.0V
0.2V
Auto discharge
○
×
×
z
∗
A
B
D
Auto-discharge function quickly lowers the output voltage to 0V, when the chip enable signal is switched from the active mode
to the standby mode, by releasing the electrical charge accumulated in the external capacitor.
2
京公网安备 11010802033920号
EEWORLD
