Features: * Standby Current.................................. TYP. 0A (for B/D version)
* Input Voltage Range.............................. 2.5V to 6.0V
* Built-in Latch-type Protection Function (Output Delay Time can be set with an external capacitor)
* Two Options of Basic Oscillator Frequency.... 300kHz, 700kHz
* Max Duty Cycle.................................... Typ. 90%
* High Reference Voltage Accuracy.............. ±1.5%
* U.V.L.O. Threshold level.......................... Typ. 2.2V (Hysteresis TYP. 0.13V)
* Small Package.......... SOT-23-6W or thin (package height MAX. 0.85mm) SON-6 (Under Development)Application* Constant Voltage Power Source for portable equipment.
* Constant Voltage Power Source for LCD and CCD.Pinout
Specifications
|
Symbol |
Item |
Rating |
Unit |
|
VIN |
VIN Pin Voltage |
6.5 |
V |
|
VEXT |
EXT Pin Output Voltage |
-0.3∼VIN+0.3 |
V |
|
VDLY |
DELAY Pin Voltage |
-0.3∼VIN+0.3 |
V |
|
VAMP |
AMPOUT Pin Voltage |
-0.3∼VIN+0.3 |
V |
|
VCE |
CE Pin Input Voltage |
-0.3∼VIN+0.3 |
V |
|
VFB |
VFB Pin Voltage |
-0.3∼VIN+0.3 |
V |
|
IAMP |
AMPOUT Pin Current |
±10 |
mA |
|
IEXT |
EXT Pin Inductor Drive Output Current |
±50 |
mA |
|
PD |
Power Dissipation |
250 |
mW |
|
Topt |
Operating Temperature Range |
-40∼+85 |
|
|
Tstg |
Storage Temperature Range |
-55∼+125 |
|
DescriptionThe R1211DX Series are CMOS-based PWM step-up DC/DC converter controllers with low supply current.Each of the R1211DX Series consists of an oscillator, a PWM control circuit, a reference voltage unit, an error amplifier, a reference current unit, a protection circuit, and an under voltage lockout (UVLO) circuit. A low ripple, high efficiency step-up DC/DC converter can be composed of this IC with some external components, or an inductor, a diode, a power MOSFET, divider resisters, and capacitors.
Phase compensation has been made internally in the R1211X002B/R1211DX Series, while phase compensation can be made externally as for R1211X002A/C Series. B/R1211DX version has stand-by mode. Max duty cycle is internally fixed typically at 90%. Soft start function is built-in, and Soft-starting time is set typically at 9ms(A/B, 700kHz version) or 10.5ms(C/R1211DX, 300kHz version). As for the protection circuit, after the soft-starting time, if the maximum duty cycle is continued for a certain period, the R1211DX Series latch the external driver with its off state, or Latch-type protection circuit works. The delay time for latch the state can be set with an external capacitor.
To release the protection circuit, restart with power-on (Voltage supplier is equal or less than UVLO detector threshold level), or once after making the R1211DXbe stand-by with chip enable pin and enable the circuit again.
R1211DX Data Sheet
