R1224N SERIES
PWM/VFM step-down DC/DC Controller
NO.EA-096-160524
OUTLINE
The R1224N Series are CMOS-based PWM step-down DC/DC Converter controllers with low supply current.
Each of these ICs consists of an oscillator, a PWM control circuit, a reference voltage unit, an error amplifier, a
phase compensation circuit, a soft-start circuit, a protection circuit, a PWM/VFM alternative circuit, a chip enable
circuit, resistors for output voltage detect, and input voltage detect circuit. A low ripple, high efficiency step-down
DC/DC converter can be easily composed of this IC with only several external components, or a power-transistor,
an inductor, a diode and capacitors. Output Voltage is fixed or can be adjusted with external resistors (Adjustable
types are without PWM/VFM alternative circuit).
With a PWM/VFM alternative circuit, when the load current is small, the operation is automatically switching
into the VFM oscillator from PWM oscillator. Therefore, the efficiency at small load current is improved. Several
types of the R1224Nxxx, which are without a PWM/VFM alternative circuit, are also available.
If the term of maximum duty cycle keeps on a certain time, the embedded protection circuit works. The
protection circuit is Reset-type protection circuit, and it works to restart the operation with soft-start and repeat
this operation until maximum duty cycle condition is released. When the cause of large load current or something
else is removed, the operation is automatically released and returns to normal operation. Further, built-in UVLO
function works when the input voltage is equal or less than UVLO threshold, it makes this IC be standby and
suppresses the consumption current and avoid an unstable operation.
FEATURES
Supply Current ................................................................ Typ. 20A (R1224Nxx2E/F/M/L, R1224N102M)
Typ. 30A (R1224Nxx2G, R1224N102G)
Typ. 40A (R1224Nxx2H, R1224N102H)
Standby Current .............................................................. Typ. 0A
Input Voltage Range ....................................................... 2.3V to 18.5V
Output Voltage Range ..................................................... 1.2V to 6.0V (0.1V steps; R1224Nxx2x)
1.0V to V
IN
(R1224N102x)
Output Voltage Accuracy.................................................
2.0%
Oscillator Frequency ....................................................... Typ. 180kHz (R1224Nxx2L/M, R1224N102M)
Typ. 300kHz (R1224Nxx2E/G, R1224N102G)
Typ. 500kHz (R1224Nxx2F/H, R1224N102H)
Efficiency ......................................................................... Typ. 90%
Low Temperature-Drift Coefficient of Output Voltage...... Typ.
100ppm/°C
Package .......................................................................... SOT-23-5
Built-in Soft-start Function ............................................... Typ. 10ms
Built-in Current Limit Circuit
APPLICATIONS
Power source for hand-held communication equipment, cameras, video instruments such as VCRs,
camcorders.
Power source for battery-powered equipment.
Power source for household electrical appliances.
1
R1224N
BLOCK DIAGRAM
Fixed Output Voltage Type
V
IN
5
OSC
3
V
OUT
EXT
4
PWM/VFM
CONTROL
Amp
Vref
Soft Start
Protection
UVLO
Chip Enable
Vref
1
CE
2
GND
Adjustable Output Voltage Type
V
IN
5
OSC
3
V
FB
EXT
4
Amp
Vref
Soft Start
Protection
UVLO
Chip Enable
Vref
1
CE
2
GND
2
R1224N
SELECTION GUIDE
The output voltage, the oscillator frequency, the modulation method and the output voltage adjustment for the
ICs can be selected at the user’s request.
Product Name
R1224Nxx2-TR-FE
Package
SOT-23-5
Quantity per Reel
3,000 pcs
Pb Free
Yes
Halogen Free
Yes
xx : The output voltage can be designated in the range from 1.2V(12) to 6.0V(60) in 0.1V steps.
(For externally adjustable output voltage type, feedback voltage of 1.0V(10).)
: The oscillator frequency, the modulation method and the output voltage adjustment are options as follows.
Code
E
F
G
H
L
M
Oscillator frequency
300kHz
500kHz
300kHz
500kHz
180kHz
180kHz
PWM/VFM
alternative circuit
Yes
Yes
No
No
Yes
No
Output voltage
adjustment
No
No
Yes
Yes
No
Yes
PIN CONFIGURATION
SOT-23-5
5
4
(mark side)
1
2
3
PIN DESCRIPTION
Pin No
1
2
3
4
5
Symbol
CE
GND
V
OUT
(V
FB
)
EXT
V
IN
Ground Pin
Pin Description
Chip Enable Pin ("H" Active)
Pin for Monitoring Output Voltage (Feedback Voltage)
External Transistor Drive Pin (CMOS Output)
Power Supply Pin
3
R1224N
ABSOLUTE MAXIMUM RATINGS
Symbol
V
IN
V
EXT
V
CE
V
OUT
/V
FB
I
EXT
P
D
T
opt
T
stg
GND=0V
Item
V
IN
Supply Voltage
EXT Pin Output Voltage
CE Pin Input Voltage
V
OUT
/V
FB
Pin Input Voltage
EXT Pin Inductor Drive Output Current
Power Dissipation (SOT-23-5)
Operating Temperature Range
Storage Temperature Range
Rating
0.3
to 20
0.3
to V
IN
0.3
0.3
to V
IN
0.3
0.3
to V
IN
0.3
50
420
40
to 85
55
to 125
Unit
V
V
V
V
mA
mW
C
C
)
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.
4
R1224N
ELECTRICAL CHARACTERISTICS
R1224Nxx2x (x=E/F/G/H/L/M) except R1224N102x
Item
Operating Input Voltage
Step-down Output Voltage
Step-down Output Voltage
Temperature Coefficient
V
IN
½V
CE
½V
SET
1.5V,
I
OUT
½100mA
When V
SET
≤1.5V,
V
IN
½V
CE
½3.0V
40°C≤T
opt
≤85°C
V
IN
½V
CE
½V
SET
1.5V,
I
OUT
½100mA
L/M Version
E/G Version
F/H Version
40°C≤T
opt
≤85°C
V
IN
½V
CE
½V
OUT
½18.5V
E/F/L/M Version
G version
H version
V
IN
½18.5V,
V
CE
½0V,
V
OUT
½0V
V
IN
½8V,
V
EXT
½7.9V,
V
OUT
½8V,
V
CE
½8V
V
IN
½8V,
V
EXT
½0.1V,
V
OUT
½0V,
V
CE
½8V
V
IN
½V
CE
½V
OUT
½18.5V
V
IN
½V
OUT
½18.5V,
V
CE
½0V
V
IN
½8V,
I
OUT
½10mA
V
IN
½8V,
I
OUT
½10mA
100
E/F/L Version
V
IN
½V
CE
½2.5V
to 1.5V, V
OUT
½0V
V
IN
½V
CE
½1.5V
to 2.5V, V
OUT
½0V
V
IN
½V
SET
1.5V,
I
OUT
½10mA
V
CE
½0VV
SET
1.5V
V
IN
½V
CE
½V
SET
1.5V
V
OUT
½V
SET
1.5V0V
5
5
1.8
35
2.0
V
UVLO1
0.1
10
15
2.2
2.3
20
30
0.5
1.5
0.3
20
Conditions
Min.
2.3
V
SET
0.98
V
SET
100
Typ.
V
IN
V
OUT
V
OUT
/
T
opt
Topt=25C
Symbol
Max.
18.5
V
SET
1.02
Unit
V
V
ppm/°C
f
osc
Oscillator Frequency
144
240
400
180
300
500
0.2
20
30
40
0
17
30
0
0
216
360
600
kHz
f
osc
/
T
opt
Oscillator Frequency
Temperature Coefficient
Supply Current 1
Standby Current
EXT "H" Output Current
EXT "L" Output Current
CE "H" Input Current
CE "L" Input Current
CE "H" Input Voltage
CE "L" Input Voltage
Oscillator Maximum
Duty Cycle
VFM Duty Cycle
UVLO Voltage
UVLO Release Voltage
Delay Time by Soft-Start function
Delay Time for protection circuit
%/°C
50
60
80
0.5
10
I
DD1
I
standby
I
EXTH
I
EXTL
I
CEH
I
CEL
V
CEH
V
CEL
Maxduty
VFMdty
V
UVLO1
V
UVLO2
t
start
t
prot
A
A
mA
mA
0.5
A
A
V
V
%
%
V
V
ms
ms
RECOMMENDED OPERATING CONDITIONS (ELECTRICAL CHARACTERISTICS)
All of electronic equipment should be designed that the mounted semiconductor devices operate within the
recommended operating conditions. The semiconductor devices cannot operate normally over the
recommended operating conditions, even if when they are used over such conditions by momentary
electronic noise or surge. And the semiconductor devices may receive serious damage when they continue
to operate over the recommended operating conditions.
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