R1224N Series
18.5V Input PWM/VFM Step-down DC/D C Controller with Ext. Tr.
No.EK-096-111001 Step-down DC/DC Converter
The R1224N
Series are low supply current CMOS-based PWM/VFM step-down DC/DC controller with an external output transistor.
By simply using a power transistor, an inductor , a diode, and a capacitor as external components, a high-efficiency step-down DC/DC
converter can be easily configured. The PWM/VFM alternative circuit automatically switches to VFM control in the smaller output
current range and provides high efficiency even in the smaller output current range. The version with fixed PWM control and
adjustable output voltage with an external resistor is also available. The reset t ype protection circuit em bed ded into t he device limits
output current b y repeatedly triggering the soft start circuit w hen the oscillator maximum duty cycle continues for a predetermined
period of time. When the oscillator maximum dut y cycle ends, normal operation is resume d automaticall y. R 1224N also includes a n
under-voltage lockout circuit (UVLO) that sto ps DC/DC operation and pre vents malfunction w hen the supply voltage falls below the
UVLO detect voltage and reduces supply current.
FEATURES
• Supply Current (IDD1)··················
Typ. 20
μ
A (E, F, L, M Versions), Typ. 30
μ
A (G Version),
Typ. 40
μ
A (H Version) (V
IN
=V
OUT=
18.5V)
• Standby Current (Istandby) ············Max. 0.5μA (In standby)
• Input Voltage Range (VIN)··········2.3V to 18.5V
• Output Voltage Range (VOUT)·····
1.2V to 6.0V (internally fixed R1224Nxx2E/F/L)
Externally adjustable (Feedback voltage : 1.0V, R1224Nxx2G/H/M)
• Output Voltage Accuracy················± 2%
• Oscillator Frequency (fosc) ··············
180kHz, 300kHz, 500kHz
•
Oscillator Max imum Du ty Cycle ( Maxduty )
···Min. 100%
• UVLO Detect Voltage (VUVLO)·········Typ. 2.0V
• Soft Start Time (tstart)·······················Typ. 10ms
• Reset Protection Circuit ·················
Delay time for protection
Typ. 15ms
• Package·········································SOT-23-5
BLOCK DIAGRAMS
R1224Nxx2E/F/L R1224Nxx2G/H/M
(Internally fixed output voltage type) (Externally adjustable output voltage type)
V
IN
V
OUT
CE
EXT
GND
PWM/VFM
CONTROL
+
-
+
-
Amp
OSC
Vref
Vref
Protection
Soft Start
Chip Enable
+
-
UVLO
5
4
2
1
3
V
IN 5
4
V
FB
CE
EXT
GND
+
-
+
-
Amp
OSC
Vref
Vref
Protection
Soft Start
Chip Enable
+
-
UVLO
2
1
3
SELECTION GUIDE TYPICAL APPLICATIONS
Halogen Free
Package
Q'ty per Reel
Part No.
SOT-23-5
3,000 pcs R1224N
.
xx
.
2
.
∗
-TR-FE R1224Nxx2E/F/L
VIN
CE
CE CONTROL
EXT
GND
VOUT C3
+
-
C2
C1
R1
PMOS
L
SD
LOAD
5
4
3
2
1
R1224Nxx2G/H/M
V
IN
CE
CE CONTROL
EXT
GND
V
FB
C3
+
-
C1
+
-
C2
C4R4
R2
R3
R1
PMOS
L
LOAD
SD
5
4
3
2
1
.
xx
.
:
Specify the output voltage within the range of
1.2V (
.
12
.
) to 6.0V (
.
60
.
) in 0.1V steps.
(For ex ternally adjustable ou tput voltage type, feedback voltage of 1.0 V(
.
10
.
))
.
∗
.
:
Specify the oscillator frequency, modulation method, output
voltage adjustment.
.
E
.
: 300kHz, PWM/VFM, fixed output voltage
.
F
.
: 500kHz, PWM/VFM, fixed output voltage
.
G
.
: 300kHz, fixed PWM, adjustable output voltage
.
H
.
: 500kHz, fixed PWM, adjustable output voltage
.
L
.
: 180kHz, PWM/VFM, fixed output voltage
.
M
.
: 180kH z , fixed PWM, adjustable output voltage
PMOS : HAT1044M, L : 27μH,
SD : RB063L-30, C1 : 10μF, C2 : 0.1μF,
C3 : 47μF, R1 : 10Ω
PMOS : HAT1044M, L : 27μH,
SD : RB063L-30, C1 : 10μF, C2 : 0.1μF,
C3 : 47
μ
F, C4 : 1000pF, R1 : 10
Ω
, R3 : 2.7k
Ω
,
Output voltage at
2.5V⋅⋅⋅R2 : 22kΩ, R4 : 33kΩ
PACKAGE (Top View) TYPICAL CHARACTERISTIC
SOT-23-5
1 3
5 4
2
1 CE
2 GND
3 VOUT or VFB
4 EXT
5 VIN
R1224N332E Efficiency vs. Output Current
V
IN
=7V, L=CDRH127(10μH)
0.1
30
40
100
90
0
70
80
50
60
10
20
1 10 100 1000 10000
Output Current I
OUT
(mA)
Efficiency
η (%)
APPLICATIONS
• Power source for hand-held communication equipment, cameras, and VCRs
• Power source for home appliances • Power source for battery-powered equipment
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.
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