R1224N Series
PWM/VFM Step-down DC/DC Controller with Ext. Tr.
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 type protection circuit embedded into the device limits
output current by repeatedly triggering the soft start circuit when the oscillator maximum duty cycle continues for a predetermined
period of time. When the oscillator maximum duty cycle ends, normal operation is resumed automatically. R1224N also includes an
under-voltage lockout circuit (UVLO) that stops DC/DC operation and prevents malfunction when the supply voltage falls below the
UVLO detect voltage and reduces supply current.
FEATURES
•
Supply Current (I
DD1
)·················· Typ. 20μA (E, F, L, M Versions), Typ. 30μA (G Version),
•
•
•
Typ. 40μA (H Version) (V
IN
=V
OUT
=18.5V)
Standby Current (I
standby
) ············ Max. 0.5μA (In standby)
Input Voltage Range (V
IN
) ·········· 2.3V to 18.5V
Output Voltage Range (V
OUT
)····· 1.2V to 6.0V (internally fixed R1224Nxx2E/F/L)
Externally adjustable (Feedback voltage of 1.0V, R1224Nxx2G/H/M)
•
Output Voltage Accuracy ················
±
2%
•
Oscillator Frequency (f
osc
) ·············· 180kHz, 300kHz, 500kHz
•
Oscillator Maximum Duty Cycle (Maxduty) ··· Min. 100%
•
UVLO Detect Voltage (V
UVLO
) ········· Typ. 2.0V
•
Soft Start Time (t
start
) ······················· Typ. 10ms
•
Reset Protection Circuit ················· Delay time for protection
•
Typ. 15ms
Package ········································· SOT-23-5
BLOCK DIAGRAMS
R1224Nxx2E/F/L
(Internally fixed output voltage type)
OSC
5
3
R1224Nxx2G/H/M
(Externally adjustable output voltage type)
OSC
5
3
V
IN
V
OUT
V
IN
V
FB
EXT
4
-
+
PWM/VFM
CONTROL
-
Amp
+
EXT
Vref
Soft Start
4
-
+
-
Amp
+
Vref
Soft Start
Protection
UVLO
Chip Enable
+
-
Vref
1
CE
Protection
UVLO
Chip Enable
+
-
Vref
1
CE
2
2
GND
GND
SELECTION GUIDE
Package
SOT-23-5
Quantity per Reel
Part No.
3,000 pcs
R1224N.xx.2.
∗
-TR-F
TYPICAL APPLICATIONS
R1224Nxx2E/F/L
L
PMOS
+
- C1
PMOS
4
5
R1224Nxx2G/H/M
L
R4
C4
R3
+
-
C3
.xx.
: Specify the output voltage within the range
1.2V (.12.) to 6.0V (.60.) in 0.1V steps.
(For externally adjustable output voltage type, feedback voltage of 1.0V(.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.:
180kHz, fixed PWM, adjustable output voltage
C1
R1
5
1
4
V
IN
CE
EXT
GND
2
V
OUT 3
SD
+
-
C3
LOAD
R1
1
V
IN
CE
EXT
GND
2
V
FB
3
C2
C2
CE CONTROL
CE CONTROL
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 : 47μF, C4 : 1000pF, R1 : 10Ω, R3 : 2.7kΩ,
Output voltage at 2.5V⋅⋅⋅R2 : 22kΩ, R4 : 33kΩ
PACKAGE (Top View)
SOT-23-5
5
4
TYPICAL CHARACTERISTIC
R1224N332E
100
90
80
Efficiency vs. Output Current
V
IN
=7V, L=CDRH127(10μH)
Efficiency
η
(%)
70
60
50
40
30
20
10
0
0.1
1
10
100
1000
Output Current I
OUT
(mA)
10000
1
2
3
1
2
3
4
5
CE
GND
V
OUT
or V
FB
EXT
V
IN
APPLICATIONS
•
Power source for hand-held communication equipment, cameras, and VCRs
•
Power source for home appliances
No.EK-101-091101
•
Power source for battery-powered equipment
Step-down DC/DC Converter
LOAD
SD
R2
1. The products and the product specifications described in this document are subject to change or
discontinuation of production without notice for reasons such as improvement. Therefore, before
deciding to use the products, please refer to Ricoh sales representatives for the latest
information thereon.
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without prior written consent of Ricoh.
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exporting or otherwise taking out of your country the products or the technical information
described herein.
4. The technical information described in this document shows typical characteristics of and
example application circuits for the products. The release of such information is not to be
construed as a warranty of or a grant of license under Ricoh's or any third party's intellectual
property rights or any other rights.
5. The products listed in this document are intended and designed for use as general electronic
components in standard applications (office equipment, telecommunication equipment,
measuring instruments, consumer electronic products, amusement equipment etc.). Those
customers intending to use a product in an application requiring extreme quality and reliability,
for example, in a highly specific application where the failure or misoperation of the product
could result in human injury or death (aircraft, spacevehicle, nuclear reactor control system,
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devices, life support system etc.) should first contact us.
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semiconductor products are likely to fail with certain probability. In order to prevent any injury to
persons or damages to property resulting from such failure, customers should be careful enough
to incorporate safety measures in their design, such as redundancy feature, firecontainment
feature and fail-safe feature. We do not assume any liability or responsibility for any loss or
damage arising from misuse or inappropriate use of the products.
7. Anti-radiation design is not implemented in the products described in this document.
8. Please contact Ricoh sales representatives should you have any questions or comments
concerning the products or the technical information.
RICOH COMPANY., LTD.
Electronic Devices Company
■Ricoh
presented with the Japan Management Quality Award for 1999.
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