R1225N Series
18.5V Input PWM/VFM Step-down DC/DC Controller with Ext. Tr.
The R1225N Series are low supply current CMOS-based PWM/VFM controlled step-down DC/DC controllers 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 is also available.
The latch type protection circuit embedded into the device latches the power MOS in the "OFF" state when the oscillator maximum duty
cycle continues for a predetermined period of time. Protection time is adjustable by the capacity of an external capacitor of the DLY pin.
R1225N also includes an under-voltage lockout circuit (UVLO) that stops DC/DC operation and prevents malfunction when the supply
voltage falls below the UVLO detector threshold and reduces supply current.
FEATURES
•
Supply Current (I
DD1
)······················· Typ. 20μA (A, B, J, K Versions),
•
•
•
•
Typ. 30μA (C Version),
Typ. 40μA (D Version) (No switching)
Standby Current (I
standby
) ················· Max. 0.5μA (CE="L")
Input Voltage Range (V
IN
) ··············· 2.3V to 18.5V
Output Voltage Range (V
OUT
)·········· 1.2V to 6.0V (Internally fixed)
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
•
Latch Type Protection Circuit··········Delay time for protection
•
Package··········································SOT-23-6W
Typ. 20ms
BLOCK DIAGRAM
R1225Nxx2x
V
IN
OSC
2
Start
func
6
V
OUT
EXT
1
-
+
PWM/VFM
CONTROL
-
Amp
+
Vref
Soft Start
Protection
DLY
3
Chip Enable
+
-
Vref
4
CE
UVLO
5
GND
SELECTION GUIDE
Halogen Free
Package
SOT-23-6W
Q'ty per Reel
Part No.
3,000 pcs R1225N.xx.2.
∗
-TR-FE
TYPICAL APPLICATION
R1225Nxx2x
L
PMOS
R1
C1
2
4
1
.xx.
: Specify the output voltage within the range of
1.2V (.12.) to 6.0V (.60.) in 0.1V steps.
.
∗
.
: Specify the oscillator frequency, modulation method.
.A.
: 300kHz, PWM/VFM,
.B.
: 500kHz, PWM/VFM,
.C.
: 300kHz, fixed PWM,
.D.
: 500kHz, fixed PWM,
.J.
: 180kHz, PWM/VFM,
.K.
: 180kHz, fixed PWM
V
IN
EXT V
OUT
CE GND DLY
5
6
3
C2
C4
CE CONTROL
PMOS : HAT1044M, L : 27μH, SD : RB063L-30,
C1 : 10μF, C2 : 0.1μF, C3 : 47μF, C4 : 0.02μF, R1 : 10Ω
PACKAGE (Top View)
SOT-23-6W
6
5
4
TYPICAL CHARACTERISTIC
R1225N332A Efficiency vs. Output Current
100
90
80
Efficiency
η
(%)
V
IN
=7V, L=CDRH127(10μH)
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
EXT
V
IN
DLY
4
5
6
CE
GND
V
OUT
APPLICATIONS
•
Power source for hand-held communication equipment, cameras, and VCRs
•
Power source for home appliances
No.EK-097-121001
•
Power source for battery-powered equipment
Step-down DC/DC Converter
LOAD
+
SD -
C3
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.
2. The materials in this document may not be copied or otherwise reproduced in whole or in part
without prior written consent of Ricoh.
3. Please be sure to take any necessary formalities under relevant laws or regulations before
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,
traffic control system, automotive and transportation equipment, combustion equipment, safety
devices, life support system etc.) should first contact us.
6. We are making our continuous effort to improve the quality and reliability of our products, but
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.
Halogen Free
For the conservation of the global environment, Ricoh is advancing the decrease of the negative environmental impact material.
After Apr. 1, 2006, we will ship out the lead free products only. Thus, all products that will be shipped from now on comply with RoHS Directive.
Basically after Apr. 1, 2012, we will ship out the Power Management ICs of the Halogen Free products only. (Ricoh Halogen Free products are
also Antimony Free.)
RICOH COMPANY, LTD.
Electronic Devices Company
http://www.ricoh.com/LSI/
RICOH COMPANY, LTD.
Electronic Devices Company
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