R1272S-Y Series
34 V Input Synchronous Step-down DC / DC Controller for Industrial Applications
NO.EA-385-210910
OUTLINE
The R1272S is a step-down DC/DC controller which can generate an output voltage of 0.7 V to 5.3 V by driving
external high- / low-side NMOSs. By the adoption of a unique current mode PWM architecture without an
external current sense resistor, the R1272S can make up a stable DC/DC converter with high-efficiency even
if adding low Ron MOSFETs and a low DCR inductor externally. And, by the frequency characteristics
optimization with using external phase compensation capacitor, the R1272S can achieve a high-speed
response to variations of input voltage and load current. The user-settable oscillation frequency is adjustable
over a range of 250 kHz to 1 MHz
(1)
by external resistors, and also can be synchronized to an external clock.
Output Voltage Control Methods have three operating modes: Forced PWM mode, PLL_PWM mode, and
PWM/VFM Auto-switching mode. These modes are selectable according to conditions of the MODE pin.
Especially, the PWM/VFM Auto-switching mode can improve efficiency under light load conditions.
The R1272S can minimize the output voltage drop caused by an input voltage drop at cranking, with reducing
the operating frequency (the lowest possible limit is a quarter of the frequency) so that the off-duty is reduced.
Protection functions include a current limit function, an UVLO (Under Voltage Lock Out) function, an OVP (Over
Voltage Protection) function, a soft-start function, a low-inductor current shutdown function, and so on. Also, a
power good function provides the status of output with using a power good (PGOOD) pin.
For EMI reduction, SSCG (Spread-Spectrum Clock Generator) for diffused oscillation frequency at the PWM
operation is optionally available. The R1272S is available in HSOP-18 package.
This is a high-reliability semiconductor device for industrial application (-Y) that has passed both the screening
at high temperature and the reliability test with extended hours.
FEATURES
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(1)
(2)
Operating Voltage (Maximum Rating) ·······················
Operating Temperature Range ································
Start-up Voltage ···················································
Output Voltage ················· ···································
Feedback Voltage Tolerance ················· ·················
Consumption Current at No Load (at VFM mode) ········
Adjustable Oscillation Frequency
(1)
········ ···················
Synchronizable Clock Frequency
(1)
···························
Spreading Rate for SSCG ······································
Minimum On-Time ··· ············································
Minimum Off-Time ················································
4.0 V to 34 V (36 V)
-40°C
≤ Ta ≤ 105°C
4.5 V
0.7 V to 5.3 V
0.64 V ± 1%
Typ.15 µA
250 kHz to 1 MHz
250 kHz to 1 MHz
Typ. ±3.6%
Typ.100 ns
Typ.120 ns (at regulation mode)
At dropout, actual minimum off-time is reduced.
(2)
···································· Typ.500 µs
Adjustable Soft-start Time
Pre-bias Start-up
Anti-phase Clock Output
Thermal Shutdown Function ··································· Tj = 160ºC (Typ.)
The adjustable oscillation frequency range becomes 250 kHz
≤
f
OSC
≤
600 kHz when 0.7 V
≤ V
OUT
< 1.35V.
500 µs(Typ.) as a lower limit with using an external capacitor. Otherwise, available the tracking function through the
application of an external voltage.
1
R1272S-Y
NO.EA-385-210910
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Under Voltage Lockout (UVLO) Function········· ·········· Typ. 3.3 V
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Over Voltage Detection (OVD) Function ···················· FB pin voltage (V
FB
) + 10% (Typ.)
Detection/Release Hysteresis ································· FB pin voltage (V
FB
) x 3% (Typ.)
●
Under Voltage Detection (UVD) Function ··················· FB pin voltage (V
FB
) - 10% (Typ.)
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Detection/Release Hysteresis ·································
Over-current Protection··········································
Selectable Current Limit Threshold ···························
Power Good Output ··············································
Package ·····························································
FB pin voltage (V
FB
) x 3% (Typ.)
Hiccup-mode / Latch mode
50 mV / 70 mV / 100 mV
NMOS Open-drain Output
HSOP-18
APPLICATIONS
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Industrial equipments such as FA½ and smart meters.
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Equipments used under high-temperature conditions such as surveillance camera and vending machine.
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Equipments accompanied by self-heating such as motor and lighting.
SELECTION GUIDE
The function and setting for the ICs are selectable at the user’s request.
Product Name
R1272SxxyA-E2-YE
Package
HSOP-18
Quantity per Reel
1,000
Pb Free
Yes
Halogen Free
Yes
xx : Select the combination of processing and function.
xx
Over Current Protection
SSCG
00
Non-latch type hiccup mode
Disable
01
Latch mode
Disable
03
Latch mode
Enable
10
Non-latch type hiccup mode
Disable
11
Latch mode
Disable
13
Latch mode
Enable
Output Voltage Range
3.15 V < V
OUT
≤ 5.3 V
3.15 V < V
OUT
≤ 5.3 V
3.15 V < V
OUT
≤
5.3 V
0.7 V
≤
V
OUT
≤ 3.15 V
0.7 V
≤
V
OUT
≤ 3.15 V
0.7 V
≤
V
OUT
≤ 3.15 V
If required a version with SSCG function, please contact our sales offices.
y : Select the current limit threshold voltage.
y
1
2
3
Set Voltage for Current
Limit Threshold (Typ.)
50 mV
70 mV
100 mV
Reverse Current Detection
Value (Typ.)
25mV
35mV
50mV
2
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