R1272S Series
AEC-Q100 Compliant
34 V Input Synchronous Step-down DC / DC Controller for Automotive Applications
NO.EC-351-190128
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 provide 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.
FEATURES
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(1)
(2)
Operating Voltage (Maximum Rating) ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 4.0 V to 34 V (36 V)
Operating Temperature Range ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ −40°C to 125°C
Start-up Voltage ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 4.5 V
Output Voltage ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 0.7 V to 5.3 V
Feedback Voltage Tolerance ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 0.64 V ± 1%
Consumption Current at No Load (at VFM mode) ꞏꞏꞏꞏꞏꞏꞏꞏ Typ.15 µA
Adjustable Oscillation Frequency
(1)
ꞏꞏꞏꞏꞏꞏꞏꞏ ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 250 kHz to 1 MHz
Synchronizable Clock Frequency
(1)
ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ 250 kHz to 1 MHz
Spreading Rate for SSCG ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ Typ. ±3.6%
Minimum On-Time ꞏꞏꞏ ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ Typ.100 ns
Minimum Off-Time ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ Typ.120 ns (at regulation mode)
At dropout, actual minimum off-time is reduced.
Adjustable Soft-start Time
(2)
ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ Typ.500 µs
Pre-bias Start-up
Anti-phase Clock Output
Thermal Shutdown Function ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ Tj = 160ºC (Typ.)
Under Voltage Lockout (UVLO) Functionꞏꞏꞏꞏꞏꞏꞏꞏꞏ ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ Typ. 3.3 V
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
NO.EC-351-190128
● Over Voltage Detection (OVD) Function ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ FB pin voltage (V
FB
) + 10% (Typ.)
Detection/Release Hysteresis ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ FB pin voltage (V
FB
) x 3% (Typ.)
● Under Voltage Detection (UVD) Function ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ
Detection/Release Hysteresis ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ
● Over-current Protection ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ
● Selectable Current Limit Threshold ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ
● Power Good Output ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ
● Package ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ
FB pin voltage (V
FB
) - 10% (Typ.)
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
● Power source for car accessories including car audio equipment, car navigation system, and ETC system.
● Power source for control units including EV inverter and charge control.
SELECTION GUIDE
The function and setting for the ICs are selectable at the user’s request.
Product Name
R1272SxxyA-E2-#E
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
# : Select the quality class.
Operating Temperature Range
A
−40°C to 125°C
K
−40°C to 125°C
Test Temp.
25°C, High
Low, 25°C, High
2
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