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L4971D013TR
1.5A STEP DOWN SWITCHING REGULATOR
UP TO 1.5A STEP DOWN CONVERTER
OPERATING INPUT VOLTAGE FROM 8V TO
55V
PRECISE 3.3V (±1%) INTERNAL REFER-
ENCE VOLTAGE
OUTPUT VOLTAGE ADJUSTABLE FROM
3.3V TO 50V
SWITCHING FREQUENCY ADJUSTABLE UP
TO 300KHz
VOLTAGE FEEDFORWARD
ZERO LOAD CURRENT OPERATION
INTERNAL CURRENT LIMITING (PULSE-BY-
PULSE AND HICCUP MODE)
INHIBIT FOR ZERO CURRENT CONSUMP-
TION
PROTECTION AGAINST FEEDBACK DIS-
CONNECTION
THERMAL SHUTDOWN
SOFT START FUNCTION
DESCRIPTIONThe L4971 is a step down monolithic power
switching regulator delivering 1.5A at a voltage
between 3.3V and 50V (selected by a simple ex-
ternal divider). Realized in BCD mixed technol-
ogy, the device uses an internal power D-MOS
transistor (with a typical Rdson of 0.25Ω) to ob-
tain very high efficency and high switching speed.
A switching frequency up to 300KHz is achiev-
able (the maximum power dissipation of the pack-
ages must be observed).
A wide input voltage range between 8V to 55V
and output voltages regulated from 3.3V to 50V
cover the majority of today’s applications.
Features of this new generations of DC-DC con-
verter include pulse-by-pulse current limit, hiccup
mode for short circuit protection, voltage feedfor-
ward regulation, soft-start, protection against
feedback loop disconnection, inhibit for zero cur-
rent consumption and thermal shutdown.
The device is available in plastic dual in line,
MINIDIP 8 for standard assembly, and SO16W
for SMD assembly.
L49711.5A STEP DOWN SWITCHING REGULATOR
TYPICAL APPLICATION CIRCUIT
PIN FUNCTIONS(*) Pins 1, 7, 8, 9, 10, 15 and 16 are not internally, electrically connected to the die.
PIN CONNECTIONS
BLOCK DIAGRAM
L4971
ELECTRICAL CHARACTERISTICS (Tj = 25°C, Cosc = 2.7nF, Rosc = 20kΩ, VCC = 24V, unless other-wise specified.) * Specification Refered to Tj from 0 to 125°C
THERMAL DATA(*) Package mounted on board.
ABSOLUTE MAXIMUM RATINGS
L4971
ELECTRICAL CHARACTERISTICS (continued)
L4971
Figure 1. Test and valuation board circuit.
Typical Performance (Using Evaluation Board) fsw = 100kHz
Figure 2. PCB and component layout of the figure 1.
L4971
5101520253035404550 Vcc(V)(mA)
D97IN724
Figure 3. Quiescent drain current vs. input
voltage. 0.2 0.4 0.6 0.8 1.0 1.2 1.4 IO(A)
(V)
D97IN734
Figure 7. Load regulation5 101520253035404550 VCC(V)60
Ibias
(μA)
D97IN732
Figure 5. Stand-by drain current vs. input
voltage-50 -30 -1010 30 50 70 90 110 Tj(˚C)
(mA)
D97IN731
Figure 4. Quiescent current vs. junction
temperature 20 40 60 80 R1(KΩ)5
fsw
(KHz)
D97IN784
Figure 8. Switching frquency vs. R1 and C25 101520253035404550 VCC(V)
(V)
D97IN733
Figure 6. Line Regulation
L4971
