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The L4978 is a step down monolithic power switching regulator delivering 2A at a voltage between 3.3V and 50V (selected by a simple external divider). Realized in BCD mixed technology,the device uses an internal power D-MOS transistor (with a typical Rdson of 0.25W) to obtain very high efficency and high switching speed.
A switching frequency up to 500KHz is achievable (the maximum power dissipation of the packages 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 converter include pulse-by-pulse current limit, hiccup mode for short circuit protection, voltage feedforward regulation, soft-start, protection against feedback loop disconnection, inhibit for zero current consumption and thermal shutdown.
The device is available in plastic dual in line,MINIDIP 8 for standard assembly, and SO16W for SMD assembly.
L4978 Maximum Ratings
Symbol
Parameter
Value
Unit
Minidip
SO16
V5
V11
Input voltage
58
V
V4
V5,V6
Output DC voltage Output peak voltage at t = 0.1s f=200KHz
-1 -5
V V
I4
I5,I6
Maximum output current
int. limit.
V6-V5
V12-V11
14
V
V6
V12
Bootstrap voltage
70
V
V7
V13
Analogs input voltage (VCC = 24V)
12
V
V2
V3
Analogs input voltage (VCC = 24V)
13
V
V8
V14
(VCC = 20V)
6 -0.3
V V
Ptot
Power dissipation a Tamb 60°C
Minidip
1
W
SO16
0.8
W
Tj,Tstg
Junction and storage temperature
-40to150
°C
L4978 Features
·UP TO 2A STEP DOWN CONVERTER ·OPERATING INPUT VOLTAGE FROM 8V TO 55V ·PRECISE 3.3V (±1%) INTERNAL REFERENCE VOLTAGE ·OUTPUT VOLTAGE ADJUSTABLE FROM 3.3V TO 50V ·SWITCHING FREQUENCY ADJUSTABLE UP TO 500KHz ·VOLTAGEFEEDFORWARD ·ZERO LOAD CURRENT OPERATION ·INTERNAL CURRENT LIMITING (PULSE-BYPULSE AND HICCUPMODE) ·INHIBIT FOR ZERO CURRENT CONSUMPTION ·PROTECTION AGAINST FEEDBACK DISCONNECTION ·THERMAL SHUTDOWN ·SOFT START FUNCTION