L4978D STMicroelectronics, L4978D Datasheet

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L4978D

Manufacturer Part Number
L4978D
Description
IC REG SW STEP DOWN 2A 16-SOIC
Manufacturer
STMicroelectronics
Type
Step-Down (Buck)r
Datasheet

Specifications of L4978D

Internal Switch(s)
Yes
Synchronous Rectifier
No
Number Of Outputs
1
Voltage - Output
3.3 ~ 50 V
Current - Output
2A
Frequency - Switching
100kHz ~ 300kHz
Voltage - Input
8 ~ 55 V
Operating Temperature
-40°C ~ 150°C
Mounting Type
Surface Mount
Package / Case
16-SOIC (0.300", 7.5mm Width)
Power - Output
800mW
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
497-5794-5

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1
2
The L4978 is a step down monolithic power
switching regulator delivering 2A at a voltage be-
tween 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 R
Figure 2. Typical Application Circuit
May 2005
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 300KHz
VOLTAGE FEEDFORWARD
ZERO LOAD CURRENT OPERATION
INTERNAL CURRENT LIMITING (PULSE-
BYPULSE AND HICCUP MODE)
INHIBIT FOR ZERO CURRENT
CONSUMPTION
PROTECTION AGAINST FEEDBACK
DISCONNECTION
THERMAL SHUTDOWN
SOFT START FUNCTION
Features
DESCRIPTION
Vi=8V to 55V
220µF
63V
C
1
dson
220nF
C
7
of 0.25Ω) to obtain very high
100nF
2.7nF
20K
R
C
C
2A STEP DOWN SWITCHING REGULATOR
1
2
5
5
3
2
7
L4978
9.1K
R
22nF
2
C
4
efficency and high switching speed.
A switching frequency up to 300KHz is achievable
(the maximum power dissipation of the packages
must be observed). A wide input voltage range be-
tween 8V to 55V and output voltages regulated
from 3.3V to 50V cover the majority of today’s ap-
plications. Features of this new generations of DC-
DC converter include pulse-by-pulse current limit,
hiccup mode for short circuit protection, voltage
feedforward
against feedback loop disconnection, inhibit for
zero current consumption and thermal shutdown.
The device is available in plastic dual in line, DIP-
8 for standard assembly, and SO16W for SMD as-
sembly.
Figure 1. Packages
Table 1. Order Codes
1
100nF
6
L4978D013TR
C
Part Number
6
D98IN837A
L4978D
8
4
L4978
PS3L60U
DIP-8
D1
ST
regulation,
(77120)
126µH
L1
330µF
C
8
soft-start,
SO16 in Tape & Reel
V
Package
O
SO16W
=3.3V/2A
DIP-8
SO16
L4978
protection
Rev. 9
1/13

Related parts for L4978D

L4978D Summary of contents

Page 1

... The device is available in plastic dual in line, DIP- 8 for standard assembly, and SO16W for SMD as- sembly 20K L4978 2.7nF 22nF DIP-8 Part Number L4978 L4978D L4978D013TR SO16 in Tape & Reel regulation, soft-start 126µH (77120 100nF 330µF PS3L60U D98IN837A L4978 SO16W Package DIP-8 SO16 protection =3 ...

Page 2

L4978 Table 2. Block Diagram THERMAL SHUTDOWN 2 SS_INH INHIBIT SOFTSTART 7 COMP 8 E/A FB 3.3V OSCILLATOR 3 OSC Figure 3. Pins Connection (Top view) GND 1 SS_INH 2 OSC 3 OUT 4 D97IN595 DIP-8 Table 3. Pin Description ...

Page 3

Table 3. Pin Description (continued) N° Pin Name OUT BOOT 7 13 COMP (*) Pins 10, 15 and 16 are not internally, electrically connected ...

Page 4

L4978 Table 6. Electrical Characteristcs (T = 25° 2.7nF osc osc to T from 0 to 125°C j Symbol Parameter DYNAMIC CHARACTERISTIC V Operating input voltage range I V Output voltage o V Dropout voltage d ...

Page 5

Table 6. Electrical Characteristcs (T = 25° 2.7nF osc osc to T from 0 to 125°C j Symbol Parameter OSCILLATOR SECTION Ramp Valley Ramp peak Maximum duty cycle Maximum Frequency Figure 4. Test and evaluation board ...

Page 6

L4978 Figure 6. Quiescent drain current vs. input voltage. Iq (mA) 200KHz R =22K 1 C =1.2nF Tamb=25˚ Figure 7. Quiescent ...

Page 7

Figure 12. Switching Frequency vs. input voltage.. fsw (KHz) 107.5 105.0 102.5 100.0 97.5 95.0 92.5 90 Figure 13. Switching frequency vs. junction temperature. fsw (KHz) 105 100 ...

Page 8

L4978 Figure 18. Efficiency vs. output current. . η (%) 90 V =12V CC V =24V =48V 0.2 0.4 0.6 0.8 1.0 1.2 1.4 I Figure 19. Efficiency vs. output ...

Page 9

Figure 24. Load transient. . Figure 25. Line transient ( 1ms/DIV Figure 26. Soft start capacitor selection Vs inductor and V . ccmax L 680nF (µH) fsw=100KHz 400 ...

Page 10

L4978 3 Package Informations Figure 29. DIP-8 Mechanical Data & Package Dimensions mm DIM. MIN. TYP. MAX. A 3.32 a1 0.51 B 1.15 1.65 b 0.356 0.55 b1 0.204 0.304 D 10.92 E 7.95 9.75 e 2.54 e3 7.62 e4 ...

Page 11

Figure 30. SO16 Wide Mechanical Data & Package Dimensions mm DIM. MIN. TYP. MAX. A 2.35 2.65 A1 0.10 0.30 B 0.33 0.51 C 0.23 0.32 (1) 10.10 10. 7.40 7.60 e 1.27 H 10.0 10.65 h 0.25 ...

Page 12

L4978 Table 7. Revision History Date Revision October 2001 May 2005 12/13 8 First Issue 9 Modified D1 on the Fig. 4. Description of Changes ...

Page 13

... No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics ...

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