switching regulator. L7986TA Datasheet

L7986TA regulator. Datasheet pdf. Equivalent

L7986TA Datasheet
Recommendation L7986TA Datasheet
Part L7986TA
Description 3A step-down switching regulator
Feature L7986TA; L7986TA 3 A step-down switching regulator Datasheet − production data Features ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ .
Manufacture STMicroelectronics
Datasheet
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STMicroelectronics L7986TA
L7986TA
3 A step-down switching regulator
Features
3 A DC output current
4.5 V to 38 V input voltage
Output voltage adjustable from 0.6 V
250 kHz switching frequency, programmable
up to 1 MHz
Internal soft-start and enable
Low dropout operation: 100% duty cycle
Voltage feed-forward
Zero load current operation
Overcurrent and thermal protection
HSOP8 package
Guarantee overtemperature range (-40 °C to
125 °C)
Applications
Automotive:
– Car audio, car infotainment
Industrial:
– PLD, PLA, FPGA, chargers
Networking: XDSL, modems, DC-DC modules
Computer:
– Optical storage, hard disk drive, printers
LED driving
Datasheet production data
HSOP8 exposed pad
Description
The L7986TA is a step-down switching regulator
with 3.7 A (min.) current limited embedded power
MOSFET, so it is able to deliver up to 3 A current
to the load depending on the application
conditions.
The input voltage can range from 4.5 V to 38 V,
while the output voltage can be set starting from
0.6 V to VIN.
Requiring a minimum set of external components,
the device includes an internal 250 kHz switching
frequency oscillator that can be externally
adjusted up to 1 MHz.
The HSOP package with exposed pad allows the
reduction of RthJA down to 40 °C/W.
October 2012
This is information on a product in full production.
Doc ID 022098 Rev 3
1/43
www.st.com
43
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STMicroelectronics L7986TA
Contents
Contents
L7986TA
1 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1 Oscillator and synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.2 Soft-start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.3 Error amplifier and compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.4 Overcurrent protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
5.5 Enable function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.6 Hysteretic thermal shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.1 Input capacitor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
6.2 Inductor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
6.3 Output capacitor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
6.4 Compensation network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
6.4.1 Type III compensation network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
6.4.2 Type II compensation network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
6.5 Thermal considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.6 Layout considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
6.7 Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
7 Application ideas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.1 Positive buck-boost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
7.2 Inverting buck-boost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2/43 Doc ID 022098 Rev 3
Free Datasheet http://www.datasheet4u.com/



STMicroelectronics L7986TA
L7986TA
Contents
8 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
9 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Doc ID 022098 Rev 3
3/43
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