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Partno	Mfg	Dc	Qty	Available	Descript
L7985	ST	N/a	99	avai	2A step-down switching regulator
L7985A	ST	N/a	15	avai	2A step-down switching regulator

L7985 ,2A step-down switching regulatorFeaturesDescription 2 A DC output currentThe L7985/A is a step-down switching regulator  4.5 V to ..
L7985A ,2A step-down switching regulatorFunctional description . . . . . . . 85.1 Oscillator and synchronization . . 95.2 Soft-sta ..
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L7986A ,3A step-down switching regulatorFeatures LED driving 3 A DC output currentDescription 4.5 V to 38 V input voltageThe L7986/A is ..
L7986TA ,3A step-down switching regulatorFunctional description . . . . . . . 85.1 Oscillator and synchronization . . 95.2 Soft-sta ..
L79L05ABD13TR ,NEGATIVE VOLTAGE REGULATORSL79L00SERIESNEGATIVE VOLTAGE REGULATORS■ OUTPUT CURRENT UP TO 100 mA■ OUTPUT VOLTAGES OF -5; -6; -8 ..
LC6529N ,4-Bit Microcomputer for Small-Scale Control ApplicationsOrdering number : EN*5117CMOS LSILC6529N, LC6529F, LC6529L4-Bit Microcomputer for Small-Scale Contr ..
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LC6543F ,CMOS LSI SINGLE-CHIP 4-BIT MICROCOMPUTER FOR SMALL-SCALE CONTROL-ORIENTED APPLICATIONSFeatures1) CMOS technology for a low-power operation (with instruction-controlled standby function) ..
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LC6543H ,CMOS LSI SINGLE-CHIP 4-BIT MICROCOMPUTERS FOR SMALL-SCALE CONTROL-ORIENTED APPLICATIONSFeatures1) CMOS technology for Iow-power operation (with instruction-gon2) ROM/RAML66543C/H ROM; 2K ..

L7985-L7985A
2A step-down switching regulator
September 2014 DocID022446 Rev 7 1/42
L7985
2 A step-down switching regulator
Datasheet - production data
Features 2 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 VFQFPN 3 x 3 - 10L and HSOP8 package
Applications Consumer: STB, DVD, DVD recorder, car
audio, LCD TV and monitors Industrial: PLD, PLA, FPGA, chargers Networking: XDSL, modems, DC-DC modules Computer: optical storage, hard disk drive,
printers, audio/graphic cards LED driving
Description
The L7985/A is a step-down switching regulator
with a 2.5 A (minimum) current limited embedded
power MOSFET, so it is able to deliver up to 2 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
QFN and the HSOP packages with exposed pad
allow the reduction of RthJA down to 60 °C/W and
40 °C/W respectively.
Figure 1. Application circuit
Contents L7985
2/42 DocID022446 Rev 7
Contents Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1 Oscillator and synchronization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.2 Soft-start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
5.3 Error amplifier and compensation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
5.4 Overcurrent protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.5 Enable function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.6 Hysteretic thermal shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 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 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
6.5 Thermal considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
6.6 Layout considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
6.7 Application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Application ideas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.1 Positive buck-boost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7.2 Inverting buck-boost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
DocID022446 Rev 7 3/42
L7985 Contents Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 Ordering information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Pin settings L7985
4/42 DocID022446 Rev 7
1 Pin settings
1.1 Pin connection
1.2 Pin description

Table 1. Pin description
DocID022446 Rev 7 5/42
L7985 Maximum ratings
2 Maximum ratings

3 Thermal data

Table 2. Absolute maximum ratings
Table 3. Thermal data Package mounted on demonstration board.

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