A6985F datasheet, PDF - EEWORLD Datasheet

A6985F: DescriptionConv DC-DC 4V to 38V Synchronous Step Down Single-Out 0.85V to 38V 0.5A Automotive 16-Pin HTSSOP EP Tube; File Size2MB，82 Pages; ManufacturerSTMicroelectronics; Websitehttp://www.st.com/

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A6985F Overview

Conv DC-DC 4V to 38V Synchronous Step Down Single-Out 0.85V to 38V 0.5A Automotive 16-Pin HTSSOP EP Tube

A6985F Parametric

Parameter Name	Attribute value
EU restricts the use of certain hazardous substances	Compliant
ECCN (US)	EAR99
Part Status	Active
HTS	8542.39.00.01
Type	Synchronous Step Down
Output Type	Adjustable
Switching Frequency (kHz)	250 to 2000
Switching Regulator	Yes
Number of Outputs	1
Output Voltage (V)	0.85 to 38
Maximum Output Current (A)	0.5
Minimum Input Voltage (V)	4
Maximum Input Voltage (V)	38
Maximum Low Level Output Voltage (V)	0.6
Maximum High Level Output Voltage (V)	1.4(Min)
Operating Supply Voltage (V)	4 to 38
Typical Switch Current (A)	0.65
Typical Quiescent Current (uA)	30
Minimum Operating Temperature (°C)	-40
Maximum Operating Temperature (°C)	150
Supplier Temperature Grade	Automotive
Packaging	Tube
Supplier Package	HTSSOP EP
Pin Count	16
Standard Package Name	SOP
Mounting	Surface Mount
Package Height	1
Package Length	5
Package Width	4.4
PCB changed	16

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A6985F

Automotive 38 V, 500 mA synchronous step-down switching

regulator with 30

μA

quiescent current

Datasheet

production data

Description

The A6985F automotive grade device is a step-

down monolithic switching regulator able to

deliver up to 0.5 A DC. The output voltage

adjustability ranges from 0.85 V to VIN. The 100%

duty cycle capability and the wide input voltage

range meet the cold crank and load dump

specifications for automotive systems. The “Low

Consumption Mode” (LCM) is designed for

applications active during car parking, so it

maximizes the efficiency at light-load with

controlled output voltage ripple. The “Low Noise

Mode” (LNM) makes the switching frequency

constant and minimizes the output voltage ripple

overload current range, meeting the low noise

application specification like car audio. The output

voltage supervisor manages the reset phase for

any digital load (µC, FPGA). The RST open

collector output can also implement output

voltage sequencing during the power-up phase.

The synchronous rectification, designed for high

efficiency at medium - heavy load, and the high

switching frequency capability make the size of

the application compact. Pulse by pulse current

sensing on both power elements implements an

effective constant current protection.

HTSSOP16 (R

= 40 °C/W)

Features



AEC-Q100 qualified



0.5 A DC output current



4 V to 38 V operating input voltage



Low consumption mode or low noise mode



30 µA I

at light-load (LCM V

OUT

= 3.3 V)



8 µA I

Q-SHTDWN



Fixed output voltage (3.3 V and 5 V) or

adjustable from 0.85 V to V



Adjustable f

(250 kHz - 2 MHz)



Embedded output voltage supervisor



Synchronization



Adjustable soft-start time



Internal current limiting



Overvoltage protection



Output voltage sequencing



Peak current mode architecture



DSON HS

= 360 m, R

DSON LS

= 150 m



Thermal shutdown

Applications



Designed for automotive systems



Battery powered applications



Car body applications (LCM)



Car audio and low noise applications (LNM)

February 2017

This is information on a product in full production.

DocID027738 Rev 6

1/82

www.st.com

Contents

A6985F

Contents

Application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

2.1

2.2

2.3

2.4

2.5

Pin connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Thermal data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

ESD protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Datasheet parameters over the temperature range . . . . . . . . . . . . . . . 14

Functional description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

5.1

5.2

5.3

Power supply and voltage reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Switchover feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Voltages monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Soft-start and inhibit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

5.3.1

5.3.2

Ratiometric startup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Output voltage sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

5.4

5.5

5.6

5.7

5.8

Error amplifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Output voltage line regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Output voltage load regulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

High-side switch resistance vs. input voltage . . . . . . . . . . . . . . . . . . . . . . 27

Light-load operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

5.8.1

5.8.2

5.8.3

Low noise mode (LNM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Low consumption mode (LCM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Quiescent current in LCM with switchover . . . . . . . . . . . . . . . . . . . . . . . 34

5.9

Switchover feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

5.9.1

5.9.2

LCM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

LNM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

5.10

Overcurrent protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

OCP and switchover feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

2/82

DocID027738 Rev 6

A6985F

Contents

5.11

5.12

Overvoltage protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

Thermal shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Closing the loop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

6.1

6.2

6.3

(s) control to output transfer function . . . . . . . . . . . . . . . . . . . . . . . . 43

Error amplifier compensation network . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Voltage divider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

6.3.1

6.3.2

Internal voltage divider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

External voltage divider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

6.4

6.5

Total loop gain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Compensation network design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Application notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

7.1

7.2

7.3

7.4

7.5

7.6

Output voltage adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

Switching frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

MLF pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Voltage supervisor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Synchronization (LNM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Design of the power components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

7.6.1

7.6.2

7.6.3

Input capacitor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Inductor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Output capacitor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Application board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

8.1

8.2

8.3

A6985F3V3 evaluation board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

A6985F5V evaluation board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

A6985F (V

OUT

= 6 V) evaluation board . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Efficiency curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

EMC testing results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73

Package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

11.1

HTSSOP16 package information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79

DocID027738 Rev 6

3/82

A6985F Related Products

	A6985F	A6985F5V	A6985F3V3
Description	Conv DC-DC 4V to 38V Synchronous Step Down Single-Out 0.85V to 38V 0.5A Automotive 16-Pin HTSSOP EP Tube	Conv DC-DC 4V to 38V Synchronous Step Down Single-Out 5V 0.5A Automotive 16-Pin HTSSOP EP Tube	Conv DC-DC 4V to 38V Synchronous Step Down Single-Out 3.3V 0.5A Automotive 16-Pin HTSSOP EP Tube
EU restricts the use of certain hazardous substances	Compliant	Compliant	Compliant
ECCN (US)	EAR99	EAR99	EAR99
Part Status	Active	Active	Active
Type	Synchronous Step Down	Synchronous Step Down	Synchronous Step Down
Output Type	Adjustable	Fixed	Fixed
Switching Frequency (kHz)	250 to 2000	250 to 2000	250 to 2000
Switching Regulator	Yes	Yes	Yes
Number of Outputs	1	1	1
Output Voltage (V)	0.85 to 38	5	3.3
Maximum Output Current (A)	0.5	0.5	0.5
Minimum Input Voltage (V)	4	4	4
Maximum Input Voltage (V)	38	38	38
Maximum Low Level Output Voltage (V)	0.6	0.6	0.6
Maximum High Level Output Voltage (V)	1.4(Min)	1.4(Min)	1.4(Min)
Operating Supply Voltage (V)	4 to 38	4 to 38	4 to 38
Typical Switch Current (A)	0.65	0.65	0.65
Typical Quiescent Current (uA)	30	30	30
Minimum Operating Temperature (°C)	-40	-40	-40
Maximum Operating Temperature (°C)	150	150	150
Supplier Temperature Grade	Automotive	Automotive	Automotive
Packaging	Tube	Tube	Tube
Supplier Package	HTSSOP EP	HTSSOP EP	HTSSOP EP
Pin Count	16	16	16
Standard Package Name	SOP	SOP	SOP
Mounting	Surface Mount	Surface Mount	Surface Mount
Package Height	1	1	1
Package Length	5	5	5
Package Width	4.4	4.4	4.4
PCB changed	16	16	16
HTS	8542.39.00.01	-	8542.39.00.01

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