Diodes AP5100WG Schematic

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Y

Description

1.2A STEP-DOWN CONVERTER with 1.4MHz SWITCHING

Pin Assignments

The AP5100 is a current mode step-down converter with a built-in power MOSFET to enable smallest solution size power conversion.

With the low series resistance power switch it enables a

BST

constant output current of up to 1.2A over a wide input supply range. The load and line regulation has excellent response

GND

time over the operating input voltage and temperature range. The AP5100 is self protected, through a cycle-by-cycle

FB

current limiting algorithm and an on chip thermal protection. The AP5100 will provide the voltage conversion with a low

count of widely available standard external components. The AP5100 is available in SOT26 package.

Features

• VIN 4.75V to 24V

• Load current of up to 1.2A

• Internal Power MOSFET

• Stable with Low ESR Ceramic Output Capacitors

• Up to 90% Efficiency

• 0.1µA Shutdown Mode

Applications

• Distributed Power Systems

• Battery Charger

• Pre-Regulator for Linear Regulators

• WLED Drivers

• Fixed 1.4MHz Frequency

• Thermal Shutdown

• Cycle-by-Cycle Over Current Protection

• Resistor divider adjustable Output: 0.81V to 15V

• SOT26: Available in “Green” Molding Compound

(No Br, Sb)

• Lead Free Finish/RoHS Compliant (Note 1)

Notes: 1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at

http://www.diodes.com/products/lead_free.html.

Typical Application Circuit

100

(%)

IEN

EFFI

90

80

70

60

V = 12V

IN

L = 3.3µH

V = 5V

OUT

V = 3.3V

OUT

5

IN

AP5100

4

EN

GND

OFF

V

IN

C1

ON

( Top View )

1

2

3

SOT26

1

BST

6

SW

3

FB

AP5100

FREQUENCY

SW

6

5

IN

7

4

EN

C3

.L1

V

OUT

D1

R1

R2

C6

C2

50

40

LOAD CURRENT (A)

Fig. 1 Efficiency vs. Load Current

AP5100

Document number: DS32130 Rev. 3 - 2

0.6 0.8 1.0 1.200.20.4

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Figure 2. Typical Application Circuit

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Typical Application Circuit (cont.)

5

V

IN

10µF

OFF

C1

25V

R3

100kohm

ON

IN

4

EN

AP5100

1.2A STEP-DOWN CONVERTER with 1.4MHz SWITCHING FREQUENCY

SW

FB

1

6

3

C3

22nF

D1

B230A

L1

3.3µH

R1

49.9kohm

R2

16.2kohm

C6

100pF

V

3.3V

C2

22µF

6.3V

OUT

BST

AP5100

GND

6V -12V

OFF

Figure 3. 1.4MHz, 3.3V Output at 1A Step-Down Converter

5

4

IN

AP5100

EN

- Vout

GND

Figure 4. White LED Driver Application

V

IN

C1

10µF

25V

ON

R3

100Kohm

BST

SW

FB

1

C3

10nF

6

3

200Kohm

D1

1N5819HW-7

- Vout -Vout

R4

1%

L1

10µH

40 ohm

-Vout

R2

1%

C2

10µF

16V

LED1

LED 2

LED 3

AP5100

Document number: DS32130 Rev. 3 - 2

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1.2A STEP-DOWN CONVERTER with 1.4MHz SWITCHING

Pin Descriptions

Pin Name Pin #

Bootstrap. To form a boost circuit, a capacitor is connected between SW and BST pins to form a

BST 1

GND 2

FB 3

EN 4

IN 5

SW 6 Switch Output. This is the reference for the floating top gate driver.

floating supply across the power switch driver. This capacitor is needed to drive the power switch’s gate above the supply voltage. Typical values for C

Ground. This pin is the voltage reference for the regulated output voltage. All control circuits are referenced to this pin. For this reason care must be taken in its layout.

Feedback. To set the output voltage, connect this pin to the output resistor divider or directly to V

. To prevent current limit run away during a current limit condition, the frequency foldback

OUT

comparator lowers the oscillator frequency when the FB voltage is below 400mV. On/Off Control Input. Do not leave this pin floating. To turn the device ON, pull EN above 1.2V and

to turn it off pull below 0.4V. If enable/disable is not used, connect a 100k resistor between EN to V

Supply Voltage. The AP5100 operates from a +4.75V to +24V unregulated input. A decoupling capacitor C1 is required to prevent large voltage spikes from appearing at the input. Place this capacitor near the IC.

Description

BST

Functional Block Diagram

range from 0.1µF to 1µF.

.

IN

AP5100

FREQUENCY

AP5100

Document number: DS32130 Rev. 3 - 2

Σ

Figure 5. Functional Block Diagram

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AP5100

Absolute Maximum Ratings (Note 2)

Symbol Description Rating Unit

ESD HBM Human Body Model ESD Protection 3 KV

ESD MM Machine Model ESD Protection 300 V

VIN

VSW

V

BST

TST

TJ TL



JA



JC

Notes: 2. Exceeding these ratings may damage the device.

3. Test condition for SOT26: Measured on approximately 1” square of 1 oz copper.

Recommended Operating Conditions (Note 4)

Symbol Description Rating Unit

VIN

TA

V

OUT

Note: 4. The device function is not guaranteed outside of the recommended operating conditions.

AP5100

Document number: DS32130 Rev. 3 - 2

Supply Voltage Switch Voltage Boost Voltage All Other Pins –0.3 to +6 V Storage Temperature -65 to +150 °C Junction Temperature +150 °C Lead Temperature +260 °C Junction to Ambient Thermal Resistance (Note 3) 140 °C/W Junction to Case Thermal Resistance (Note 3) 35 °C/W

Supply Voltage 4.75 to 24 °C Operating Ambient Temperature Range -25 to +85 °C Output Voltage 0.81 to 15 V

1.2A STEP-DOWN CONVERTER with 1.4MHz SWITCHING FREQUENCY

26

-0.3 to VIN +0.3 VSW +6

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Diodes AP5100WG Schematic [ru]