ISL8104EVAL1Z Intersil, ISL8104EVAL1Z Datasheet

ISL8104EVAL1Z

Manufacturer Part Number

ISL8104EVAL1Z

Description

EVALUATION BOARD FOR ISL8104

Manufacturer

Intersil

Datasheets

1.ISL8104IBZ.pdf (14 pages)

2.ISL8104EVAL1Z.pdf (13 pages)

Specifications of ISL8104EVAL1Z

Main Purpose

DC/DC, Step Down

Outputs And Type

1, Non-Isolated

Voltage - Output

1.8V

Current - Output

20A

Voltage - Input

8 ~ 14.4V

Regulator Topology

Buck

Frequency - Switching

300kHz

Board Type

Fully Populated

Utilized Ic / Part

ISL8104

Lead Free Status / RoHS Status

Lead free / RoHS Compliant

Power - Output

Current page: 1 of 13
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Introduction

The ISL8104 is a simple single-phase PWM controller for a

synchronous buck converter with integrated MOSFET driver

that operates from +8V to +14.4V bias supply voltage. The

ISL8104 employs voltage-mode control with dual-edge

modulation to achieve fast transient response. The controller

features the ability to safely start-up into prebiased output

loads and provides protection against overcurrent fault

events. Overcurrent protection is implemented using topside

MOSFET r

sensing resistor.

The ISL8104 evaluation board highlights the operations of

the controller in a DC/DC application.

ISL8104 Reference Design

The evaluation board is designed to optimize for the output

voltage and current specifications shown in Table 1.

Design Procedure

The following sections illustrate simple design steps and

component selections for a converter using the ISL8104.

Output Inductor Selection

The output inductor is chosen by the desired inductor ripple

current, which is typically set to be approximately 40% of the

rated output current. The desired output inductor can be

calculated using Equation 1:

In the evaluation board, a 0.68µH inductor with 1.6mΩ DCR

(Vishay’s IHLP5050FD-R68) is employed. This yields

approximately 0.64W conduction loss in the inductor.

Output Capacitor Selection

The output capacitors are generally selected by the output

voltage ripple and load transient response requirements.

Input Voltage (V

Output Voltage (V

Output Voltage Ripple (V

Continuous Load Current

Switching Frequency

TABLE 1. ISL8104 EVALUATION BOARD DESIGN

------------------------------- -

0.66μH

14.4 1.8

------------------------- -

0.4 20

–

ΔI

PARAMETER

–

⋅

DS(ON)

OUT

PARAMETERS

---------- -

14.4

1.8

OUT

)

--------------- -

sensing, eliminating the need for a current

OUT

)

--------------------- -

300

RIPPLE

----------- -

×10

)

MIN

Application Note

30mV

300kHz

1.8V

TYP

12V

P-P

14.4V

MAX

20A

(EQ. 1)

1-888-INTERSIL or 1-888-468-3774

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

Using the ISL8104 PWM Controller

ESR and capacitor charge are major contributions to the output

voltage ripple. Assuming that the total output capacitance is

sufficient, then the output voltage ripple is dominated by the

ESR, which can be calculated using Equation 2.

To meet the 30mV

effective ESR should be less than 4mΩ.

The output voltage response to a transient load is

contributed from ESL, ESR and the amount of output

capacitance. With V

excursions can be approximated using Equation 3:

With 0.68µH inductor and 0A to 20A step load, the total output

capacitance of 1900µF is required for 80mV output voltage

transient. In the evaluation board, four of Fujitsu’s

FP-4R0RE561M-L8 are employed.

Input Capacitor Selection

The input bulk capacitors selection criteria are based on the

capacitance and RMS current capability. The RMS current

rating requirement for the input capacitor is approximated in

Equation 4:

In this application, the RMS current for the input capacitor is

7.2A; therefore, three of Sanyo’s 35ME330AX are used.

Small ceramic capacitors for high frequency decoupling are

also required to control the voltage overshoot across the

MOSFETs.

MOSFET Selection

The ISL8104 requires two N-Channel power MOSFETs as

the main and the synchronous switches. These should be

selected based in r

thermal management requirements.

The total power loss on MOSFET consists of conduction loss

and switching loss, as shown in Equation 5:

In this relatively small duty cycle design, the low-side

MOSFET conducts current most of the time. To optimize the

converter efficiency, select the high-side MOSFET with low

gate charge for fast switching transition and low-side

MOSFET with low r

The budget power losses in each high-side and low-side

MOSFETs is 1W.

ΔV

IN RMS

RIPPLE

MOSFET TOT

(

------------------------------------ -

OUT

)

All other trademarks mentioned are the property of their respective owners.

L I

(

June 9, 2009

⋅

ΔI

Intersil (and design) is a registered trademark of Intersil Americas Inc.

tran

⋅

)

OUT

⋅

ESR

(

D D

P-P

DS(ON)

–

cond

DS(ON)

>>V

output voltage ripple requirement, the

)

Evaluation Board

OUT

I Δ

------- - D

, gate supply requirements and

, the amplitude of the voltage

----------

VIN

AN1416.1

(EQ. 3)

(EQ. 2)

(EQ. 4)

(EQ. 5)

Related parts for ISL8104EVAL1Z

ISL8104EVAL1Z Summary of contents

Page 1

... IN OUT 2 ⋅ tran ⋅ V OUT V I Δ ---------- ------- - D = – VIN 12 , gate supply requirements and DS(ON cond sw . DS(ON) | Intersil (and design registered trademark of Intersil Americas Inc. Copyright Intersil Americas Inc. 2008, 2009. All Rights Reserved (EQ. 2) (EQ. 3) (EQ. 4) (EQ. 5) ...

Page 2

LOW-SIDE MOSFET SELECTION The low-side MOSFET’s RMS current is approximated in Equation 6: ΔI ⎛ ⋅ ⋅ ⋅ ⎜ ----- - ------------ - – RMS OUT 12 ⎝ ...

Page 3

... ESR be found in TB417 entitled “Designing Stable Compensation Networks for Single Phase Voltage Mode Buck Regulators”. Evaluation Board Performance Figures 2 and 3 show photographs of the ISL8104EVAL1Z and ISL8104EVAL2Z boards, respectively. (EQ. 15) for the target 4 (EQ. 16) ⋅ ...

Page 4

FIGURE 3. ISL8104EVAL2Z Power and Load Connections Terminals J1 and J2 are connected to the input of the power stage. For single rail supply, the IC bias supply can be tied to the converter input supply through pin 1 and ...

Page 5

... FIGURE 10. EVALUATION BOARD EFFICIENCY (V References For Intersil documents available on the web http://www.intersil.com/. 1. ISL8104 Data Sheet “8V to 14V, Single-Phase Synchronous Buck Pulse-Width Modulation (PWM) Controller With Integrated Gate Drivers”, Intersil Corporation 2. Tech Brief TB417 , “Designing Stable Compensation Networks for Single Phase Voltage Mode Buck Regulators” ...

Page 6

... ISL8104EVAL1Z Schematic J6 3 VBIAS J7 R9 4.7 GND R15 R7 DNP 1.15k 63. 1µF C11 0.1µ 1000pF VCC C2 U1 82pF FSET 1 VCC VCC 14 1 FSET 2 2 TSOC PVCC PVCC 13 TSOC BGATE R8 SS BGATE 2.2nF 44. COMP PGND PGND 11 20k COMP 5 FB BOOT 10 FB ...

Page 7

... ISL8104EVAL1Z Bill of Materials ID REFERENCE QTY ISL8104IBZ BSC080N30LS BSC030N03LS DNP BAT54C IHLP5050FD-R68 7 SW1 1 GT11MSCKE CAPACITORS C2, C4, C12, C29,C30 4 12 C6, C10, C25, C26, C27, 6 C28 13 C8, C11 2 14 C13 1 15 C18, C19, C20 3 35ME330AX 16 C21, C22, C23, C24 4 FP-4R0RE561M-L8R Polymer Alumium 17 C5, C9, C14, C15, C16, C17 DNP ...

Page 8

... ISL8104EVAL1Z Bill of Materials ID REFERENCE QTY 33 J6 1514 68000-236-1X3 35 TP1 through TP7 7 5002 36 TP8 DNP 8 Application Note 1416 (Continued) PART NUMBER PART TYPE Turrett Post Test Point DESCRIPTION PACKAGE Conn-Turret, Terminal Post, TH, ROHS 3-pin Jumper Conn-Mini Test Point, Vertical, White, ROHS VENDOR ...

Page 9

... ISL8104EVAL1Z Printed Circuit Board Layers FIGURE 11. ISL8104EVAL1Z - TOP LAYER (SILKSCREEN) FIGURE 13. ISL8104EVAL1Z - LAYER 2 FIGURE 15. ISL8104EVAL1Z - BOTTOM LAYER 9 Application Note 1416 FIGURE 12. ISL8104EVAL1Z - TOP LAYER (COMPONENT SIDE) FIGURE 14. ISL8104EVAL1Z - LAYER 3 FIGURE 16. ISL8104EVAL1Z - BOTTOM LAYER (SOLDER SIDE) AN1416.1 June 9, 2009 ...

Page 10

ISL8104EVAL2Z Schematic VBIAS VBIAS GND R23 DNP DNP 10k 10k R5 63. 1µF 1uF 2 1 SSDONE VCC EPAD 0.1µ ...

Page 11

... Resistor, Film 1.15kΩ, 1%, 1/16W Resistor, Film 10Ω, 1%, 1/16W Resistor, Film 2.2Ω, 1%, 1/16W Blinding Post Conn-Gen, Bind. Post, RED, Thmbnut-Gnd PACKAGE VENDOR 16 Ld 4x4 MLFP Intersil TDSON-08 Infineon TDSON-08 Infineon SOT23 Onsemi Vishay C&K SMD 1206 Dialight SM_0603 ...

Page 12

ISL8104EVAL2Z Bill of Materials ID REFERENCE QTY PART NUMBER 33 J2 111-0703-001 34 J6 1514 68000-236-1x3 36 TP1 through TP7, 9 5002 TP9,TP10 37 TP8 DNP 12 Application Note 1416 (Continued) PART TYPE ...

Page 13

... Application Note or Technical Brief is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com 13 Application Note 1416 FIGURE 18. ISL8104EVAL2Z - TOP LAYER (COMPONENT SIDE) FIGURE 20. ISL8104EVAL2Z - LAYER 3 FIGURE 22. ISL8104EVAL1Z - BOTTOM LAYER (SOLDER SIDE) AN1416.1 June 9, 2009 ...

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