As1310

Page 1

AS1310 Dual 1.5MHz, 5V/0.8A Sync. Step-down Converter GENERAL DESCRIPTION

FEATURES           

High Efficiency：Up to 95% 1.5MHz Constant Switching Frequency 0.8A Available Load Current 2.5V to 6.5V Input Voltage Range: Output Voltage as low as 0.6V 100% Duty Cycle In Dropout Current Mode Control Short Circuit Protection Thermal Fault Protection <1μA Shutdown Current Package：TDFN-10(EP)

The AS1310 contains two independent 1.5MHz constant frequency current mode PWM step-down converter. Each converter integrates a main switch and a synchronous rectifier for high efficiency without an external Schottky diode. It is ideal for powering portable equipment that runs from a single cell Lithium-Ion (Li+) battery. Each converter can supply 0.8A (max.) of load current from a 2.5V to 6.5V input voltage. The output voltage can be regulated as low as 0.6V, The AS1310 can also run at 100% duty cycle for low dropout applications. The AS1310 is available in a low profile (1mm) 10-pin, TDFN package.

APPLICATIONS     

Cellular & Smart Phones Microprocessors and DSP Core Supplies PDAs & MP3 Player Digital Still and Video Cameras Portable instruments

TYPICAL APPLICATION CIRCUIT VIN=2.5V ~ 6.5V

R13 100K

OFF ON

VO1=1.8V, 0.8A max C12 10uF

1

EN1

8 IN1

L11 2.2uH

10 R11 300K C13 18pF R12 150K

2

3 IN2

AS1310

SW1 FB1

R23 100K

EN2

9

GND2 4

6 5 7

100 95

OFF ON L21 2.2uH

SW2 FB2

GND1

C21 4.7uF

R21 300K C23 R22 18pF 300K

VIN = 3.6V

90 VO2=1.2V, 0.8A max C22 10uF

Efficiency (%)

C11 4.7uF

Efficiency vs Load Current

85

VIN = 4.2V

80 75 70 65

VOUT = 1.8V L= 2.2uH

60 55 50 0

0.2

0.4

0.6

0.8

1

Load Current (A)

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AS1310 Dual 1.5MHz, 5V/0.8A Sync. Step-down Converter PIN CONFIGURATION TOP VIEW EN1

1

10

SW1

FB1

2

9

GND1

IN2

3

8

IN1

GND2

4

7

FB2

SW2

5

6

EN2

EXPOSED PAD ON BACKSIDE

PIN

SYMBOL

FUNCTION

1, 6

EN1, EN2

Enable Control. Drive EN above 1.5V to turn on the AS1310.Drive EN below 0.3V to turn it off.

2, 7

FB1, FB2

3, 8

IN2, IN1

Supply Input. Bypass to GND with 4.7uF or greater ceramic capacitor

GND2,

Ground

4, 9

Feedback Input. Connect FB to the center point of the external resistor divider. The feedback threshold voltage is 0.6V.

GND1

5,10

SW2, SW1

Power Switch Output. Inductor connection to drains of the internal PFET and NFET switches.

11

EP

Exposed PAD -- Must Connect to Ground。

ORDER INFORMATION

AS1310EPT Packing: T=T/R

Part Number: AS1310

Package: P = TDFN-10L

Operating Temperature: E = -40°C ~ +85°C

AS1310 rev2.6 04/25/2015

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AS1310 Dual 1.5MHz, 5V/0.8A Sync. Step-down Converter BLOCK DIAGRAM IN1 IN2 +

EN1 EN2

IAMP

0.6V VOLTAGE REFERENCE

CURRENT SENSE AMP

-

ICS

0.6V

FB1 FB2

+ -

SLOPE COMP ERROR AMP

+ -

PWM CMP

PWM

DH

MAIN SWITCH PFET

PWM CONTROL LOGIC 1.5MHz OSCILLATOR

SW1 SW2

SYNC. RECTIFIER NFET

DL

GND1 GND2

ABSOLUTE MAXIMUM RATINGS1)

(TA=25°C)

Parameter

Symbol

Supply Voltage Switch Output Enable Voltage Feedback Voltage Switch Peak Current

Rating

VIN VSW VEN VFB IPk θJA θJC TJ TST

Package Thermal Resistance2) Junction Temperature Storage temperature Range

-0.3 to 7 -0.3 to VIN +0.3 -0.3 to VIN -0.3 to VIN 1.5 45 10 125 -65~+150

Unit

V V V V A °C/W °C/W °C °C

RECOMMENDED OPERATING CONDITIONS3) Parameter

Supply voltage Operating Temperature

Symbol VIN TA

Min 2.5 -40

Max 6.0 +85

Unit V °C

NOTEs: 1) Exceeding these ratings may damage the device. 2) Measure on approximately 1’’square of 1 oz copper. 3) The device is not guaranteed to function outside of its operating conditions.

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AS1310 Dual 1.5MHz, 5V/0.8A Sync. Step-down Converter ELECTRICAL CHARACTERISTICS (TA=25°C) VIN = VEN =3.6V, TA = 25°C Unless otherwise noted.

Parameter

Each Converter Supply Current Shutdown Current Osc Frequency

Symbol IQ

Conditions

Active Mode, VEN=VIN, VFB=0.65V

Min

Typ.

Max

-

300

400

Unit uA

ISD fOSC

Shutdown Mode, VFB=0.3V, VIN=4.2V VEN=VIN, ILOAD=400mA

1.2

0.01 1.5

0.1 1.8

MHz

EN Threshold

VEN

VIN=2.5V, VFB=0V

0.3

-

1.5

V

Peak Current

IPEAK VFB

1.00 0.588 0.582 -

1.25 0.600 0.600 -

1.50 0.612 0.618 ±30

A

Feedback Voltage

VIN=3V, VFB=0V TA=25°C -40°C ≤ TA ≤ +85°C VFB = 0.65V

nA

-1.4

-

1.4

%/V

FB Bias Current

V

Line Regulation

RegLINE

VIN = 2.5V to 5.5V, IOUT = 10mA

PFET RDS(ON)

RDS(ON)-P

ISW = 300mA

-

0.35

0.45

NFET RDS(ON)

RDS(ON)-N

ISW = -300mA

-

0.35

0.45

SW Leakage

VEN=0V, VSW=0V or 5V, VIN=5V

-

±0.01

±1

uA

EN Leakage

VEN=0V to 6.5V

-

±0.01

±1

μA

Ω

MARKING INFORMATION

Pin1

1310 1406F

1310: Part Number

F: Internal Code 06: Week (0~52) 14: Year (14=2014,15=2015，...)

AS1310 rev2.6 04/25/2015

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AS1310 Dual 1.5MHz, 5V/0.8A Sync. Step-down Converter TYPICAL PERFORMANCE CHARACTERISTICS

VIN=3.6V, VOUT=1.8V, L=2.2uH, TA=25°C; Unless otherwise noted. Efficiency

Load Regulation

Efficiency vs Load Current

100 95

VIN = 3.6V

85

1.85 1.84

VIN = 4.2V

1.83

80 75

Output Voltage (V)

Efficiency (%)

90

70 65

VOUT = 1.8V L= 2.2uH

60 55 50 0

0.2

Output Voltage vs Load Current

0.4

0.6

0.8

1.82 1.81 1.80 1.79 1.78

VIN = 3.6V L = 2.2uH

1.77 1.76

1

1.75

Load Current (A)

0

0.2

0.4

0.6

0.8

1

Load Current (A)

Line Regulation

1.90

Frequency vs. Supply Volt.

Output Voltage vs Supply Voltage

Oscillator Frequency vs Supply Voltage

1.88

1.90

1.84

Oscillator Frequency (MHz)

Output Voltage (V)

1.86 1.82 1.80 1.78 1.76

IOUT= 0.5A

1.74 1.72

1.80 1.70 1.60 1.50 1.40

IOUT= 0.5A

1.30

1.70 2

3

4

5

6

7

1.20 2

Supply Voltage (V)

3

4

5

6

7

Supply Voltage (V)

AS1310 rev2.6 04/25/2015

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AS1310 Dual 1.5MHz, 5V/0.8A Sync. Step-down Converter TYPICAL PERFORMANCE CHARACTERISTICS (continued)

VIN=3.6V, VOUT=1.8V, L=2.2uH, TA=25°C; Unless otherwise note Output Voltage Ripple (Iout=0A)

Output Voltage Ripple (Iout=0.4A)

Output Voltage Ripple (Iout=0.8A)

Start Up Through VIN

Shutdown Through VIN

Start Up Through EN

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AS1310 Dual 1.5MHz, 5V/0.8A Sync. Step-down Converter TYPICAL PERFORMANCE CHARACTERISTICS (continued)

VIN=3.6V, VOUT=1.8V, L=2.2uH, TA=25°C; Unless otherwise noted. Shutdown Through EN

Transient Response

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AS1310 Dual 1.5MHz, 5V/0.8A Sync. Step-down Converter OPERATION

FUNCTION DESCRIPTION The AS1310 is a dual channel constant frequency current mode PWM step-down converter. The AS1310 is optimized for low voltage, Li-Ion battery powered applications where high efficiency and small size are critical. The AS1310 uses an external resistor divider to set the output voltage from 0.6V to 6.5V. The device integrates both a main switch and a synchronous rectifier, which provides high efficiency and eliminates an external Schottky diode. The AS1310 can achieve 100% duty cycle. The duty cycle D of a step-down converter is defined as: đ??ˇđ??ˇ = đ?‘‡đ?‘‡đ?‘‚đ?‘‚đ?‘‚đ?‘‚ Ă— đ?‘“đ?‘“đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚ Ă— 100% ≈

đ?‘‰đ?‘‰đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚ Ă— 100% đ?‘‰đ?‘‰đ??źđ??źđ??źđ??ź

Where TON is the main switch on time, fosc is the oscillator frequency (1.5MHz), VOUT is the output voltage and VIN is the input voltage.

SHORT CIRCUIT PROTECTION The AS1310 has short circuit protection. When the output is shorted to ground, the oscillator frequency is reduced to prevent the inductor current from increasing beyond the PFET current limit. The PFET current limit is also reduced to lower the short circuit current. The frequency and current limit will return to the normal values once the short circuit condition is removed and the feedback voltage reaches 0.6V. MAXIMUM LOAD CURRENT The AS1310 can operate down to 2.5V input voltage, however the maximum load current decreases at lower input due to large IR drop on the main switch and synchronous rectifier. The slope compensation signal reduces the peak inductor current as a function of the duty cycle to prevent sub-harmonic oscillations at duty cycles greater than 50%. Conversely the current limit increases as the duty cycle decreases.

CURRENT MODE PWM CONTROL Slope compensated current mode PWM control provides stable switching and cycle-by-cycle current limit for excellent load and line response and protection of the internal main switch and synchronous rectifier. The AS1310 switches at a constant frequency (1.5MHz) and regulates the output voltage. During each cycle the PWM comparator modulates the power transferred to the load by changing the inductor peak current based on the feedback error voltage. During normal operation, the main switch is turned on for a certain time to ramp the inductor current at each rising edge of the internal oscillator, and switched off when the peak inductor current is above the error voltage. When the main switch is off, the synchronous rectifier will be turned on immediately and stay on until either the next cycle starts. DROPOUT OPERATION When the input voltage decreases toward the value of the output voltage, the AS1310 allows the main switch to remain on for more than one switching cycle and increases the duty cycle until it reaches 100%. The output Voltage then is the input voltage minus the voltage drop across the main switch and the inductor.

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AS1310 Dual 1.5MHz, 5V/0.8A Sync. Step-down Converter APPLICATION INFORMATION

OUTPUT VOLTAGE SETTING Figure 1 shows the basic application circuit with AS1310 Adjustable output versions. VIN=2.5V ~ 6.5V

C11 4.7uF

R13 100K

OFF ON

VO1=1.8V, 0.8A max C12 10uF

1

EN1

8 IN1

L11 2.2uH

10 R11 300K

2

3 IN2

AS1310

SW1

EN2

GND1 9

C21 4.7uF OFF ON

6 L21 2.2uH

SW2 FB2

FB1

C13 18pF R12 150K

R23 100K

5

VO2=1.2V, 0.8A max C22 10uF

R21 300K

7

GND2 4

C23 R22 18pF 300K

INDUCTOR SELECTION A 2.2ÎźH to 10ÎźH inductor with DC current rating at least 25% higher than the maximum load current is recommended for most applications. For best efficiency, the inductor DC resistance shall be <200mΊ. See Table 2 for recommended inductors and manufacturers. For most designs, the inductance value can be derived from the following equation: đ??żđ??ż =

đ?‘‰đ?‘‰đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚ Ă— (đ?‘‰đ?‘‰đ??źđ??źđ??źđ??ź − đ?‘‰đ?‘‰đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚ ) đ?‘‰đ?‘‰đ??źđ??źđ??źđ??ź Ă— ∆đ??źđ??źđ??żđ??ż Ă— đ?‘“đ?‘“đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚

Where ΔIL is the inductor ripple current. Choose inductor ripple current approximately 30% of the maximum load current.

Figure 1 Adjustable Output Application Circuit In the adjustable version, the output voltage is set by a resistive divider according to the following formula: ��1 �������� = 0.6 × �1 + � ��2 Table1-- Resistor Select for Output Voltage Setting VOUT

R1

R2

1.2V

300KΊ/1%

300KΊ/1%

1.5V

300KΊ/1%

200KΊ/1%

1.8V

300KΊ/1%

150KΊ/1%

2.5V

300KΊ/1%

95.3KΊ/1%

đ??źđ??źđ??żđ??ż = đ??źđ??źđ??żđ??żđ??żđ??żđ??żđ??żđ??żđ??ż +

∆đ??źđ??źđ??żđ??ż 2

Under light load conditions below 100mA, larger inductance is recommended for improved efficiency. Table 3 lists inductors recommended for this purpose.

Table2 -- Suggested Surface Mount Inductors Saturation

Dimensions

Current(A)

L x W x H (mm3)

0.150

1.20

5.4 x 4.2 x 1.8

4.7

0.087

1.14

5x5x2

4.7

0.109

1.15

4.3 x 4.8 x 3.5

Manufacturer

Part Number

Inductance(uH)

Max DCR(Ί)

Coilcraft

D01605T-472

4.7

Toko

D52Lc

Sumida

CR43-4R7

Table3 – Inductors for Imporved Efficiency at 25mA, 50mA, under 100mA Load. Saturation

Manufacturer

Part Number

Inductance(uH)

Max DCR(Ί)

Coilcraft

D01605T-103MX

10

0.3

1.0

0.9

Sumida

LQH4C100K04

10

0.2

1.2

0.8

Sumida

CR43-100

10

0.2

1.0

0.7

Sumida

CR54-100

10

0.1

1.2

1.4

AS1310 rev2.6 04/25/2015

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Current(A)

IRMS(A)

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AS1310 Dual 1.5MHz, 5V/0.8A Sync. Step-down Converter INPUT CAPACITOR SELECTION The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input capacitor impedance at the switching frequency shall be less than input source impedance to prevent high frequency switching current passing to the input. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. For most applications, a 10ÎźF capacitor is sufficient.

PCB BOARD LAYOUT The high current paths (GND1, GND2, IN1, IN2 and SW1, SW2) should be placed very close to the device with short, direct and wide traces. Input capacitor CIN needs to be as close as possible to the IN and GND pins. The external feedback resistors shall be placed next to the FB pin. Keep the switching node SW1, SW2 short and away from the feedback network.

OUTPUT CAPACITOR SELECTION The output capacitor keeps output voltage ripple small and ensures regulation loop stable. The output capacitor impedance shall be low at the switching frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended. The output ripple ΔVOUT is approximately: ∆đ?‘‰đ?‘‰đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚ ≤

đ?‘‰đ?‘‰đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚ Ă— (đ?‘‰đ?‘‰đ??źđ??źđ??źđ??ź − đ?‘‰đ?‘‰đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚ ) đ?‘‰đ?‘‰đ??źđ??źđ??źđ??ź Ă— đ?‘“đ?‘“đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚ Ă— đ??żđ??ż

AS1310 rev2.6 04/25/2015

Ă— ďż˝đ??¸đ??¸đ??¸đ??¸đ??¸đ??¸ +

1 ďż˝ 8đ?‘Ľđ?‘Ľđ?‘“đ?‘“đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚ Ă— đ??śđ??śđ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚đ?‘‚

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AS1310 Dual 1.5MHz, 5V/0.8A Sync. Step-down Converter PACKAGE INFORMATION Package 10-Lead Plastic TDFN-10L

2.95 3.05

Pin1 Identification

2.95 3.05

Note: 1. Dimensions are in millimeters.

TOP VIEW 0.30 0.50 0.18 0.30

Pin1 Identification

10

1 2.20 2.70

0.50BSC 5

6

0.70 0.80

1.40 1.75

0.20BSC SIDE VIEW

BOTTOM VIEW

NOTICE: The information in this document is subject to change without notice. Please contact AniSem for current specifications.Users should warrant and guarantee that third party Intellectual Property rights are not infringed upon when integrating AniSem products into any application. AniSem will not assume any legal responsibility for any said applications. AS1310 rev2.6 04/25/2015

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