TOREX XC9519 User Manual

■

)

XC9519 Series

ETR0710-008

Dual Output Step-Up/Inverting DC/DC Converter

■GENERAL DESCRIPTION

The XC9519 series is a 2 channel (step-up and inverting) DC/DC converter IC. One DC/DC converter is a step-up DC/DC and the other is an inverting DC/DC converter. The step-up converter compares a built-in reference voltage 1.0V to the FBP voltage (accuracy ±1.5%) and a positive output voltage can be set freely with the external components up to 18V. The inverting DC/DC converter compares a difference between a reference voltage and the FBN voltage (accuracy ±1.5%) to the GND, then a negative output voltage can be set until -15V with the external components. With a 1.2MHz frequency, the size of the external components can be reduced. As for operation mode, the device can be selected to use PWM control or automatic PWM/PFM switching control by the MODE pin. In the automatic PWM/PFM switching control mode, control switches from PWM to PFM during light loads. The series is highly efficient from light loads through to large output currents. In the PWM control mode, noise is easily reduced since the frequency is fixed. The control mode can be selected for each application. The soft start and current control functions are internally optimized. During stand-by, all circuits in the IC are shutdown to reduce current consumption to as low as 1.0μA or less. The device includes a gate control pin for the P-channel MOSFET which is used for a load disconnection at the stand-by mode. The GAINP and GAINN pins are used for loop compensation in order to optimize load transient response. With the built-in UVLO (Under Voltage Lock Out) function, the internal driver transistor is forced OFF when input voltage becomes 2.2V or lower.

■APPLICATIONS

●AMOLED

-

Smartphones

-

Tablet PCs

- Automotive navigation systems

●CCD image sensors

-

Surveillance cameras

●e-paper

-e-Books

■TYPICAL APPLICATION CIRCUIT

L

P

P-ch MOS

V

C

IN

IN_SW

BSW

PVIN

AVIN

ENP FBN

ENN

C

IN_A

IN_P

AGND

PGND

SWP

XC9519

GAINP

R

ZP

C

ZP

LXP

SBD

P

GAINN

R

ZN

C

ZN

VOUTP

FBP

VREF

MODE

VOUTN

LXN

C

FBP

R

FBP1

R

SP

R

C

FBN2

L_VR

R

FBP2

R

FBN1

SBD

N

C

LN

L

N

■FEATURES

Input Voltage : 2.7V ~ 5.5V Output Current Positive Output Voltage : Negative Output Voltage :

: 500mA @VIN=3.7V, V

(*1)

4.0V

~ 18.0V (accuracy ±1.5% @25oC)

(*2)

-15.0V

~ -4.0V (accuracy ±1.5% @25oC)

OUTP

=5.0V, V

OUTN

=-5.0V

Oscillation Frequency : 1.2MHz Soft-Start Circuit Built-In : Step-up DC/DC converter 2.5ms (TYP.) :

Inverting DC/DC converter 2.2ms (TYP.) Protection Circuits : Over Current Limit (Integral Latching) Short Protection Latching UVLO Thermal Shutdown Over Voltage Protection Function Addition : Control Pin Load disconnect Pin Phase Compensation Pin Ceramic Capacitor Compatible Operating Ambient Temperature

: -40℃ ~ +85℃

Package : QFN-24 Environmentally Friendly

（*1）V

OUTPSET≧VIN

（*2）V

(V

- V

IN

: Forward voltage of SBDN, V

FN

OUTNSET



+ 0.2V (V

+ V

≦20V

FN

: EU RoHS Compliant, Pb Free

:Positive output voltage range)

OUTPSET

: Nagative output voltage range)

OUTNSET

TYPICAL PERFORMANCE

CHARACTERISTICS

V

=5.0V, V

OUTP

CLP, CLN=4×4.7μF, LP, LN=3.3μH (VLF5014S-3R3M2R0), SBDP, SBDN: CMS03

V

OUTP

C

LP

V

OUTN

P-ch MOS: EMH1303, RZP=7.5kΩ, CZP=4.7nF, RZN=130kΩ, CZN=0.47nF

100

V

="H",V

ENP

80

60

40

3.6V

2.7V

Efficiency:EFFI(%

20

0

0.1 1 10 100 1000

Output Current:I

OUTN

="H"

ENN

VIN= 4.4 V

=-5.0V, I

OUT P

OUTP=IOUTN

PWM/PFM (V PWM (V

MODE

, I

(mA)

OUT N

MODE

="L")

="H")

1/38

XC9519 Series

■BLOCK DIAGRAM

* Diodes inside the circuit are an ESD protection diode and a parasitic diode.

■PRODUCT CLASSIFICATION

●Ordering Information

XC9519①②③④⑤⑥-⑦

Internal ON/OFF Controller

DESIGNATOR

①

②③

④

⑤⑥-⑦

(*1)

The “-G” suffix denotes Halogen and Antimony free as well as being fully RoHS compliant.

(*2)

The XC9519 reels are shipped in a moisture-proof packing.

(*1)

UVLO Detect Voltage A

Oscillation Frequency 12 1.2 MHz

Maximum Current Limit A 2.0A

Package (Order Unit) ZR-G QFN-24 (1,000/Reel)

ITEM SYMBOL DESCRIPTION

UVLO Detect Voltage 2.2V UVLO Hysteresis width 0.2V

2/38

(*2)

■PIN CONFIGURATION

*1

*1: The back metal pad, AGND pin and two PGND pins (No. 21 and 22) should be connected outside.

■PIN ASSIGNMENT

XC9519

Series

PIN NUMBER

QFN-24

1, 2

3

4, 5

6

7 8

9

10

11

12

13

14

15

16

17

18, 19

20

21, 22

23

24

PIN NAME FUNCTION

PVIN

NC No Connection

LXN Switching of Inverting DC/DC Converter

VOUTN

MODE Selection Pin for Control Mode

VREF Reference Output Voltage

AVIN Power Supply Input 2

FBN Feedback Pin for Inverting DC/DC Converter

GAINN Loop Compensation Pin for Inverting DC/DC Converter

AGND Analog Ground

GAINP Loop Compensation Pin for Step-Up DC/DC Converter

FBP Feedback Pin for Step-Up DC/DC Converter

ENP Chip Enable Pin for Step-Up DC/DC Converter

BSW P-channel MOS FET Gate Control Pin

VOUTP Output Voltage Sense for Step-Up DC/DC Converter

LXP Switching Output of Step-Up DC/DC Converter

NC No Connection

PGND Power Ground

ENN Chip Enable Pin for Inverting DC/DC Converter

SWP Detect Monitoring Voltage Pin for P-channel MOS FET Drain

Power Supply Input 1

Detect Monitoring of Inverting DC/DC Output Voltage

3/38

XC9519 Series

■FUNCTION

1. ENP Pin Function

ENP PIN STATUS



H Step-up DC/DC Converter Active

L Step-up DC/DC Converter Stand-by

* Please do not leave the ENP pin open.

V

IN

ENP

0V

V

IN

BSW

0V

2.5ms

V

OUTP

V

IN

0V

2. ENN Pin Function

ENN PIN STATUS

H Inverting DC/DC Converter Active

L Inverting DC/DC Converter Stand-by

* Please do not leave the ENP pin open.

V

IN

ENN

0V

V

OUTN

3. MODE Pin Function

MODE PIN STATUS

H Auto PWM/PFM

L PWM Control

* Please do not leave the MODE pin open.

2.2ms

4/38

■ABSOLUTE MAXIMUM RATINGS

PAR AMETER SYMBOL RATINGS UNITS

PVIN Pin Voltage V AVIN Pin Voltage V

ENP Pin Voltage V ENN Pin Voltage V

MODE Pin Voltage V

LXP Pin Voltage V LXN Pin Voltage V FBP Pin Voltage V FBN Pin Voltage V

VOUTP Pin Voltage V VOUTN Pin Voltage V

BSW Pin Voltage V SWP Pin Voltage V

VREF Pin Voltage V

GAINP Pin Voltage V

GAINN Pin Voltage V

LXP Pin Current I LXN Pin Current I

Power Dissipation Pd 1500 (PCB mounted) * mW

Operating Ambient Temperature Topr -40 ~ +85

Storage Temperature Tstg -55 ~ +125

* All voltages are described based on the AGND and PGND pin.

* The value is an example of data which is taken with the PCB mounted. Please refer to our web site for details.

XC9519

Series

Ta =2 5 ℃

-0.3 ~ +6.0 V

PVIN

-0.3 ~ +6.0 V

AVI N

-0.3 ~ +6.0 V

ENP

-0.3 ~ +6.0 V

ENN

-0.3 ~ +6.0 V

MODE

-0.3 ~ +22.0 V

LXP

V

LXN

-0.3 ~ +6.0 V

FBP

-0.3 ~ +6.0 V

FBN

-0.3 ~ +22.0 V

OUTP

V

OUTN

-0.3 ~ +6.0 V

BSW

-0.3 ~ +6.0 V

SWP

-0.3 ~ +6.0 V

REF

-0.3 ~ +6.0 V

GAINP

-0.3 ~ +6.0 V

GAINN

4000 mA

LXP

4000 mA

LXN

-22.0 ~ V

PVIN

-22.0 ~ V

AVI N

+0.3 V

PVIN

+0.3 V

AVI N

o

C

o

C

5/38

OSC

XC9519 Series

■ELECTRICAL CHARACTERISTICS

●XC9519 Series, Common Characteristics

PARAMETER SYMBOL CONDITIONS

2.7 - 5.5 V -

V

UVLO

IN

V

ENP

The voltage which L V

is decreasing from 2.4V.

IN

=1.5V , V

= V

ENN

= 0V, V

FBP

stops oscillation while

XP

Input Voltage

UVLO Detect Voltage

f

=1.2MHz

(*1)

MIN. TYP. MAX. UNITS CIRCUIT

= 0.1V

FBN

Ta=25℃

2.0 2.2 2.4 V ⑨

UVLO Release Voltage

UVLO Hysteresis Range

Supply Current 1

Supply Current 2

Supply Current 3

Stand-by Current

ENP ”H” Voltage

ENP ”L” Voltage

ENP ”H” Current

ENP ”L” Current

ENN ”H” Voltage

ENN ”L” Voltage

ENN ”H” Current

ENN ”L” Current

MODE ”H” Voltage

MODE ”L” Voltage

MODE ”H” Current

MODE ”L” Current

FBP ”H” Current I

FBP ”L” Current I

FBN ”H” Current I

FBN ”L” Current I

SWP ”H” Current I

SWP ”L” Current I

Integral Latch Time

V

UVLOR

V

UVLOH

I

DD1

I

DD2

I

DD3

V

I

STB

V

ENPH

V

ENPL

VIN = V

I

ENPH

VIN = V

I

ENPL

V

ENNH

V

ENNL

VIN = V

I

ENNH

I

VIN = V

ENNL

V

MODEH

V

MODEL

I

VIN = V

MODEH

VIN = V

I

MODEL

VIN =5.5V, V

FBPH

VIN =5.5V, V

FBPL

VIN =5.5V, V

FBNH

VIN =5.5V, V

FBNL

VIN =5.5V, V

SWPH

VIN =5.5V, V

SWPL

t

LAT

=1.5V , V

V

ENP

The voltage which L V

is increasing from V

IN

= V

UVLOH

V

=V

IN

ENP

V

=5.5V, V

FBP

V

= V

IN

ENN

V

= -0.1V

FBN

V

=V

IN

ENP

V

= 5.5V, V

FBP

=5.5V, V

IN

= 5.5V, V

V

IN

The voltage which L V

is increasing from 0.3V.

ENP

= 5.5V, V

V

IN

The voltage which L

Is decreasing from 1.4V.

V

ENP

= 5.5V, V

V

IN

The voltage which L V

is increasing from 0.3V.

ENN

= 5.5V, V

V

IN

The voltage which L V

is decreasing from 1.4V.

ENN

= V

V

IN

ENP

The voltage which supply current decreases while V

MODE

= V

V

IN

ENP

The voltage which supply current increases while V

is decreasing from 1.4V.

MODE

V

=V

IN

ENP =VENN

V

=0.9V, V

FBP

Time to stop operation from the start of maximum

= V

ENN

UVLOR

= V

ENN

FBN

= V

MODE

= V

MODE

OUTP

ENP =VENN

ENN

= 0V, V

FBP

starts oscillation while

XP

UVLO

- V

- 0.2 - V -

UVLO

= V

= 5.5V

MODE

= -0.1V, V

= 5.5V, V

= V

= 5.5V

SWP

= V

MODE

= V

= 0V, V

MODE

starts oscillation while

XP

= V

= 0V, V

MODE

stops oscillation while

XP

= 0.1V

FBN

2.2 2.4 2.6 V ⑨

.

OUTP

ENP

ENN

= V

= 0V

=0V

SWP

= 5.5V

50 170 450 μA ①

30 90 250 μA ①

30 110 250 μA ①

= 0V - 0 1.0 μA ①

= 0V

FBP

1.4 - 5.5 V ⑦

= 0V

FBP

AGND - 0.3 V ⑦

= 5.5V -0.1 - 0.1 μA ⑦ = 0V -0.1 - 0.1 μA ⑦

= V

ENP

= 0V, V

MODE

starts oscillation while

XN

= V

= 0V, V

MODE

stops oscillation while

XN

FBN

= 5.5V

1.4 - 5.5 V ⑦

= 5.5V

AGND - 0.3 V ⑦

= 5.5V -0.1 - 0.1 μA ⑦ = 0V -0.1 - 0.1 μA ⑦

= 5.5V, V

ENN

= 0V,

1.4 - 5.5 V ⑦

is increasing from 0.3V.

= 5.5V, V

ENN

= 0V,

AGND - 0.3 V ⑦

= 5.5V -0.1 - 0.1 μA ⑦

= 0V -0.1 - 0.1 μA ⑦

=V

ENP =VENN

= 5.5V, V

= 0.1V

FBN

=V =V =V =V =V

MODE

=0V, V =0V, V =0V, V =0V, V =0V, V =0V, V

=0V

=5.5V

FBP

=0V -0.1 - 0.1 μA ⑦

FBP

=5.5V

FBN

=0V -0.1 - 0.1 μA ⑦

FBN

=5.5V

SWP

=0V -0.1 - 0.1 μA ⑦

SWP

-0.1 - 0.1 μA ⑦

1.0 2.0 3.0 ms ⑤

current limit status.

Thermal Shutdown

Temperature

Thermal Shutdown

Release Temperature

Thermal Shutdown

Hysteresis Range

- 150 - oC -

T

TSD

- 130 - oC

T

TSDR

T

HYS

=T

TSDR

- T

- 20 -

TSD

(*1) If the applied voltage and its pin name are not stated, those pins are left open for measurement.

o

C -

-

6/38

■ELECTRICAL CHARACTERISTICS (Continued)

●XC9519 Series, Step-up DC/DC Converter

PARAMETER SYMBOL CONDITIONS

V

Output Voltage Range

FBP Voltage

Oscillation Frequency

PFM Switching Current

Maximum Duty Cycle

LXP SW “H” ON

Resistance

LXP SW “H” Leak

Current

Maximum Current Limit

FBP Voltage

Temperature

(*3)

(V

OUTPSET

V

FBP

f

OSCP

VIN =V

I

PFMP

D

MAXP

VIN = V

R

LXPH

VIN =5.5V, V

I

LEAKH

I

LIMP



V

/

FBP

・



Topr)

FBP

V

= V

= 3.6V, V

IN

ENP

V

= V

SWP

= 3.6V

OUTP

The voltage which L

is decreasing.

V

FBP

V

= V

= 3.6V, V

IN

ENP

V

= V

SWP

= V

ENP

= 3.6V, V

ENP

= V

SWP

= 3.6V, V

ENP

= 5.5V, V

ENP

= 0.9V, V

= 3.6V, V

MODE

= 3.6V, V

=0V, V

ENP

OUTP

V V

OUTP

= V

IN

OUTP

=V

IN

FBP

-40 oC≦Topr≦85 oC - ±100 - ppm /

Characteristics

V

= 3.6V, V

Soft-Start Time

IN

V

t

SSP

OUTP

Time to start L

= V

ENN

= 3.6V, V

SWP

XP

(0V→3.6V) V

=V

= 5.5V, V

IN

Short Protection

Threshold Voltage

V

SHORTP

ENP

V

= V

SWP

= 5.5V

OUTP

The voltage which the integral latch time becomes 200μs or less while V V

= V

= 3.6V, V

IN

ENP

V

= V

Over Voltage

Protection Limit

BSW Pin Current

CL Discharge Resistance

V

R

OVPP

I

BSW

DCHGP

OUTP

The voltage which L V

FBP

V

IN

V

OUTP

V

IN

V

OUTP

= V

= 6.0V, V

= 3.6V, V

SWP

is increasing.

= 3.6V, V

ENP

= V

= 3.6V, V

SWP

ENP =VENN

= 4.0V

ENN

XP

ENN

= 3.6V, V

ENN

LXP

ENN

= V

SWP

= V

MODE

oscillation from the rise of V

ENN

XP

ENN

(*1)

MIN. TYP. MAX. UNITS CIRCUIT

= V

= 0V

MODE

starts oscillation while

= V

= 0V

MODE

=0V

FBP

=0V 180 350 550 mA ⑧

ENN

= V

= 0V

MODE

=0V

FBP

= V

MODE

= 0V, I

= 100mA - 0.12 0.28 Ω ④

LXP

=5.5V - 0.01 1.0 μA ⑥

= V

=0V

MODE

= 5.5V

= 0V

= 0.95V

FBP

= V

GAINP

MODE

= 3.6V

=0V

is decreasing.

FBP

= 0V

ENP

.

stops oscillation while

= V

= 0V

MODE

=3.6V

BSW

= V

= 0V

MODE

XC9519

Series

Ta=25℃

(*2)

4.0

0.985 1.000 1.015 V ③

1020 1200 1380 kHz ③

84 90 97 % ③

2000 - 4000 mA ⑤

0.8 2.5 5.2 ms ③

0.3 0.5 0.7 V ⑤

V

FBP

+0.03

0.2 1.2 3.0 mA ⑦

50 200 500 Ω ②

- 18.0 V -

o

C-

V

+0.07

FBP

V

FBP

+0.10

V ③

NOTE: (*1) If the applied voltage and its pin name are not stated, those pins are left open for measurement.

(*2) Input voltage or positive output voltage range should be V

OUTPSET≧VIN

+ 0.2V.

(*3) Maximum current limit denotes the level of detection at peak of coil current.

7/38

XC9519 Series

■ELECTRICAL CHARACTERISTICS (Continued)

●XC9519 Series, Inverting DC/DC Converter

PARAMETER SYMBOL CONDITIONS

-15.0

(*3)

V

OUTNSET

= V

V

FBN

The voltage which L

V

REF

V

OUTNA

V

f

OSCN

VIN = V

I

PFMN

V

D

MAXN

VIN = V

R

LXNL

V

I

LEAKL

V

I

LIMN



V

REF

(V

・



REF

V

/

-40 oC≦Topr≦85 oC - ±100 - ppm /

To pr )

= 3.6V, V

IN

ENN

is increasing.

FBN

= V

= 3.6V, V

IN

ENN

=V

ENN

= 0.1V

-V

REF

= 3.6V, V

= V

= 3.6V, V

= 5.5V, V

OUTNA

= V

IN

= V

IN

= V

IN

= V

IN

FBN

ENP

XN

ENP

0.985 1.000 1.015 V -

FBN

ENP

= 3.6V, V

MODE

ENP

Output Voltage Range

FBN Voltage

Reference Voltage

Output Voltage Accuracy

Oscillation Frequency

PFM Switching Current

Maximum Duty Cycle

LXN SW “L” ON

Resistance

LXN SW “L” Leak

Current

Maximum Current Limit

Reference Voltage

Temperature

Characteristics

Soft-Start Time

t

SSN

= 3.6V, V

V

IN

Time to start L

= V

ENP

MODE

oscillation from the rise of V

XN

(0V→3.6V)

= V

Short Protection

Threshold Voltage

Over Voltage

Protection Limit

CL Discharge Resistance

V

SHORTN

V

R

DCHGN

OVPN

V

IN

The voltage which the integral latch time becomes 200μs or less while V

V

IN

The voltage which L V

FBN

V

IN

V

OUTN

= 5.5V, V

ENN

= V

= 3.6V, V

ENN

is decreasing.

= 6.0V, V

ENP =VENN

= -4.0V

ENP

XN

NOTE: (*1) If the applied voltage and its pin name are not stated, those pins are left open for measurement.

(*2) Input voltage or positive output voltage range should be V

(*3) Maximum current limit denotes the level of detection at peak of coil current.

IN

8/38

(*1)

MIN. TYP. MAX. UNITS CIRCUIT

= V

= 0V

MODE

starts oscillation while

= V

= 0V, V

MODE

= V

= 0V, V

MODE

= 0V 220 350 550 mA ⑧

ENP

= V

= 0V, V

MODE

= V

= 0V, I

MODE

= V

= 0V, V

MODE

= V

= 0V

MODE

= 0V, V

FBN

= V

= 0V

MODE

FBN

= V

= 0V, V

MODE

= 0.1V 0.970 1.000 1.030 V ①

FBN

= 0.1V 1020 1200 1380 kHz ③

FBN

= 0.1V 84 90 97 % ③

FBN

= 100mA - 0.22 0.48 Ω ④

LXN

= 0.1V - 0.01 1.0 μA ⑥

FBN

= 0.05V

is increasing.

GAINN

stops oscillation while

= V

= 0V

MODE

- V

+ VFN≦20V (VFN: Forward voltage of external schottky barrier diode) .

OUTNSET

ENP

= 3.6V

2000 - 4000 mA ⑤

.

V

-0.10

Ta=25℃

(*2)

- -4.0 V -

-26 0 26 mV ③

o

C -

0.8 2.2 4.0 ms ③

0.3 0.5 0.7 V ⑤

FBN

V

-0.07

FBN

V

FBN

-0.03

V ③

50 200 500 Ω ②

XC9519

Series

■OPERATIONAL EXPLANATION

The XC9519 series consists of a reference voltage source, ramp wave circuit, error amplifier, PWM comparator, phase compensation circuit,

driver transistor, current limiter circuit, short protection circuit, UVLO circuit, thermal shutdown circuit, over voltage protection, load disconnect

control and others. (See the block diagram below.)

By using the error amplifier, the FBP (FBN) pin voltage is compared with the internal reference voltage. The error amplifier output is sent to the

PWM comparator in order to determine the duty cycle of PWM switching. The signal from the error amplifier is compared with the ramp wave from

the ramp wave circuit, and the resulting output is delivered to the buffer driver circuit to provide on-time of the duty cycle at the LXP (LXN) pin.

This process is continuously performed to ensure stable output voltage.

The current feedback circuit monitors the driver transistor current for each switching operation, and modulates the error amplifier output signal

to provide multiple feedback signals. This enables a stable feedback loop even when using a low ESR capacitor such as ceramic, which results in

ensuring stable output voltage.

* Diodes inside the circuit are an ESD protection diode and a parasitic diode.

Internal ON/OFF Controller

9/38

XC9519 Series

■OPERATIONAL EXPLANATION (Continued)

The reference voltage source provides the reference voltage to ensure stable output voltage of the DC/DC converter.

<Step-up DC/DC Converter Error Amplifier>

The step-up DC/DC converter error amplifier is an amplifier for output voltage monitoring. The FBP pin voltage is compared to the reference

voltage. When a voltage lower than the reference voltage is feedback to the FBP pin voltage, the output voltage of the error amplifier goes high.

External compensation of the error amplifier frequency characteristic is also possible.

<Inverting DC/DC Converter Error Amplifier> The inverting DC/DC converter error amplifier is an amplifier for output voltage monitoring. The FBN pin voltage is compared to GND. When a

voltage higher than GND is feedback to the FBN pin voltage, the output voltage of the error amplifier goes high. External compensation of the

error amplifier frequency characteristic is also possible.

The ramp wave circuit determines switching frequency. The frequency is fixed 1.2MHz internally. Clock pulses generated in this circuit are

used to produce ramp waveforms needed for PWM operation, and to synchronize all the internal circuits.

When the AVIN pin voltage becomes 2.2V or lower, the driver transistor is forced OFF to prevent false pulse output caused by unstable

operation of the internal circuitry. When the AVIN pin voltage becomes 2.4V or higher, switching operation takes place. By releasing the UVLO

function, the IC performs the soft start function to initiate output startup operation. The soft start function operates even when the AVIN pin

voltage falls momentarily below the UVLO detect voltage. The UVLO circuit does not cause a complete shutdown of the IC, but causes pulse

output to be suspended; therefore, the internal circuitry remains in operation.

For protection against heat damage of the ICs, thermal shutdown function monitors chip temperature. The thermal shutdown circuit starts

operating and the driver transistor will be turned off when the chip’s temperature reaches 150

after shutting of the current flow, the IC performs the soft start function to initiate output startup operation.

o

C. When the temperature drops to 130 oC or less

, I

In PFM control operation, until coil current reaches to a specified level (I

) that the driver transistor is kept on can be given by the following formula.

(t

ON

t

ON

= L ×I

PFMP

(I

PFMN

) / V

IN

PFMP

), the IC keeps the driver transistor on. In this case, time

PFMN

< PFM Duty Limit >

In PFM control operation, the maximum duty cycle (DTY

(e.g. the condition that the step-up ratio is large), it’s possible for the driver transistor to be turned off even when the coil current doesn’t reach to I

(I

).

PFMN

) is set to 50% (TYP.). Therefore, under the condition that the duty increases

LIMIT_PFM

PFMP

10/38

XC9519

Series

■OPERATIONAL EXPLANATION (Continued)

< CL Auto-Discharge Function >

This function enables high-speed discharge of the charge on the output capacitor (C

means of the internal switch between the VOUTP pin and AGND pin (between the VOUTN pin and AVIN pin).

This function makes it possible to prevent malfunctioning of applications caused by charge remaining on C The discharge time is determined by the C

discharge resistance (R

L

) and CL. Ifτ(τ= CL × R

DCHC

equation for the output voltage discharge time can be obtained from the following CR discharge equation.

ｔ=τln（

V

OUTSET

/ V）

V: Output voltage during discharge

V

: Output voltage

OUTSET

t: Discharge τ: C

L×RDCHG

time

[Example]

When the set voltage (V

discharge time t from the start of C

ｔ=τ

ln ( V

(*1) Calculated with I

OUTPSET

/ V )= CLP×R

= 0mA

OUT

)=5.0V, CLP=18.8μF, and the CL discharge resistance (R

OUTPSET

high-speed discharge until the output voltage falls to 1.0V can be calculated as follows:

L

DCHGP

ln ( V

/ V ) = 18.8μF×200Ω×ln ( 5.0V / 1.0V ) = 6.05×10-3 s = 6.05 ms

OUTPSET

The step-up DC/DC Converter and the Inverting DC/DC Converter are switching synchronously based on one internal clock. The phase of

the step-up driver on timing for the DC/DC Converter is shifted to completely opposite position (180 degrees different) upon the phase of driver on timing for the Inverting DC/DC Converter.

) when an L level signal is input to the ENP (ENN) pin by

L

.

L

) is the time constant of CL and R

DCHG

)=200Ω (TYP.) of the DC/DC Converter, the

DCHGP

(*1)

DCHG

, the

Internal OSC

Inductor Peak Current

1.2MHz

Boost_I

LX

Inverting_I

<Overvoltage Protection> Overvoltage protection monitors the output voltage V (V

) from rising too far above the set voltage. In particular, fluctuations in the load cause the output voltage to rise, and when the FBP (FBN)

OUTN

pin voltage reaches the overvoltage protection detection voltage, the driver transistor of the step-up DC/DC converter (inverting DC/DC converter) is turned off to hold down the rise of output voltage. When the output voltage falls after overvoltage protection detection, normal DC/DC converter operation resumes. The output voltage V

V

OUT_OVP P (VOUT_OVPN

V

OUTPSET (VOUTNSET

[Example]

In a step-up DC/DC converter with the indicated conditions, the output voltage V

calculated as shown below.

Condition: Output Voltage (V V

OUT_OVPP

<Load disconnect Control Circuit> The Load disconnect control circuit makes it possible to break continuity between V step-up DC/DC converter is in the standby state.

0A

LX

0A

OUT_OVP

)=V

OUTPSET (VOUTNSET

): Output voltage, V

= V

OUTPSET

× V

Inductor Peak Current

(V

OUTP

that is detected by overvoltage protection is obtained from the following equation:

) × V

OVP P (VOVPN

OVPP(VOVPN

OUTPSET

= 5.0V × (1.0 + 0.07(TYP.)) =5.0V × 1.07 = 5.35V

OVP

): Detect Overvoltage Protection Voltage

)=5.0V, V

OVPP=VFBP

) using the FBP (FBN) pin voltage, and prevents the output voltage V

OUTN

)

that is detected by overvoltage protection can be

OUT_OVPP

+0.07V(TYP.) , V

=1.0V(TYP.)

FBP

and V

IN

by turning off the external P-ch MOS FET when the

OUTP

11/38

XC9519 Series

■OPERATIONAL EXPLANATION (Continued)

The current limiter circuit of the XC9519 series monitors the current flowing through the driver transistor, and features a combination of the

current limit mode and the operation suspension mode. ① When the driver current is greater than a specific level, the current limit function operates to turn off the pulses from the LXP (LXN) pin at any

given timing.

② When the driver transistor is turned off, the limiter circuit is then released from the current limit detection state. ③ At the next pulse, the driver transistor is turned on. However, the transistor is immediately turned off in the case of an over current state. ④ When the over current state is eliminated, the IC resumes its normal operation.

The IC waits for the over current state to end by repeating the steps ① through ③. If an over current state continues for the integral latch time

and the above three steps are repeatedly performed, the IC performs the function of integral latching the OFF state of the driver transistor, and

goes into operation suspension mode.

Once the IC is in suspension mode, operations can be resumed by either turning the IC off via the ENP (ENN) pin, or by restoring power. Care

must be taken when laying out the PC Board, in order to prevent misoperation of the current limit mode. Depending on the state of the PC Board,

latch time may become longer and latch operation may not work. In order to avoid the effect of noise, the board should be laid out so that input

capacitors are placed as close to the IC as possible.

(a) Step-up DC/DC Converter

I

OUTP

V

OUTP

V

LXP

ENP

(b) Inverting DC/DC Converter

I

OUTN

Limit < 2.0ms(TYP.)

Limit > 2.0ms(TYP.)

Current Limit Level

Restart

Current Limit Level

0mA

AGND,PGND

0mA

V

ENN

OUTN

LXN

Restart

AGND,PGND

<Short-Circuit Protection>

The short-circuit protection circuit monitors the output voltage from the V

OUTP (VOUTN

). In case where output is accidentally shorted to the GND

and when the FBP voltage decreases less than short protection threshold voltage or FBN pin voltage becomes larger than short protection

threshold voltage and a current more than the I

flows to the driver transistor, the short-circuit protection quickly operates to turn off and to latch

LIM

the driver transistor.

Once the IC is in suspension mode, operations can be resumed by either turning the IC off via the ENP (ENN) pin, or by restoring power.

12/38

TOREX XC9519 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual