IS31BL3231

IS31BL3231
FLASH LED DRIVER
July 2015
GENERAL DESCRIPTION
FEATURES
The IS31BL3231 is a current-regulated charge pump
and ideal for powering high brightness LEDs for camera
flash and torch applications. The charge pump can be
set to regulate two current levels for FLASH and TORCH
modes. The IS31BL3231 automatically switches
between linear and boost modes ensuring that LED
current does not depend on the LED forward voltage.
IS31BL3231 provides low cost, space saving solution for
driving LED. It also integrates thermal and short circuit
protection function.
IS31BL3231 is available in DFN-10 (3mm × 3mm). It
operates from 2.7V to 5.5V over the temperature range
of -40°C to +85°C.
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Operates from 2.7V to 5.5V
Up to 90% efficiency in Torch Mode
Output current up to 750mA
Adjustable output current in Flash Mode
Minimum external components, no external
inductor required
Automatic boost mode
Less than 1µA shutdown current
Low ripple and EMI
Over voltage protection on output
Short and over temperature protections
Available in DFN-10 (3mm × 3mm) package
APPLICATIONS
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White LED backlighting
Cellular phones
Generic lighting/flash/strobe applications
TYPICAL APPLICATION CIRCUIT
Figure 1
Typical Application Circuit (Torch Mode Lv1-227mA, Flash Mode 718mA)
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Rev. C, 06/12/2015
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IS31BL3231
Figure 2
Typical Application Circuit (Torch Mode Lv1-50mA, Flash Mode 518mA)
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Rev. C, 06/12/2015
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IS31BL3231
PIN CONFIGURATION
Package
Pin Configuration (Top View)
DFN-10
PIN DESCRIPTION
No.
Pin
Description
1
VCC
Power supply.
2
CP
Positive input for external flying cap.
3
CN
Negative input for external flying cap.
4
FLASH
Input pin to toggle operation between Flash Mode and
Torch Mode.
5
EN
Shutdown control input and Torch reference select pin.
The intensity can be modulated by PWM signal via EN
pin. It is recommended to use 100Hz and 5%~95% duty
cycle PWM signal.
6
RSET
7
FB
8
SGND
Internal ground pin.
9
PGND
Power ground pin.
10
VOUT
Charge pump output voltage.
Thermal Pad
Connect to GND.
Set the FB voltage in Flash Mode.
V FB  1.25V / RSET   11 .2 k
Feedback input for the current control loop.
I LED  VFB / RFB
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IS31BL3231
ORDERING INFORMATION
Industrial Range: -40°C to +85°C
Order Part No.
Package
QTY/Reel
IS31BL3231-DLS2-TR
DFN-10, Lead-free
2500
Copyright © 2015 Integrated Silicon Solution, Inc. All rights reserved. ISSI reserves the right to make changes to this specification and its products at any time without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and before placing orders for products. Integrated Silicon Solution, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless Integrated Silicon Solution, Inc. receives written assurance to its satisfaction, that: a.) the risk of injury or damage has been minimized; b.) the user assume all such risks; and c.) potential liability of Integrated Silicon Solution, Inc is adequately protected under the circumstances
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Rev. C, 06/12/2015
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IS31BL3231
ABSOLUTE MAXIMUM RATINGS
Supply voltage, VCC
Voltage at EN pin
Output current pulse (Flash Mode)
Output current pulse (Torch Mode)
Maximum junction temperature, TJMAX
Storage temperature range, TSTG
Operating temperature range, TA
ESD (HBM)
ESD (CDM)
-0.3V ~ +6.0V
0V ~ 7V
1A
0.4A
150°C
-65°C ~ +150°C
−40°C ~ +85°C
7kV
1kV
Note:
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only and
functional operation of the device at these or any other condition beyond those indicated in the operational sections of the specifications is not
implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
DC CHARACTERISTICS
TA = +25°C, VCC = 2.7V ~ 5.5V, unless otherwise stated. Typical value are TA = +25°C, VCC = 4.2V.
Symbol
Parameter
Condition
VCC
Supply voltage
ICC
Quiescent current
VCC = 4.2V，VFLASH = 0V
ISD
Shutdown current
VCC = 5.5V，VEN = 0V
tON
Charge pump soft start time
VFB
FB reference voltage
VFB_MAX
TOVP
Min.
Typ.
2.7
Max. Unit
5.5
0.6
mA
1
550
VFLASH = VCC，RSET = 88.7kΩ
150
VFLASH = 0V
50
Maximum FB reference voltage (Note 1)
µA
µs
mV
550
Over temperature protection
V
mV
160
°C
VIH
Input logic high
1.4
V
VIL
Input logic low
tLO
EN low time
(Note 1)
tHI
EN high time
(Note 1)
tOFF
EN shutdown timeout
(Note 1)
500
µs
tLAT
EN latch timeout
(Note 1)
500
µs
0.4
V
0.3
75
µs
0.1
75
µs
Note 1: Guaranteed by design.
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Rev. C, 06/12/2015
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IS31BL3231
TYPICAL PERFORMANCE CHARACTERISTICS
250
800
Flash Mode
ILED = 700mA
VOUT = 3.73V
700
Output Current(mA)
Output Current(mA)
200
150
100
600
500
400
300
200
50
Torch Mode
ILED = 200mA
VOUT = 3.45V
0
3
100
3. 2
3. 4
3. 6
3. 8
4
0
4. 2
3
3. 2
3. 4
Supply Voltage(V)
Figure 3
EN Pin
5V/Div
Supply Voltage vs. Output Current (Torch Mode)
VCC = 3.6V
Torch Mode
ILED = 200mA
RFB = 0.22Ω
3. 6
3. 8
4
4. 2
Supply Voltage(V)
Figure 4
EN Pin
5V/Div
Supply Voltage vs. Output Current (Flash Mode)
VCC = 3.6V
Flash Mode
ILED = 700mA
VOUT
1V/Div
VOUT
1V/Div
IIN
500mA/Div
IIN
500mA/Div
Time (200µs/Div)
Figure 5
Time (200µs/Div)
EN On (Torch Mode)
Figure 6
EN On (Flash Mode)
FLASH Pin VCC = 3.6V
Torch Mode to Flash Mode
5V/Div
FLASH Pin VCC = 4.2V
Torch Mode to Flash Mode
5V/Div
VOUT
1V/Div
VOUT
1V/Div
VFB
0.2mA/Div
VFB
0.2mA/Div
IOUT
1A/Div
IOUT
1A/Div
Time (50µs/Div)
Figure 7
Torch Mode to Flash Mode
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Rev. C, 06/12/2015
Time (50µs/Div)
Figure 8
Torch Mode to Flash Mode
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IS31BL3231
100
100
Flash Mode
ILED = 700mA
Torch Mode
ILED = 200mA
80
Efficiency(%）
Efficiency(%）
80
60
40
20
0
60
40
20
3
3. 2
3. 4
3. 6
3. 8
4
4. 2
0
3
3. 2
Supply Voltage(V)
Figure 9
Supply Voltage vs. Efficiency (Torch Mode)
Integrated Silicon Solution, Inc. – www.issi.com
Rev. C, 06/12/2015
3. 4
3. 6
3. 8
4
4. 2
Supply Voltage(V)
Figure 10
Supply Voltage vs. Efficiency (Flash Mode)
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IS31BL3231
FUNCTIONAL BLOCK DIAGRAM
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Rev. C, 06/12/2015
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IS31BL3231
APPLICATION INFORMATION
GENERAL DESCRIPTION
TORCH MODE
The IS31BL3231 is a current-regulated charge pump
and ideal for powering high brightness LEDs for
camera flash and torch applications.
By pulling the FLASH pin to low, IS31BL3231 operates
in the Torch Mode. The VFB is controlled by Pulse
Count Control (PCC wire) serial interface. The
interface records rising edges of the EN pin and
decodes them into 8 different states. The 8 voltage
level settings available are indicated in Table 1.
CHARGE PUMP
The charge pump converter boosts input supply
voltage (VCC) up to a higher output voltage (VOUT) to
drive LED.
The charge pump converter only requires three
external components: supply decoupling capacitor,
output bypass capacitor and flying capacitor.
Table 1 VFB Control
Pulse
VFB (Typ.)
1
ILED (Typ.)
RFB = 0.22Ω
RFB = 1Ω
50mV
227mA
50mA
2
60mV
273mA
60mA
3
70mV
318mA
70mA
4
85mV
386mA
85mA
5
100mV
455mA
100mA
CURRENT SETTING
6
120mV
545mA
120mA
The LED current is set by the external resister, RFB,
following the Equation (1) below.
7
140mV
636mA
140mA
≥8
170mV
773mA
170mA
Choose low ESR capacitors to ensure the best
operating performance and place the capacitors as
close as possible to the IS31BL3231.
The charge pump will start up automatically to offer a
higher output voltage when VFB is lower than the
setting value.
I LED  VFB / RFB
(1)
VFB is calculated by the Equation (2) when
IS31BL3231 operates in the Flash Mode. VFB is set in
the Table 1 when IS31BL3231 operates in the Torch
Mode.
OPERATING MODE
TIMING CONTROL
The EN pin should be configured as the Figure 11. tLAT
is the latch time. High level should be at last tLAT to
active the pulse signal. tOFF is the shutdown time. EN
pin is pulled low at last tOFF the IC will be shutdown.
FLASH MODE
By pulling the FLASH pin to high, IS31BL3231
operates in the Flash Mode. VFB is set by the RSET.
V FB  1.25V / RSET   11 .2 k
(2)
For example, in Figure 1,
RFB = 0.22Ω, RSET = 88.7kΩ,
So, VFB  1.25V / 88 .7 k   11 .2 k  158 mV
I LED  158mV / 0.22  718mA
The maximum VFB shouldn’t be over 550mV or the
actual current will be large difference from then
calculated current.
Integrated Silicon Solution, Inc. – www.issi.com
Rev. C, 06/12/2015
Figure 11
EN pin timing
THERMAL PROTECTION
The IS31BL3231 has a thermal protection circuit that
will shut down the chip if the die temperature rises
above the thermal limit until the temperature falls
down.
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IS31BL3231
CLASSIFICATION REFLOW PROFILES
Profile Feature
Pb-Free Assembly
Preheat & Soak
Temperature min (Tsmin)
Temperature max (Tsmax)
Time (Tsmin to Tsmax) (ts)
150°C
200°C
60-120 seconds
Average ramp-up rate (Tsmax to Tp)
3°C/second max.
Liquidous temperature (TL)
Time at liquidous (tL)
217°C
60-150 seconds
Peak package body temperature (Tp)*
Max 260°C
Time (tp)** within 5°C of the specified
classification temperature (Tc)
Max 30 seconds
Average ramp-down rate (Tp to Tsmax)
6°C/second max.
Time 25°C to peak temperature
8 minutes max.
Figure 12
Classification Profile
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Rev. C, 06/12/2015
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IS31BL3231
PACKAGE INFORMATION
DFN-10
Note: All dimensions in millimeters unless otherwise stated.
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Rev. C, 06/12/2015
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IS31BL3231
RECOMMENDED LAND PATTERN
Note:
1. Land pattern complies to IPC-7351.
2. All dimensions in MM.
3. This document (including dimensions, notes & specs) is a recommendation based on typical circuit board manufacturing parameters. Since
land pattern design depends on many factors unknown (eg. user’s board manufacturing specs), user must determine suitability for use.
Integrated Silicon Solution, Inc. – www.issi.com
Rev. C, 06/12/2015
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IS31BL3231
REVISION HISTORY
Revision
Detail Information
Date
A
Initial release
2012.01.16
B
1. P.7 add efficiency chart
2. P.2 add application figure in 50mA(Torch), 500mA(Flash)
3. P.3 add PWM dimming function
4. P.5 remove ESD
2012.12.03
C
1. Add land pattern
2. Correct 100kHz to 100Hz in Pin Description
3. Add ESD value
2015.06.12
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