TEXAS INSTRUMENTS TPS60231 Technical data
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VIN
C1+
C1−
C2+
C2−
EN1
EN2
GND
PGND
VOUT
D1
D2
D3
ISET
0.47 F
0.47 F
1 F
1 F
VIN = 2.7 V
to 6.5 V
WHITE LED CHARGE PUMP CURRENT SOURCE
WITH PWM BRIGHTNESS CONTROL
FEATURES DESCRIPTION
• Regulated Output Current With 0.4%
Matching
• Drives up to 3 LEDs at 25 mA Each
• LED Brightness Control Through PWM
Control Signal
• High Efficiency by Fractional Conversion
With 1x and 1.5x Modes
• 1 MHz Switching Frequency
• 2.7 V to 6.5 V Operating Input Voltage Range
• Internal Softstart Limits Inrush Current
• Low Input Ripple and Low EMI
• Overcurrent and Overtemperature Protected
• Undervoltage Lockout With Hysteresis
• Ultra-Small 3mm x 3mm QFN Package
APPLICATIONS
• White LED Backlight for Color Displays in
Cellular Phones, Smart Phones, PDAs,
Handheld PCs, Digital Cameras, and
Camcorders
• Keypad Backlight
TPS60231
SLVS544 – OCTOBER 2004
The TPS60231 charge pump is optimized for white
LED supplies in color display backlight applications.
The device provides a constant current for each LED,
which the initial value can be set by an external
resistor. The supply voltage ranges from 2.7 V to
6.5 V and is ideally suited for all applications powered
by a single LI-Ion battery cell or three to four NiCd,
NiMH, or alkaline battery cells. Over an input voltage
range from 3.1 V to 6.5 V, the device provides a high
output current of up to 25 mA per LED with a total of
75 mA. High efficiency is achieved by utilizing a
1x/1.5x fractional conversion technique in combination with very low dropout current sources. In
addition, the current controlled charge pump ensures
low input current ripple and EMI. Only two external
1 µF and two 0.47 µF capacitors are required to build
a complete small and low cost power supply solution.
To reduce board space to a minimum, the device
switches at 1 MHz operating frequency and is available in a small 16-pin QFN (RGT) package.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
Copyright © 2004, Texas Instruments Incorporated
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TPS60231
SLVS544 – OCTOBER 2004
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated
circuits be handled with appropriate precautions. Failure to observe proper handling and installation
procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision
integrated circuits may be more susceptible to damage because very small parametric changes could
cause the device not to meet its published specifications.
ORDERING INFORMATION
PACKAGED DEVICE
TPS60231RGTR QFN BKH
(1) T indicates shipment in tape and reel on a mini reel with 250 units
per reel.
(2) R indicates shipment in tape and reel with 3000 units per reel.
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range (unless otherwise noted)
V
Supply voltage –0.3 V to 7 V
I
Voltage at EN1, EN2, VOUT, ISET –0.3 V to V
Output current at VOUT 150 mA
T
Maximum junction temperature 150 ° C
J
T
Operating free-air temperature –40 ° C to 85 ° C
A
T
Storage temperature –65 ° C to 150 ° C
st
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds 300 ° C
(1) 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 conditions beyond those indicated under "recommended operating
conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(1) (2)
PACKAGE MARKING
(1)
UNIT
I
DISSIPATION RATINGS
PACKAGE
16-Pin QFN (RGT) 1.9 W 20 mW/ ° C 1 W 760 mW
(1) The thermal resistance junction to ambient of the QFN package is 52 ° C/W.
(1)
TA≤ 25 ° C DERATING FACTOR TA= 70 °C TA= 85 °C
POWER RATING ABOVE TA= 25 ° C POWER RATING POWER RATING
RECOMMENDED OPERATING CONDITIONS
MIN TYP MAX UNIT
Supply voltage at VIN 2.7 6.5 V
Maximum output current at VOUT 75 mA
C
Input capacitor 1 µF
i
C
Output capacitor 0.47 1 µF
o
Flying capacitor, C1, C2 0.22 0.47 µF
Operating junction temperature -40 125 °C
2
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TPS60231
SLVS544 – OCTOBER 2004
ELECTRICAL CHARACTERISTICS
VI= 3.6 V, EN1 = EN2 = VI, TA= -40 °C to 85 °C (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
SUPPLY VOLTAGE AND CURRENT
V
I
Q
I
SD
CHARGE PUMP STAGE
V
f Switching frequency 0.75 1 1.25 MHz
η Efficiency VI= 3.7 V, I
CURRENT SINKS
I
Dx
I
Dx
V
Iset Recommended ISET pin current range 4 130 µA
K IDxto ISET current ratio EN2 = EN1 = 1, ISET = 80 µA 230 260 280
V
ENABLE 1, ENABLE 2
V
V
I
IKG
I
IKG
V
Input voltage range IO= 0 mA to 75 mA 2.7 6.5 V
I
Operating quiescent current
VI= 4.2 V, x1-mode, EN1 = EN2 = 1, ISET = 20 µA 200 µA
IO= 0 mA, x1.5-mode 2.1 mA
Shutdown current EN2 = EN1 = GND 0.1 1 µA
Overvoltage limit LED1 unconnected, VI= 4.2 V 5.5 V
OUT
Startup time CO= 1 µF, IDX≥ 0.9 IDX, set 375 µs
Softstart duration 160 µs
= 15 mA each, V
LED
= 3.1 V 83%
DX
Shutdown temperature Temperature rising 160 ° C
Shutdown temperature hysteresis 20 ° C
Input current limit EN2 = EN1 = 1, ISET = 100 µA 350 mA
Recommended maximum current per cur- 3.2 V ≤ VI≤ 6.5 V 25 mA
rent sink
Current into each current sink when ISET 50 mA
is shorted to GND
Current matching between any two outputs V
Line regulation
3.0 V ≤ VI≤ 6.5 V, ISET shorted to GND
= 3.1 V, TA= 25 ° C –2% 0.4% 2%
Dx
3.2 V ≤ VI≤ 6.5 V, V
ISET = 80 µA
= 3.1 V, EN1 = EN2 = 1, ± 3%
Dx
EN2 = 0, EN1 = 1 200
Reference voltage for current set EN2 = 1, EN1 = 0 400 mV
ISET
EN2 = 1, EN1 = 1 580 600 620
EN2 = 0, EN1 = 1 200
Voltage at Dx to GND EN2 = 1, EN1 = 0 300 mV
source
EN2 = 1, EN1 = 1 400
EN1, EN2 high level input voltage 1.3 V
IH
EN1, EN2 low level input voltage 0.3 V
IL
EN1, EN2 trip point hysteresis 50 mV
EN2 input leakage current EN1, EN2 = GND or EN2 = VI, VI= 6.5 V 0.01 1 µA
EN1 input leakage current EN1 = VI, VI= 4.2 V 11 15 µA
Undervoltage lockout threshold Input voltage falling 2.1 V
(UVLO)
Undervoltage lockout hysteresis 50 mV
Frequency range at PWM 0 50 kHz
Recommended ON-time for PWM signal 2.5 µs
Shutdown delay time 0.5 0.85 1.5 ms
Delay time when EN1 = EN2 go to GND after which
the TPS60231 shuts down completely
3
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C2−
C1−
C1+
C2+
PGND
VIN
EN1
D2
D1
VOUT
GND
NC
NC
D3
31 2
7
5
6
8
12 11 10
9
15
13
14
16
EN2
4
QFN PACKAGE
(TOP VIEW)
TPS60231
SLVS544 – OCTOBER 2004
PIN ASSIGNMENT
Terminal Functions
TERMINAL
NAME NO.
C1+ 10 – Connect to the flying capacitor C1
C1– 11 – Connect to the flying capacitor C1
C2+ 9 – Connect to the flying capacitor C2
C2– 12 – Connect to the flying capacitor C2
D1-D3 6-4 I Current sink input. Connect the cathode of the white LEDs to these inputs.
EN1 15 I
EN2 16 I
GND 14 – Analog ground
ISET 1 I Connect a resistor between this pin and GND to set the maximum current through the LEDs.
NC 2, 3 – No internal connection
PGND 7 – Power ground
VIN 13 I Supply voltage input
VOUT 8 0 Connect the output capacitor and the anode of the LEDs to this pin.
Power PAD – – Connect with PGND and GND
I/O DESCRIPTION
Enable input. A logic high enables the converter, logic low forces the device into shutdown mode reducing
the supply current to less than 1 µA if EN2 is tied to GND.
An applied PWM signal reduces the LED current as a function of the duty cycle of the PWM signal. EN1 and
EN2 can be tied together for PWM dimming between 0 mA and the maximum set with ISET. EN1 and EN2
can also be used for digital dimming with 4 steps from 0 mA to the maximum current set with ISET. See the
application section for more details.
4
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D3
D2
D1
C1+
C1−
C2+
C2−
EN2
VOUT
ISET
GND
EN1
Control
R
SET
VIN
Reference
0.47 F
0.47 F
1 F
Charge
Pump
Current
Sinks
1 F
PGND
FUNCTIONAL BLOCK DIAGRAM
TPS60231
SLVS544 – OCTOBER 2004
5
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0
10
20
30
40
50
60
70
80
90
100
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 5.9 6.3
I
LED
= 25 mA
VI − Input Voltage − V
Efficiency − %
I
LED
= 15 mA
I
LED
= 10 mA
I
LED
= 5 mA
0
10
20
30
40
50
60
70
80
90
100
2.7 3.1
3.5 3.9 4.3 4.7 5.1 5.5
5.9 6.3
VI − Input Voltage − V
Efficiency − %
I
LED
= 25 mA
I
LED
= 10 mA
I
LED
= 15 mA
I
LED
= 5 mA
TPS60231
SLVS544 – OCTOBER 2004
TYPICAL CHARACTERISTICS
Table of Graphs
vs Input voltage (I
EN2 = 0, EN1 = 1
η Efficiency
vs Input voltage (I
1, EN1 = 0
vs Input voltage (I
EN2 = EN1 = 1
IQQuiescent current vs Input voltage (T
Maximum output current from charge pump
stage
vs Input voltage (T
fsSwitching frequency vs Free-Air Temperature (T
LED current, I
Line transient response
LED
vs Duty cycle on PWM (I
For f = 32 kHz and f = 1 kHz, DC = 1% to 100%, VI= 3.6 V
VIand ID1vs time on scope, LED current at D1 with 8
VI= 4.2 V to 3.6 V to 4.2 V with EN2 = EN1 = 11, 3 x 20 mA
PWM signal and current at D1 vs time on scope 9, 10
Dimming response f = 32 kHz and f = 1 kHz, VI= 3.6 V, duty cycle = 50%,
EN1 = EN2 = PWM
Startup timing
VI= 3.6 V, 3 x 20 mA, EN1 = EN2 = 00 changed to 11
EN2 = EN1 = 11
= 25 mA, 15 mA, 10 mA, 5 mA per LED),
LED
= 25 mA, 15 mA, 10 mA, 5 mA per LED), EN2 = 2
LED
= 25 mA, 15 mA, 10 mA, 5 mA per LED), 3
LED
= –40 ° C, 25 ° C, 85 ° C) (measured with ID1= 5 mA) 4
A
= –40 ° C, 25 ° C, 85 ° C) 5
A
= -40 ° C to 85 ° C, VI= 3.6 V) 6
A
max set to 20 mA) 7
LED
FIGURE
1
EFFICIENCY EFFICIENCY
vs vs
INPUT VOLTAGE INPUT VOLTAGE
Figure 1. Figure 2.
6
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