GMT G5121TP1U

G5121
Global Mixed-mode Technology Inc.
Fixed Frequency White LED Step-Up Converter
Features
General Description
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The G5121 is a step-up DC/DC converter specifically
designed to drive up to 5 series white LEDs with constant current. Series connection of the LEDs provides
identical LED currents resulting in uniform brightness
and eliminates the need for ballast resistors. The
G5121 switches at 1MHz, allowing the use of tiny external components. A low 0.254V feedback voltage
minimizes power loss in the current setting resistor for
high efficiency. The OVP pin monitors the output voltage and turns off the converter whenever the LEDs are
open.
Inherently Matched LED Current
High Efficiency: 87%
Drives Up to Five LEDs from 2.5V Supply
24V Internal Power Switch
Fast 1MHz Switching Frequency
Uses Tiny 1mm Tall Inductors
Requires Only 1µF Output Capacitors
19.5V Over Voltage Protection
„ SOT-23-6 and TSOT-23-6 Package
Applications
The G5121 is available in low profile SOT-23-6 and
TSOT-23-6 package.
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White LED Backlight Display for PDA
Pocket PC
Smart Phones
Handheld Devices
„ Cellular Phones
Ordering Information
ORDER
NUMBER
MARKING
TEMP.
RANGE
PACKAGE
(Pb free)
G5121TB1U
G5121TP1U
5121x
5121x
-40°C ~ +85°C
-40°C ~ +85°C
SOT-23-6
TSOT-23-6
Note:TB: SOT23-6 TP: TSOT-23-6
1: Bonding Code
U: Tape & Reel
Pin Configuration
Typical Application Circuit
SW
1
D1
L1
G5121
VIN
2.7V to 4.2V
6
4.7µH
VCC
VCC
SW
C2
1µF/25V
5 LEDs
OVP
GND
5
2
C1
4.7µF/6.3V
OVP
PWM Dimming
Waveform
FB
4
3
G5121
SHDN
GND
FB
RS
SHDN
SOT-23-6/TSOT-23-6
C1:TAIYO YUDEN, JMK212BJ475KD
C2:TAIYO YUDEN, TMK316BJ105KD
TEL: 886-3-5788833
http://www.gmt.com.tw
Ver: 1.3
Nov 13, 2006
1
G5121
Global Mixed-mode Technology Inc.
Absolute Maximum Ratings
Junction Temperature. . . . . . . . . . . . . . . . . . . . . .125°C
Storage Temperature . . . . . . . . . . . . . ..-65°C to 150°C
Reflow Temperature (soldering, 10sec) . . . . . . . 260°C
ESD Rating (Human Body Model) . . . . . . . . . . . . . .2kV
VCC, SHDN to GND. . . . . . . . . . . . . . . . .-0.3V to +7V
FB to GND. . . . . . . . . . . . . . . . . . . . . . . . .-0.3V to VCC
SW, OVP to GND. . . . . . . . . . . . . . . . . . . -0.3V to +24V
Operating Temperature . . . . . . . . . . . . . .-40°C to 85°C
Stress beyond those listed under “Absolute Maximum Rating” may cause permanent damage to the device.
Electrical Characteristics
(VCC=V SHDN =3.6V, TA=25°C)
PARAMETER
CONDITIONS
Input Voltage Range
Input Voltage UVLO
MIN
TYP
MAX
UNITS
2.5
---
6
V
1.7
2.0
2.3
V
Over Voltage Protection Threshold
trigger
18.5
19.5
21
V
Over Voltage Protection Threshold
release
13.5
15
16.5
V
OVP Pin Input Current
Vovp = 16V
---
40
60
µA
VFB = 0.3V (no switching)
---
80
120
µA
VFB = 0.2V (switching)
V SHDN = 0V
---
---
2
mA
---
0.1
1
µA
Quiescent Current
FB Comparator Trip Point
Switching Frequency
Initial Accuracy
244
254
264
mV
Temperature Coefficient
---
100
---
ppm/°C
VFB = 0.2V
0.8
1.0
1.2
MHz
85
---
---
%
Maximum Duty
Switch RDS(ON)
ISW = 150mA
---
0.7
1.0
Ω
Switch Leakage Current
VSW = 20V
---
0.1
10
µA
500
600
700
mA
---
120
---
µs
SHDN Pin Voltage High
2
---
---
V
SHDN Pin Voltage Low
---
---
0.8
V
Switch Current Limit
Soft Start Time
TEL: 886-3-5788833
http://www.gmt.com.tw
Ver: 1.3
Nov 13, 2006
2
G5121
Global Mixed-mode Technology Inc.
Typical Performance Characteristics
(VCC= +3.6V, V SHDN = +3.6V, L=4.7µH, TA=25°C, unless otherwise noted.)
Stability for Driving 5 WLEDs
Stability for Driving 4 WLEDs
Stability for Driving 3 WLEDs
Stability for Driving 2 WLEDs
Inrush Current for Driving 5 WLEDs
Inrush Current for Driving 4 WLEDs
TEL: 886-3-5788833
http://www.gmt.com.tw
Ver: 1.3
Nov 13, 2006
3
G5121
Global Mixed-mode Technology Inc.
Typical Performance Characteristics (continued)
Inrush Current for Driving 2 WLEDs
Inrush Current for Driving 3 WLEDs
Dimming Control for Driving 4 WLEDs
OVP Waveform
Efficiency vs. Load Current
Efficiency vs. Load Current
90
90
80
80
V IN=2.7V
V IN=3.6V
V IN=2.7V
V IN=4.2V
70
Efficiency (%)
Efficiency (%)
70
60
50
40
30
V IN=4.2V
V IN=3.6V
60
50
40
30
5LEDs, CO=1µF
20
4LEDs, CO=1µF
20
10
10
0
5
10
15
Load Current (mA)
20
25
0
5
10
15
Load Current (mA)
20
25
TEL: 886-3-5788833
http://www.gmt.com.tw
Ver: 1.3
Nov 13, 2006
4
G5121
Global Mixed-mode Technology Inc.
Typical Performance Characteristics (continued)
Efficiency vs. Load Current
Efficiency vs. Load Current
90
90
80
V IN=2.7V
V IN=2.7V
60
50
40
30
60
50
40
30
3LEDs, CO=1µF
20
2LEDs, CO=1µF
20
10
10
0
5
10
15
Load Current (mA)
20
25
0
5
IQ_NoSW vs. Input Voltage
130
100
120
90
110
100
80
90
70
80
70
60
50
40
30
20
10
10
0
3
3.5
4
4.5
Input Voltage (V)
5
25
50
30
20
2.5
20
60
40
2
10
15
Load Current (mA)
IQ_NoSW vs. Temperature
IQ_NoSW (µA)
IQ_NoSW (µA)
V IN=3.6V V IN=4.2V
70
Efficiency (%)
Efficiency (%)
70
80
V IN=3.6V V IN=4.2V
5.5
0
-40
6
-20
Frequency vs. Input Voltage
0
20
40
60
Temperature ( °C)
80
100
Frequency vs. Temperature
1
1.1
1.05
0.95
Frequency (MHz)
Frequency (MHz)
1
0.9
0.85
0.8
0.95
0.9
0.85
0.8
0.75
0.75
0.7
-40
0.7
2
2.5
3
3.5
4
4.5
Input Voltage (V)
5
5.5
6
-20
0
20
40
60
Temperature ( °C)
80
100
TEL: 886-3-5788833
http://www.gmt.com.tw
Ver: 1.3
Nov 13, 2006
5
G5121
Global Mixed-mode Technology Inc.
Typical Performance Characteristics (continued)
OVP Trigger Threshold vs. Temperature
21
21
20.5
20.5
OVP Trigger Threshold (V)
OVP Trigger Threshold (V)
OVP Trigger Threshold vs. Input Voltage
20
19.5
19
18.5
18
17.5
20
19.5
19
18.5
18
17.5
17
2
2.5
3
3.5
4
4.5
Input Voltage (V)
5
5.5
17
-40
6
17
16.5
16.5
16
15.5
15
14.5
14
13.5
20
40
60
Temperature ( °C)
80
100
16
15.5
15
14.5
14
13.5
13
2
2.5
3
3.5
4
4.5
Input Voltage (V)
5
5.5
13
-40
6
OVP Pin Input Current vs. Input Voltage
-20
0
20
40
60
Temperature ( °C)
80
100
OVP Pin Input Current vs. Temperature
60
60
50
50
OVP Pin Input Current (µA)
OVP Pin Input Current (µA)
0
OVP Release Threshold vs. Temperature
17
OVP Release Threshold (V)
OVP Release Threshold (V)
OVP Release Threshold vs. Input Voltage
-20
40
30
20
10
40
30
20
10
0
2
2.5
3
3.5
4
4.5
Input Voltage (V)
5
5.5
0
-40
6
-20
0
20
40
60
Temperature ( °C)
80
100
TEL: 886-3-5788833
http://www.gmt.com.tw
Ver: 1.3
Nov 13, 2006
6
G5121
Global Mixed-mode Technology Inc.
Recommended Minimum Footprint
SOT-23-6/TSOT-23-6
Block Diagram
FB
SW
OVP
COMPENSATION
COMPARATOR
A1
+
A2
+
DRIVER
Q
R
CONTROL
M1
S
0.254V
VREF
+
RAMP
GENERATOR
OC
1MHz
OSCILLATOR
VCC
SHDN
GND
TEL: 886-3-5788833
http://www.gmt.com.tw
Ver: 1.3
Nov 13, 2006
7
Global Mixed-mode Technology Inc.
G5121
Pin Description
PIN
NAME
1
2
SW
GND
FUNCTION
3
FB
4
SHDN
Ground Pin.
Feedback Pin. Connect current setting resistor Rs from this pin to ground. The LED current is set as
0.254V/ Rs.
Active Low Shutdown Pin.
5
6
OVP
VCC
Over Voltage Protection Sense Pin.
Input Supply Pin. Bypass this pin with a capacitor as close to the device as possible.
Switch Pin. The drain of the internal NMOS power switch. Connect this pin to inductor.
Function Description
Since the G5121 is designed to operate in discontinuous mode, the inductor current reaches zero during
discharge phase. After the inductor current reaches
zero, the switch pin exhibits ringing due to the LC tank
circuit formed by the inductor in combination with
switch and diode capacitance. This ringing is not
harmful; far less spectral energy is contained in the
ringing than in the switch transitions. The ringing can
be damped by application of a 300Ω resistor across
the inductor, although this will degrade efficiency.
Normal Operation
The G5121 uses a constant frequency control scheme
to provide excellent line and load regulation. Operation
can be best understood by referring to the block diagram. At the start of each oscillator cycle, the SR latch
is set, which turns on the power switch M1. An artificial
ramp is generated to the positive terminal of the PWM
comparator A2. When this voltage exceeds the level at
the negative input of A2, the SR latch is reset turning
off the power switch. The level at the negative input of
A2 is set by the error amplifier A1, and is simply an
amplified version of the difference between the feedback voltage and the reference voltage of 0.254V. In
this manner, the error amplifier sets the correct peak
current level to keep the output in regulation. If the
error amplifier’s output increases, more current is delivered to the output, if it decreases, less current is
delivered.
Capacitor Selection
The small size of ceramic capacitors makes them suitable for G5121 applications. X5R and X7R types are
recommended because they retain their capacitance
over wider voltage and temperature ranges than other
types such as Y5V or Z5U. A minimum 1µF capacitor
for output is required for most applications. Larger input/output capacitor minimizes input/output ripple.
Diode Selection
Schottky diodes, with their low forward voltage drop
and fast reverse recovery, are the ideal choices for
G5121 applications. The forward voltage drop of a
Schottky diode represents the conduction losses in the
diode, while the diode capacitance (CT or CD) represents the switching losses. For diode selection, both
forward voltage drop and diode capacitance need to
be considered. Schottky diodes with higher current
ratings usually have lower forward voltage drop and
larger diode capacitance, which can cause significant
switching losses at the 1MHz switching frequency of
the G5121. A Schottky diode rated at 500mA is sufficient for most G5121 applications.
Over Voltage Protection
Over voltage protection function is designed to prevent
the damage of internal NMOS switch in case the increased impedance of the LED load (include the LED
opened). Once the device detects over voltage (typical
19.5V) at the output, the internal NMOS switch is kept
off until the output voltage drops below 15V.
Application Information
Inductor Selection
A 4.7µF inductor is recommended for G5121 applications. Small size and high efficiency are the major
concerns for most G5121 applications. Inductor with
low core losses and small DCR (cooper wire resistance) at 1MHz are good choice for G5121 applications.
TEL: 886-3-5788833
http://www.gmt.com.tw
Ver: 1.3
Nov 13, 2006
8
G5121
Global Mixed-mode Technology Inc.
Package Information
C
D
L
E
H
θ1
e1
e
A
A2
A1
b
SOT-23-6 (TB) Package
Note:
1. Package body sizes exclude mold flash protrusions or gate burrs
2. Tolerance ±0.1000 mm (4mil) unless otherwise specified
3. Coplanarity: 0.1000mm
4. Dimension L is measured in gage plane
MIN.
DIMENSION IN MM
NOM.
MAX.
MIN.
DIMENSION IN INCH
NOM.
MAX.
A
A1
A2
b
C
1.00
0.00
0.70
0.35
0.10
1.10
----0.80
0.40
0.15
1.30
0.10
0.90
0.50
0.25
0.039
0.000
0.028
0.014
0.004
0.043
----0.031
0.016
0.006
0.051
0.004
0.035
0.020
0.010
D
E
e
2.70
1.40
-----
2.90
1.60
1.90(TYP)
3.10
1.80
-----
0.106
0.055
-----
0.114
0.063
0.075(TYP)
0.122
0.071
-----
H
L
θ1
2.60
0.37
2.80
------
3.00
-----
0.102
0.015
0.110
-----
0.118
-----
1º
5º
9º
1º
5º
9º
SYMBOL
TEL: 886-3-5788833
http://www.gmt.com.tw
Ver: 1.3
Nov 13, 2006
9
G5121
Global Mixed-mode Technology Inc.
C
D
L
E1 E
θ1
e
e1
A2
y
A
b
A1
TSOT-23-6 (TP) Package
Note:
1. Dimension D does not include mold flash, protrusions or tate burrs. Mold flash, protrusions or gate burrs shall not exceed
0.1mm PER end. Dimension E1 does not include interlead flash or protrusion. Interlead flash or protrusion shall not exceed 0.15mm PER side.
2. The package top may be smaller than the package bottom. Dimensions D and E1 are determined at the outermost extremes of the plastic body exclusive of mold flash, tie bar burrs, gate burrs and interlead flash, but including any mismatch between the top and bottom of the plastic body.
SYMBOL
A
A1
A2
b
C
D
E
E1
e
e1
L
y
θ1
MIN.
DIMENSION IN MM
NOM.
0.75
0.00
0.70
0.35
0.10
2.80
2.60
1.50
0.37
----0°
--------0.75
--------2.90
2.80
1.60
0.95 BSC
1.90 BSC
-------------
MAX.
MIN.
1.00
0.10
0.80
0.51
0.25
3.00
3.00
1.70
0.030
0.000
0.028
0.014
0.004
0.110
0.102
0.059
----0.10
8°
0.015
DIMENSION IN INCH
NOM.
0°
--------0.030
--------0.114
0.110
0.063
0.0374 BSC
0.0748 BSC
-------------
MAX.
0.039
0.004
0.031
0.020
0.010
0.118
0.118
0.067
----0.004
8°
Taping Specification
PACKAGE
Q’TY/REEL
SOT-23-6
TSOT-23-6
3,000 ea
3,000 ea
Feed Direction
SOT- 23-6 / TSOT-23-6 Package Orientation
GMT Inc. does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and GMT Inc. reserves the right at any time without notice to change said circuitry and specifications.
TEL: 886-3-5788833
http://www.gmt.com.tw
Ver: 1.3
Nov 13, 2006
10