ST STP4CMP User Manual
Features
STP4CMP
Low voltage 4-channel constant current
LED driver with charge pump
■ Operating voltage range: V
(opr) = 2.7 V to
CC
5.5 V
■ Full RGB function support
■ 4-channel LED driver with individual ON/OFF
control directly from input pins
■ Individual programmable output current for the
4 channels through 4 external resistors with a
max. capability of 30 mA
■ Absolute output current accuracy of max. ±7%
and channel-to-channel mismatch of max.
±
4%
■ Selectable charge pump enable/disable
■ Thermal protection
■ Small QFN20 (1.8 x 3.2 mm) package
Applications
■ Mobile phone display backlighting
■ RGB LED indicator drivers
Description
QFN20
(1.8 x 3.2 mm)
provide brightness control. When enabled, the
charge pump, which uses a small ceramic bucket
capacitor between C1P and C1N, operates to
regulate the V
with a clamping voltage at typ.
OUT
5 V. The tiny QFN20 (1.8 x 3.2 mm) package
allows the device to be also used for applications
with space limitation.
The STP4CMP is a charge pump based 4channel LED driver designed for RGB illumination
or LCD display backlighting. The STP4CMP
works off a battery with an input voltage between
2.7 V - 5.5 V. The device generates regulated
current sinks with high absolute and channel-tochannel accuracy to drive up to 4 LEDs. It can
support LEDs with forward voltage as high as 3.8
V. The current sink for each channel can be set
with 4 individual external resistors. Each channel
is controlled independently. The PWM control can
be applied directly to the 4 EN (enable) pins to
Table 1. Device summary
Order code Package Packaging
STP4CMPQTR QFN20 Tape and reel
January 2012 Doc ID 15770 Rev 2 1/22
www.st.com
22
Contents STP4CMP
Contents
1 Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5 Detailed description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1 Enable pin (EN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.2 LED turn-on pin (ONx) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.3 Programmable output current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.4 Charge pump . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.5 Thermal protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7 PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1 Recommended . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.2 Demonstration board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.3 Demonstration board schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
9 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2/22 Doc ID 15770 Rev 2
STP4CMP Schematic
1 Schematic
Figure 1. Application schematic
GND
ON1
C
C
V
OUT
VCC
LED1
LED2
LED3
LED4
C2
C3
LED1
LED2
LED3
LED4
C1
C
OUT
AM00798V1
ON2
ON3
ON4
EN
I
SET1
R
SET1
I
SET2
R
SET2
I
SET3
R
SET3
I
SET4
R
SET4
GND
CP_Sel
Figure 1
shows the typical application diagram with the external components. To ensure an
optimal charge pump performance, it is highly recommended that the bucket capacitor, C1,
and the output capacitor, C
, to be placed as close as possible to the pins.
OUT
Table 2. Typical external components
Component Manufacturer Part number Value Size
MURATA GRM155R61A105KE15D
C1- C
OUT
TDK C1005X5R1A105MT
1 µF / 10 V 0402
MURATA GRM188R60J106ME84
C2
10 µF / 6.3 V 0603
TDK C1608X5R0J106MT
MURATA GRM155R60J104KA01D
C3
100 nF 0402
TDK C1005X5R1C104KT
R
LED1-4
1. R
(1)
SET1-4
(2)
: 649 Ω - 7.87 kΩ according to the desired output current from each channel.
SET1-4
2. LED1-4: typ. forward voltage of 3.8 V.
Tyco CPF0402B976RE1 976 Ω 0402
Note: All the above components refer to a typical application. Operation of the device is not limited
to the choice of these external components.
Doc ID 15770 Rev 2 3/22
Schematic STP4CMP
Figure 2. Block schematic
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4/22 Doc ID 15770 Rev 2
!-6
STP4CMP Pin configuration
2 Pin configuration
Figure 3. Pin connection (top through view)
340#-0
Table 3. Pin description
Pin number Symbol Name and function
1 ON1 LED1 enable
2 ON2 LED2 enable
!-6
3 ON3 LED3 enable
4 ON4 LED4 enable
5 EN Chip enable
6I
7I
8I
9I
SET1
SET2
SET3
SET4
LED1 max. current setting resistor
LED2 max. current setting resistor
LED3 max. current setting resistor
LED4 max. current setting resistor
10 GND Ground
11 CP_Sel Charge pump mode selection, ‘1’ => enable; ‘0’ => disable
12 LED4 4
13 LED3 3
th
LED current sink
rd
LED current sink
14 LED2 2nd LED current sink
15 LED1 1
16 V
17 V
18 C
CC
OUT
1P
st
LED current sink
Supply voltage
Charge pump output
Positive terminal of charge pump bucket capacitor
Doc ID 15770 Rev 2 5/22
Pin configuration STP4CMP
Table 3. Pin description (continued)
Pin number Symbol Name and function
19 C
Negative terminal of charge pump bucket capacitor
1N
20 GND Ground
6/22 Doc ID 15770 Rev 2
STP4CMP Maximum ratings
3 Maximum ratings
Table 4. Absolute maximum ratings
Symbol Parameter Value Unit
ON
; VCC;
1-4
EN; CP_Sel;
C1P; C1N;
VOUT Output voltage - 0.3 to +6 V
LED
; ISET
1-4
Supply voltage - 0.3 to +6 V
Current setting - 0.3 V to 2 V
1-4
Machine model ± 200
ESD
VHuman body model (MIL STD_883) ±1500
Charged device model ± 500
T
T
AMB
T
J
STG
Operating ambient temperature - 30 to 85 °C
Maximum operating junction temperature + 150 °C
Storage temperature - 65 to 150 °C
Note: Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these conditions is not implied.
Table 5. Recommended operating conditions
Val ue
Symbol Parameter
V
T
I
LED
T
pwm_ON
T
pwm_OFF
Supply voltage 2.7 - 5.5 V
CC
Operating temperature -40 - 85 °C
op
Current through each LED 2.5 - 30 mA
ON time of PWM signal at each ON
pin
OFF time of PWM signal at each ON
pin
Min. Typ. Max.
33 - µs
33 - µs
Unit
V
LED forward voltage - 3.8 V
fw
Table 6. Thermal data
Symbol Parameter Value Unit
(1)
R
thJA
1. This parameter corresponds to the PCB board, 4-layers with 1inch² of cooling area.
Junction to ambient thermal resistance 70 °C/W
Doc ID 15770 Rev 2 7/22
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