ETC STOD14

STOD14
700 mA dual DC-DC converter for powering AMOLED displays
Datasheet — production data
Features
■
Step-down and inverter converters
■
Operating input voltage range from 6 V to 13 V
■
Synchronous rectification for both converters
■
700 mA output current
■
Fixed positive voltage 4.6 V
■
Programmable negative voltage by SWIRE from
- 2.4 V to - 6.0 V
■
Typical efficiency 85%
■
PWM mode controller @ 1.6 MHz switching
frequency
■
Enable pin for shutdown mode
■
Low quiescent current in shutdown mode
■
Soft-start with inrush current protection
■
Short-circuit protection on positive output
■
Overtemperature protection
■
Temperature range - 40 °C to 85 °C
■
True shutdown mode
■
Fast output discharge after shutdown
■
Package DFN 4x4 mm 12 leads 0.75 mm
height, 0.5 mm pitch
Applications
■
Digital photo frames
■
Ultra mobile PCs
■
Mobile Internet devices
■
Digital still cameras / camcorders
■
Portable media players / DVD players
Table 1.
DFN12L (4 x 4 mm)
Description
The STOD14 is a dual channel DC-DC converter
driver for medium-sized AMOLED display panels.
It integrates a step-down and an inverting
converter in a compact IC design. The excellent
efficiency makes it particularly suitable for battery
operated products. The high frequency operation
allows the value and size of external components
to be reduced.
The positive output voltage is fixed at 4.6 V with
very high current capability and is generated
using a buck converter. The negative output is
programmable by an external MCU through a
dedicated pin which implements single-wire
protocol, with values from - 2.4 to - 6.0 V.
Soft-start with controlled inrush current limit, load
disconnect and thermal shutdown are integrated
functions of the device.
Device summary
Order code
Positive voltage
Negative voltage
Package
Packaging
STOD14PUR
4.6 V
- 2.4 V to - 6.0 V
DFN12L (4 x 4 mm)
3000 parts per reel
August 2012
This is information on a product in full production.
Doc ID 023562 Rev 1
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www.st.com
22
Contents
STOD14
Contents
1
Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2
Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3
Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4
Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5
Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6
Application Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7
6.1
Inductor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.2
Input and output capacitor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.3
Recommended PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Detailed description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.1
Mode of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.2
Enable pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.3
Soft-start and inrush current limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.4
Startup sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.5
Fast discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.6
Undervoltage lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.7
Overtemperature protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.8
Short-circuit startup detection (SSD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.9
Overload protection (OLP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.10
Short-circuit protection (SCP) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.11
S-WIRE protocol description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.12
Enable and S-WIRE operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.13
Programming negative output voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8
Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
9
Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
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STOD14
1
Schematic
Schematic
Figure 1.
Table 2.
Application schematic
Typical external components
Description
Manufacturer
Part number
Value
Size
Ratings
L1
Coilcraft
LPS4012-472MLB
4.7 µH
4 x 4 x 1.2
1.6 A / 1.8 A (1)
L2
Coilcraft
LPS4012-472MLB
4.7 µH
4 x 4 x 1.2
1.6 A / 1.8 A (1)
CINA
Murata
GRM21BR61C106KE15L
10 µF
0805
X5R, 16 V
CINP
Murata
2x GRM21BR61C106KE15L
2x 10 µF (2)
0805
X5R, 16 V
CO1
Murata
2x GRM21BR61C106KE15L
2x 10 µF
0805
X5R, 16 V
CO2
Murata
2x GRM21BR61C106KE15L
2x 10 µF
0805
X5R, 16 V
CREF
Murata
GRM185R60J105KE26D
1.0 µF
0603
X5R, 6.3 V
1. ISAT 10% drop / 30% drop.
2. Doubled CINP useful at low temperatures.
Note:
All the above components refer to the typical application performance characteristics.
Operation of the device is not limited to the choice of these external components.
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Schematic
STOD14
Block schematic
VINA
VINP_BK
P1
LX1
MOSFET
CONTROL
EA
DMD
RES
DIVIDER
VINP_IV
RING
KILLER
Figure 2.
VREF
N1
VREF
SOFT
START
RES
DIVIDER
EN
MOSFET
CONTROL
EA
FAST
DISCHARGE
P2
VO2
ENABLE
UVLO
OTP
AGND
4/22
VO1
SWIRE
N2
RING
KILLER
S-WIRE
FAST
DISCHARGE
OSC
PGND
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DMD
LX2
STOD14
2
Pin configuration
Pin configuration
Figure 3.
Pin configuration (top view)
PGND
Table 3.
Pin description
Symbol
Pin
VO2
1
Inverting converter output voltage (negative)
LX2
2
Switching node of the inverting converter
VinIV
3
Power input supply voltage for inverting converter
VinBK
4
Power input supply voltage for step-down converter
LX1
5
Switching node of the step-down converter
PGND
6
Power ground pin
VO1
7
Step-down converter output voltage (positive)
AGND
8
Signal ground pin. This pin must be connected to power ground pin
SWIRE
9
S-WIRE pin
VinA
10
Analog input supply voltage
EN
11
Enable control pin. ON = HIGH. When pulled low, puts the device
into shutdown mode
VREF
12
Voltage reference output. Connect 1 µF bypass capacitor between
this pin and AGND
EXPOSED PAD
Description
Exposed pad must be connected to AGND and PGND in the PCB
layout in order to guarantee proper operation of the device.
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Maximum ratings
3
STOD14
Maximum ratings
Table 4.
Absolute maximum ratings
Symbol
Parameter
Value
Unit
VinA, VinIV,
DC supply voltage
VinBK
- 0.3 to 13.5
V
EN, SWIRE Enable pin, S-WIRE pin
- 0.3 to 4.6
V
Internally limited
A
ILx2
Inverting converter switching current
Lx2
Inverting converter switching node
- 6.5 to VINP +0.3
V
VO2
Inverting converter output voltage
- 6.0 to GND +0.3
V
VO1
Step-down converter output voltage
- 0.3 to 6
V
Lx1
Step-down converter switching node
- 0.3 to VINP +0.3
V
ILx1
Step-down converter switching current
Internally limited
A
VREF
Reference voltage
- 0.3 to 3
V
PD
Power dissipation
Internally limited
mW
- 65 to 150
°C
150
°C
2
kV
TSTG
TJ
ESD
Storage temperature range
Maximum junction temperature
Human body model ESD protection
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.
Thermal data
Symbol
Parameter
RthJA
Thermal resistance junction-ambient (1)
RthJC
Thermal resistance junction-case (FR-4 PCB)
1. The package is mounted on a 4-layer (2S2P) JEDEC board as per JESD51-7 and JESD51-5.
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Value
Unit
33
°C/W
1.64
°C/W
STOD14
4
Electrical characteristics
Electrical characteristics
TA = 25 °C, VINA = VINP = 9.0 V, IO1,2 = 150 mA, CIN = 10 µF, CO1,2 = 22 µF, CREF = 1 µF,
L1 = 4.7 µH, L2 = 4.7 µH, VEN = High, VO1 = 4.6 V, VO2 = - 4.9 V, unless otherwise specified.
Table 6.
Electrical characteristics
Symbol
Parameter
VIN
Operating input voltage
range
TA = - 40 to 85 °C
UVLO_H
Undervoltage lockout
HIGH
VINA rising, TA = -40 to 85 °C
UVLO_L
Undervoltage lockout
LOW
VINA falling, TA = -40 to 85 °C
Input current
No load condition (I_VI = IINA + IINP)
IQ_SH
Shutdown current
VEN = GND, (IQ_SH = IINA + IINP)
VEN H
Enable HIGH threshold
VINA = 6 V to 13 V, TA = -40 to 85 °C
VEN L
Enable LOW threshold
VINA = 6 V to 13 V, TA = -40 to 85 °C
IEN
Enable input current
VEN = VIN
FSW
Frequency
PWM mode, TA = -40 to 85 °C
D1MAX
Step-down maximum
duty cycle
No load
90
%
D2MAX
Inverting maximum duty
No load
cycle
90
%
IO1,2 = 10 to 150 mA
VO1=4.6 V, VO2=-4.9 V
see figure
%
IO1,2 =150 to 700 mA
VO1=4.6 V, VO2=-4.9 V
85
%
I_VI
η
Test conditions
Total system efficiency
Min.
Typ.
6
5
4.6
Max.
Unit
13
V
5.2
V
4.8
V
30
mA
5
1.2
1.44
VREF
Voltage reference
IREF = 10 μA
IREF
Voltage reference
current capability
At VREF = VREF – 1.5%
100
VINA=6 V to 13 V, IO1=5 mA to 700
mA, TA=-40 °C to 85 °C
4.55
1.198
µA
V
1.6
1.211
0.4
V
1
µA
1.76
MHz
1.222
V
µA
Step-down converter section
VO1
ΔVO1 SL
ΔVO1
IO1
Output voltage
Static line regulation
(1)
Static load regulation
Maximum step-down
output current
(2)
4.6
VINA=6 V to 13 V, IO1=5 mA IO2 no
load; TA=-40 °C to 85 °C
0.5
VINA=6 V to 13 V, IO1=700 mA IO2 no
load, TA=-40 °C to 85 °C
0.5
IO1=5 to 700 mA, IO2 no load, VINA=6
V; TA=-40 °C to 85 °C
1
IO1=5 to 700 mA, IO2 no load,
VINA=13 V; TA=-40 °C to 85 °C
1
VI=6 V to 13 V
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4.65
V
%
%
700
mA
7/22
Electrical characteristics
Table 6.
Electrical characteristics (continued)
Symbol
I-L1MAX
STOD14
Parameter
Test conditions
Inductor peak current
VO1 below 10% of nominal value
Min.
Typ.
Max.
1.2
Unit
A
RDSONP1
TA = -40 to 85 °C
0.2
0.5
Ω
RDSONN1
TA = -40 to 85 °C
0.18
0.5
Ω
-2.4
V
Inverting converter section
Output negative voltage 41 discrete values with 100 mV steps
range
set by SWIRE pin
VO2
ΔVO2 SL
ΔVO2
IO2
I-L2MAX
Default value
Default output voltage
Accuracy
Output voltage variation on the
nominal value
Static line regulation (3)
Static load regulation
(4)
-6.0
-4.9
-1.4
+1.4
VINA=6 V to 13 V, IO2=5 mA IO1 no
load; TA=-40 °C to 85 °C
1
VINA=6 V to 13 V, IO2=700 mA IO1 no
load, TA=-40 °C to 85 °C
1
IO2=5 to 700 mA, IO1 no load, VINA=6
V; TA=-40 °C to 85 °C
1
IO2=5 to 700 mA, IO1 no load,
VINA=13 V; TA=-40 °C to 85 °C
1
Maximum inverting
output current
VINA=6 V to 13 V
Inductor peak current
VO2 below 10% of nominal value
V
%
%
%
-700
mA
-2.0
A
RDSONP2
TA = -40 to 85 °C
0.17
0.5
Ω
RDSONN2
TA = -40 to 85 °C
0.16
0.5
Ω
Thermal shutdown
OTP
OTPHYST
Overtemperature
protection
150
°C
Overtemperature
protection hysteresis
15
°C
300
Ω
15
ms
Discharge resistor
RDIS
Discharge resistor value
TDIS
Discharge time
No load, from 90% to 10%
1. [(VO1MAX - VO1MIN) / (VO1 @ 25 °C and VINA,P = 6 V)] x 100.
2. [(VO1MAX - VO1MIN) / (VO1 @ 25 °C and IO1 = 5 mA)] x 100.
3. [(VO2MAX - VO2MIN) / (VO2 @ 25 °C and VINA,P = 6 V)] x 100.
4. [(VO2MAX - VO2MIN) / (VO2 @ 25 °C and IO2 = 5 mA)] x 100.
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STOD14
5
Typical performance characteristics
Typical performance characteristics
Efficiency[%]
Figure 4.
Total system efficiency @ 25 °C, (L1 = L2 = LPS4012-472MLB)
90.0
87.5
85.0
82.5
80.0
77.5
75.0
72.5
70.0
67.5
65.0
6V
7V
9V
12 V
13 V
0
50
100
150
200
250
300
350
400
450
500
550
600
650
700
I LOAD [mA]
Figure 5.
Startup and inrush current
Figure 6.
Fast discharge
VINA = VINP = 6 V, No load, TA = 25 °C
VINA = VINP = 6 V, No load, TA = 25 °C
Figure 7.
Figure 8.
Line transient (tR = 10 µs)
VIN = 8.5 V to 9.5 V, Diff. load 100 mA, tR = 10 µs
Line transient (tF = 10 µs)
VIN = 9.5 V to 8.5 V, Diff. load 100 mA, tF = 10 µs
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Typical performance characteristics
Figure 9.
Load transient (tR = 10 µs)
VIN = 6 V, Diff. load 20 to 120 mA, tR = 100 µs
STOD14
Figure 10. Load transient (tF = 10 µs)
VIN = 6 V, Diff. load 120 to 20 mA, tF = 100 µs
Figure 11. PSRR (VIN = 9 V + 1 VPP sinewave, single-ended 100 mA load)
60.0
PSRR [dB]
50.0
40.0
30.0
VO1
VO2
20.0
1,000
10,000
100,000
f [Hz]
Table 7.
10/22
PSRR
f [Hz]
PSRR_VO1 [dB]
PSRR_VO2 [dB]
10
> 60
> 60
100
> 60
> 60
1 000
54
54
2 000
46
48
5 000
40
44
10 000
34
39
20 000
29
35
50 000
31
34
100 000
35
32
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STOD14
Application Information
6
Application Information
6.1
Inductor selection
The inductor is the key passive component for switching converters.
For the step-down converter an inductance between 3.3 µH and 6.8 µH is recommended.
For the inverting stage the suggested inductance ranges from 3.3 µH to 4.7 µH.
It is very important to select a proper inductor according to the maximum current the
inductor can handle in order to avoid saturation. The peak current for the step-down and the
inverting can be calculated with the following formulas:
Equation 1
IPEAK _ BUCK =
VO1 ⋅ (1 − VO1 / VIN )
+ IO
2 ⋅ fs ⋅ L1
Equation 2
IPEAK _ INV =
VIN ⋅ VO2
I (V − VO 2 )
+ O IN
2 ⋅ fs ⋅ L 2 (VO 2 − VIN )
η2 ⋅ VIN
where
VO1 is step-down output voltage
VO2 is inverting output voltage including sign
IO is output current for both DC-DC converters
VIN is input voltage; use minimum of operating voltage
fs is switching frequency; use the minimum value of 1.44 MHz for worst case
η2 is inverter efficiency; typ. 85%
L1 is buck inductor value; including tolerance
L2 is inverter inductor value; including tolerance.
6.2
Input and output capacitor selection
It is recommended to use ceramic capacitors with low ESR as input and output capacitors in
order to filter any disturbance present in the input line and to get stable operation for the
switching converters.
6.3
Recommended PCB layout
The STOD14 is a high frequency power switching device so it requires a proper PCB layout
in order to obtain the necessary stability and optimize line/load regulation and output voltage
ripple. Analog input (VINA) and power input (VINP) must be kept separated and connected
together at the CIN pad only. The input capacitor must be as close as possible to the IC. To
minimize the ground noise, a common ground node for power ground and a different one for
analog ground must be used. The exposed pad is connected to AGND through vias.
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Application Information
STOD14
Figure 12. Top layer and top silkscreen (top view)
Figure 13. Bottom layer and top silkscreen (top view)
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STOD14
7
Detailed description
Detailed description
The STOD14 is a high efficiency dual DC-DC converter which integrates a step-down and
inverting power stage suitable for supplying AMOLED panels.
Thanks to the high level of integration it needs only 6 external components to operate and it
achieves very high efficiency using a synchronous rectification technique for both the DCDC converters.
The controller uses an average current mode technique in order to obtain good stability and
precise voltage regulation in all possible conditions of input voltage, output voltage and
output current. In addition, the peak inductor current is monitored in order to avoid inductor
saturation.
The STOD14 avoids battery leakage thanks to the true-shutdown feature and it is self
protected from overtemperature. Undervoltage lockout and soft-start guarantee proper
operation during startup.
7.1
Mode of operation
To guarantee the minimal output voltage ripple, the device works just in continuous
conduction mode (CCM). In this mode, reverse current pulses flowing back to the power
supply can appear, especially at low load.
7.2
Enable pin
The device operates when the Enable pin is set high. If the Enable pin is set low, the device
stops switching, and all the internal blocks are turned off. In addition, the internal switches
are in an OFF state so the load is electrically disconnected from the input. This avoids
unwanted current leakage from the input to the load.
When the EN is pulled high, the P1 switch is turned on for 100 µs. In normal operation,
during this time, apart of a small drop due to parasitic resistance, VO1 reaches VIN. After 100
µs, if VO1 stays below VIN, the P1 is turned off and stays off until a new pulse is applied to
EN. This mechanism avoids the device starting if a short-circuit is present on VO1.
7.3
Soft-start and inrush current limiting
As a first step, the CO1 capacitor is charged, the P1 switch implements a current limiting
technique in order to keep the charge current below 400 mA. This avoids battery
overloading during startup.
After VO1 reaches VINP voltage level, the P1 switch is fully turned on and the soft-start
procedure for the step-down is started.
After around 2 ms the soft-start for the inverting is started. The positive and negative voltage
is under regulation around 6 ms after the Enable pin is asserted high.
7.4
Startup sequence
After the Enable pin is pulled high, or after a suitable voltage is applied to VINP, VINA and the
Enable pin, the device begins the startup phase. The positive and negative voltages are
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Detailed description
STOD14
under regulation about 10 ms after the Enable pin is asserted high. The short-circuit
protection is designed to prevent overload, performing a dynamic current limitation on both
output pins. At light load condition (up to 150 mA), the load can be connected during the
startup phase. At medium/high load condition (above 150 mA), the proper sequence needs
the startup phase to be entirely completed before connecting a load.
7.5
Fast discharge
When the device goes into shutdown mode and LX1 and LX2 stop switching, the discharge
switch between VO1 and VIN and the switch between VO2 and GND turn on and discharge
the positive and the negative output voltages. After output voltages are discharged to zero,
the switches turn off and the outputs stay in high impedance state.
7.6
Undervoltage lockout
The undervoltage lockout function avoids improper operation of the device when the input
voltage is not high enough. When the input voltage is below the UVLO threshold, the device
is in shutdown mode. The hysteresis avoids unstable operation at input voltage levels close
to the UVLO threshold.
7.7
Overtemperature protection
An internal temperature sensor continuously monitors the IC junction temperature. If the
temperature exceeds the specified value (see Table 5) the device stops operating. As soon
as the temperature falls below the threshold (including hysteresis), normal operation is
restored.
7.8
Short-circuit startup detection (SSD)
During device soft-start on positive output, an internal comparator checks load condition to
detect eventual panel damage. In such case soft-start is stopped and the device is parked in
power-off. To reset the normal functionality (assuming that the anomalous load condition
was removed), it is necessary to restart the converter by an enable transient.
If no damage is detected during soft-start on the positive output, the startup procedure
follows with negative output soft-start to reach, at the end, normal outputs functionality and
voltages.
7.9
Overload protection (OLP)
Output current is internally limited. An overload condition, as a short-circuit between the two
outputs or between each output and GND, produces the device power-off. To reset normal
functionality (assuming that the short condition was removed), it is necessary to restart the
converter by an enable transient.
7.10
Short-circuit protection (SCP)
When short-circuit occurs, the device is able to detect the voltage difference between VIN
and VOUT. Overshoots are limited, decreasing the inductor current. After that, the output
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STOD14
Detailed description
stages of the device are turned off. This status is maintained avoiding current flowing to the
load. A new enable transition is needed to restart the device. The short-circuit protection is
active during startup.
7.11
S-WIRE protocol description
Protocol to digitally communicate over a single cable with single-wire components.
Features and benefits
●
Fully digital signal
●
No handshake needed
●
Protection against glitches and spikes though an internal low-pass filter acting on both
rising and falling edges
●
Uses a single-wire (plus analog ground) to accomplish both communication and power
control transmission
●
Simple design with an interface protocol that supplies control and signaling over a
single-wire connection to set the output voltages.
S-WIRE protocol
●
Single-wire protocol uses conventional CMOS/TTL logic levels (maximum 0.6 V for
logic “zero” and a minimum 1.2 V for the logic “one”) with operation specified over a
supply voltage range of 2.5 V to 4.5 V
●
Both master (MCU) and slave (this device) are configured to permit bit sequential data
to flow only in one direction at a time; master initiates and controls the device
●
Data is bit-sequential with a START bit and a STOP bit
●
Signal is transferred in real time
●
System clock is not required; each single-wire pulse is self-clocked by the oscillator
integrated in the master and asserted valid within a frequency range of 250 kHz
(maximum).
S-WIRE basic operations
The negative output voltage levels are selectable within a wide range (steps of 100 mV). The
device can be enabled / disabled via S-WIRE in combination with the Enable pin.
7.12
Enable and S-WIRE operation
Both S-WIRE and Enable pins can be used to switch on and off the device. Table 8 describes
functionality for all combinations.
Table 8.
EN and S-WIRE operation table
EN
SWIRE
Action
Low
Low
Device off
Low
High
Negative output voltage set by S-WIRE
High
Low
Default negative output voltage
High
High
Default negative output voltage
Doc ID 023562 Rev 1
15/22
Detailed description
STOD14
Note:
Enable pin must be set to AGND while using the S-WIRE function.
7.13
Programming negative output voltage
Negative output voltage is set through the S-WIRE interface by providing a number of pulses
according to the following table.
Table 9.
Negative output voltage programming levels
Bit clock
VO2 (V)
Bit clock
VO2 (V)
Bit clock
VO2 (V)
Bit clock
VO2 (V)
Bit clock
VO2 (V)
1
N/A
11
-5.4
21
-4.4
31
-3.4
41
-2.4
2
N/A
12
-5.3
22
-4.3
32
-3.3
3
N/A
13
-5.2
23
-4.2
33
-3.2
4
N/A
14
-5.1
24
-4.1
34
-3.1
5
-6.0
15
-5.0
25
-4.0
35
-3.0
6
-5.9
16
-4.9
26
-3.9
36
-2.9
7
-5.8
17
-4.8
27
-3.8
37
-2.8
8
-5.7
18
-4.7
28
-3.7
38
-2.7
9
-5.6
19
-4.6
29
-3.6
39
-2.6
10
-5.5
20
-4.5
30
-3.5
40
-2.5
16/22
Doc ID 023562 Rev 1
STOD14
8
Package mechanical data
Package mechanical data
In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK® packages, depending on their level of environmental compliance. ECOPACK
specifications, grade definitions and product status are available at: www.st.com. ECOPACK
is an ST trademark.
Table 10.
DFN12L (4 x 4) mechanical data
mm
Dim.
Min.
Typ.
Max.
A
0.70
0.75
0.80
A1
0
0.02
0.05
b
0.18
0.25
0.30
D
D2
4.0
3.15
E
E2
3.40
4.0
2.50
e
L
3.30
2.65
2.75
0.5
0.30
Doc ID 023562 Rev 1
0.40
0.50
17/22
Package mechanical data
STOD14
Figure 14. DFN12L (3 x 3) drawing
12x b
12x K
D2
A
A1
12x L
E2
e
E
D
8341805_A
18/22
Doc ID 023562 Rev 1
STOD14
Package mechanical data
Tape & reel QFNxx/DFNxx (4x4) mechanical data
mm.
inch.
Dim.
Min.
Typ.
A
Max.
Min.
Typ.
330
C
12.8
D
20.2
N
99
13.2
Max.
12.992
0.504
0.519
0.795
101
T
3.898
3.976
14.4
0.567
Ao
4.35
0.171
Bo
4.35
0.171
Ko
1.1
0.043
Po
4
0.157
P
8
0.315
Doc ID 023562 Rev 1
19/22
Package mechanical data
STOD14
Figure 15. DFN12L footprint recommended data (dimensions in millimeters)
20/22
Doc ID 023562 Rev 1
STOD14
9
Revision history
Revision history
Table 11.
Document revision history
Date
Revision
16-Aug-2012
1
Changes
Initial release.
Doc ID 023562 Rev 1
21/22
STOD14
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22/22
Doc ID 023562 Rev 1
DC-DC converters
for AMOLED power supplies
Introduction
Compact, energy-efficient AMOLED power chips increase battery life of
mobile applications
2
ST’s DC-DC converters for AMOLED power supplies are based on an innovative silicon on insulator (SoI)
process technology that ensures outstanding energy efficiency and results in longer battery life. These
dedicated AMOLED power ICs simplify power-supply circuitry by integrating on the same chip the stepup or step-down and inverting DC-DC converters needed to generate the positive and negative supplies
required by AMOLED displays. They feature a typical efficiency of 85% and an output current capability
ranging from 200 to 700 mA to satisfy the growing size of AMOLED panels. The ICs also feature low output
ripple and high immunity to cell-phone noise, resulting in consistent, flicker-free displays. Integrated
short-circuit and overload protection modes maximize ruggedness and reliability. Energy-saving features
include an enable pin which can be used to completely shut down the device when the display is not
used and pulse-skipping operation to optimize efficiency during low load conditions.
FEATURES
• Digital I/O programming
• Advanced silicon-on-insulator
• Soft start (SS)
• Meets needs for growing AMOLED
panel sizes
• Fast discharge (FD)
• Improved picture quality
• Synchronous rectification
• Over-temperature protection
• Increased ruggedness and reliability
• PFM/PWM operation for best-in-class
• Short-circuit start-up detection (SSD)
TARGET APPLICATIONS
• Overload protection (OLP)
• Tablet PCs
• Short-circuit protection (SCP)
• Smartphones and other slim-line
manufacturing technology
efficiency (up to 90%)
• High frequency (1.6 MHz) for smallest
application area
• High output voltage accuracy
• Overcurrent detection (OCD)
• Low output ripple
BENEFITS
• High immunity to GSM noise
• Increased battery lifetime
• User-programmable negative output
• Simplified power-supply circuitry
voltage
• Flicker-free display
electronics such as digital cameras
• Handheld console and appliance
user interfaces
Positioning Diagram - AMOLED Power Supply
Output current
STOD14
700 mA
250 mA
STOD13A
200 mA
170 mA
150 mA
STOD03A
STOD13AS
STOD13AM
STOD13CM
STOD03AS
STOD1317B
STOD02
STOD03B
Boost + inverting
Buck + inverting
Boost + LDO
Boost + LDO + inverting
Performance
KEY FACTORS
Soft-start control
A digital soft-start control is implemented during the start-up phase of the DC-DC converter in order to ensure correct start-up procedure, limit
inrush current and over/undershoots of output voltage, and increase battery lifetime. Implementing a soft-start routine eliminates the problems
caused by inrush current, as it allows the current to build up monotonically (smoothly) over a controlled period of time to the required value.
Short-circuit detection (SSD)
SSD functionality detects failed AMOLED panels and safely switches them off. If the panel is not damaged, normal soft-start procedure and
functionality are ensured.
Multiple operating modes
To improve efficiency at very light load, the device works using PSM control, skipping switching cycles to decrease switching losses and
therefore reduce supply current. At light load (up to a few tens of mA), the devices enter discontinuous conduction mode, so the inductor current
does not go negative. When the load current is high, the IC supply current is negligible, and thus PWM control with its smaller ripple voltage is
implemented.
True shutdown
This functionality avoids battery leakage by opening the current path between input and output.
Overload protection
Overload protection is implemented to protect the device when its output is overloaded (a short circuit between the two outputs or between
either output and ground).
Short-circuit protection
Short-circuit protection protects the device from permanent damage when a short circuit occurs, turning off the device.
Programmable output voltages
The negative output voltage can be adjusted to define the operating point of the pixel circuit and restore the brightness of the image. The
negative output voltage levels are selectable within a wide range (steps of 100 mV).
Fast discharge
Both outputs use a fast-discharge function to quickly discharge the remaining output voltage to 0 V, preventing phenomena such as ghosting on
the display during shutdown.
3
TYPICAL EFFICIENCY DIAGRAM
Efficiency (VMID - VO2) versus output current
VINA = VINP = 3.7 V, VO2 = -4.4 V, Tj = 25 °C
Efficiency (%)
95
90
85
80
75
70
65
60
55
0.000
Differential load (A)
0.050
0.100
0.150
0.200
0.250
DEVICE SUMMARY
Package
Topology
description
Input voltage
Positive output
voltage
Negative
output voltage
Maximum
efficiency
Accuracy
positive output
voltage
Accuracy
negative
output voltage
STOD02
VFDFPN 12L
3 x 3 x 0.6
Step-up
and inverting
2.5 V to 4.5 V
4.6 V
-2.3 V to -5.9 V
86%
1.5%
2%
STOD03A
VFDFPN 12L
3 x 3 x 0.6
Step-up
and inverting
2.3 V to 4.5 V
4.6 V
-2.4 V to -5.4 V
86%
1.5%
2%
STOD03B
VFDFPN 12L
3 x 3 x 0.6
Step-up, LDO
and inverting
2.3 V to 4.8 V
4.6 V
-2.4 V to -5.4 V
83%
1.5%
2%
STOD03AS
VFDFPN 12L
3 x 3 x 0.6
Step-up
and inverting
2.5 V to 4.5 V
4.6 V
-2.4 V to -5.4 V
87%
0.8%
1.7%
STOD13A
VFDFPN 12L
3 x 3 x 0.6
Step-up
and inverting
2.5 V to 4.5 V
4.6 V
-2.4 V to -6.4 V
87%
0.8%
1.7%
STOD13AS
VFDFPN 12L
3 x 3 x 0.6
Step-up
and inverting
2.5 V to 4.5 V
4.6 V
-2.4 V to -6.4 V
89%
0.6%
1.4%
STOD13AM
VFDFPN 12L
3 x 3 x 0.6
Step-up
and inverting
2.5 V to 4.5 V
4.6 V
-2.4 V to -5.4 V
89%
0.6%
1.4%
STOD13CM
VFDFPN 12L
3 x 3 x 0.6
Step-up
and inverting
2.5 V to 4.5 V
4.6 V
-1.4 V to -4.4 V
89%
0.5%
0.8%
STOD1317B
VFDFPN 10L
3 x 3 x 0.8
Step-up
and LDO
2.6 V to 4.8 V
6.0 V to 13.0 V
NA
85%
1%
NA
STOD14
VFDFPN 12L
4x4x1
Step-down
and inverting
6 V to 13.0 V
4.6 V
-2.4 V to -6 V
87%
1%
1.4%
Part number
© STMicroelectronics - November 2012- Printed in United Kingdom - All rights reserved
The STMicroelectronics corporate logo is a registered trademark of the STMicroelectronics group of companies
All other names are the property of their respective owners
Order code: BRAMOLED1112
For more information on ST products and solutions, visit www.st.com/amoled