Features
■ Step-up and inverter converters
■ Operating input voltage range from 2.5 V to
4.5 V
■ Synchronous rectification for both DC-DC
converters
■ Minimum 250 mA output current
■ 4.6 V fixed positive output voltage
■ Programmable negative voltage by S
WIRE
from
-2.4 V to -6.4 V at 100 mV steps
■ Typical efficiency 85%
■ Pulse skipping mode in light load condition
■ 1.5 MHz PWM mode control switching
frequency
■ TDMA noise high immunity
■ Enable pin for shutdown mode
■ Low quiescent current in shutdown mode
■ Soft-start with inrush current protection
■ Overtemperature protection
■ Temperature range -40 °C to 85 °C
■ True-shutdown mode
■ Fast outputs discharge circuit after shutdown
■ Short-circuit protection
■ Package DFN12L (3 x 3) 0.6 mm height
Applications
■ Active matrix AMOLED power supply in
portable devices
■ Cellular phones
■ Camcorders and digital still cameras
■ Multimedia players
Table 1. Device summary
STOD13A
250 mA dual DC-DC converter
for powering AMOLED displays
DFN12L (3 x 3 mm)
Description
The STOD13A is a dual DC-DC converter for
AMOLED display panels. It integrates a step-up
and an inverting DC-DC converter making it
particularly suitable for battery operated products,
in which the major concern is overall system
efficiency. It works in pulse skipping mode during
low load conditions and PWM-MODE at 1.5 MHz
frequency for medium/high load conditions. The
high frequency allows the value and size of
external components to be reduced. The Enable
pin allows the device to be turned off, therefore
reducing the current consumption to less than 1
µA. The negative output voltage can be
programmed by an MCU through a dedicated pin
which implements single-wire protocol. Soft-start
with controlled inrush current limit, thermal
shutdown and short-circuit protection are
integrated functions of the device.
Order code Positive voltage Negative voltage Package Packaging
STOD13ATPUR 4.6V -2.4V to -6.4V DFN12L (3 x 3mm) 3000 parts per reel
December 2011 Doc ID 022599 Rev 1 1/24
www.st.com
24
Contents STOD13A
Contents
1 Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6 Detailed description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.1 S
6.1.1 S
6.1.2 S
6.1.3 S
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
WIRE
features and benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
WIRE
protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
WIRE
basic operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
WIRE
6.2 Negative output voltage levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.1 External passive components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.1.1 Inductor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.1.2 Input and output capacitor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.2 Recommended PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8 Detailed description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.1 General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.1.1 Multiple operation modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.1.2 Enable pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1.3 Soft-start and inrush current limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1.4 Undervoltage lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1.5 Overtemperature protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1.6 Short-circuit protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1.7 Fast discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
9 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2/24 Doc ID 022599 Rev 1
STOD13A Contents
10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Doc ID 022599 Rev 1 3/24
Schematic STOD13A
1 Schematic
Figure 1. Application schematic
VBAT
CIN
CREF
S-Wire
EN
FD
VINA
Swire
EN
FD
VREF
L1
VINP
STOD13A
LX1
AGNDPGND
VMID
CMID
VO2
CO2
LX2
L2
AM10430v1
Table 2. Typical external components
Comp. Manufacturer Part number Value Size Ratings
CoilCraft
(1)
L
1
Murata
SEMCO
ABCO
CoilCraft
(2)
L
2
Murata
TOKO
C
IN
C
MID
C
O2
C
REF
1. A 250 mA load can be provided with inductor saturation current as a minimum of 0.9 A.
2. At -6.4 V, a 250 mA load can be provided with inductor saturation current as a minimum of 1.5 A. See Section 7.1.1.
Murata
Taiyo Yuden
Murata
Taiyo Yuden
Murata
Taiyo Yuden
Murata
Taiyo Yuden
LPS4012-472ML
LQH3NPN4R7MJ0
CIG22B4R7MNE
LPF2810T-4R7M
LPS4012-472ML
LQH3NPN4R7MJ0
DFE252012C 1239AS-H-4R7N
GRM219R61A106KE44
LMK212BJ106KD-T
GRM219R61A106KE44
LMK212BJ106KD-T
GRM219R61A106KE44
LMK212BJ106KD-T
GRM185R60J105KE26
JMK107BJ105KK-T
4.7µH
4. 7µH
2 x
10µF
10µF
2 x
10µF
1µF
4.0 x 4.0 x 1.2
3.0 x 3.0 x 1.1
2.5 x 2.0 x 1.0
2.8 x 2.8 x 1.0
4.0 x 4.0 x 1.2
3.0 x 3.0 x 1.1
2.5 x 2.0 x 1.2
0805
0805
0805
0805
0805
0805
0603
0603
±20%, curr. 1.7A, res. 0.175Ω
±20%, curr. 1.1A, res. 0.156Ω
±20%, curr. 1.1A, res. 0.300Ω
±20%, curr. 0.85A, res. 0.33Ω
±20%, curr. 1.7A, res. 0.175Ω
±20%, curr. 1.1A, res. 0.156Ω
±30%, curr. 1.2A, res. 0.252Ω
±10%, X5R, 10V
±10%, X5R, 10V
±10%, X5R, 10V
±10%, X5R, 10V
±10%, X5R, 10V
±10%, X5R, 10V
±10%, X5R, 6.3V
±10%, X5R, 6.3V
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. Inductor
values ranging from 3.3 µH to 6.8 µH can be used together with the STOD13A.
4/24 Doc ID 022599 Rev 1
STOD13A Schematic
Figure 2. Block schematic
Doc ID 022599 Rev 1 5/24
Pin configuration STOD13A
2 Pin configuration
Figure 3. Pin configuration (top view)
Table 3. Pin description
Pin name Pin number Description
Lx
1
1 Boost converter switching node.
PGND 2 Power ground pin.
V
MID
FD 4
AGND 5
V
REF
S
WIRE
EN 8
V
O2
Lx
2
V
IN A
12 Power input supply voltage.
V
IN P
3 Boost converter output voltage.
Fast discharge control pin. When pulled LOW the fast discharge after
shutdown is active. When pulled HIGH the fast discharge is OFF.
Signal ground pin. This pin must be connected to the power ground
layer.
6
Voltage reference output. 1µF bypass capacitor must be connected
between this pin and AGND.
7 Negative voltage setting pin.
Enable control pin. high = converter on; low = converter in shutdown
mode.
9 Inverting converter output voltage.
10 Inverting converter switching node.
11 Analogic input supply voltage.
Exposed
Pad
Internally connected to AGND. Exposed pad must be connected to
ground layers in the PCB layout in order to guarantee proper operation
of the device.
6/24 Doc ID 022599 Rev 1
STOD13A Maximum ratings
3 Maximum ratings
Table 4. Absolute maximum ratings
Symbol Parameter Value Unit
V
, V
INA
EN, S
WIRE
FD Logic input pin - 0.3 to V
ILx
2
Lx
2
V
O2
V
MID
Lx
1
ILx
1
V
REF
P
D
T
ST
T
J
ESD
DC supply voltage - 0.3 to 6 V
INP
Logic input pins - 0.3 to 4.6 V
INA
Inverting converter switching current Internally limited A
Inverting converter switching node voltage - 10 to V
INP
Inverting converter output voltage - 10 to AGND+0.3 V
Step-up converter output voltage -0.3 to 6 V
Step-up converter switching node voltage - 0.3 to V
MID
Step-up converter’s switching current Internally limited A
Reference voltage - 0.3 to 3 V
Power dissipation Internally limited mW
Storage temperature range - 65 to 150 °C
Maximum junction temperature +150 °C
Human body model protection ± 2 kV
Machine body model protection ± 200 V
+0.3 V
+0.3 V
+0.3 V
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 Value Unit
R
thJA
R
thJC
1. The package is mounted on a 4-layer (2S2P) JEDEC board as per JESD51-7.
Thermal resistance junction-ambient 33 °C/W
Thermal resistance junction-case (FR-4 PCB)
(1)
2.12 °C/W
Doc ID 022599 Rev 1 7/24
Electrical characteristics STOD13A
4 Electrical characteristics
TJ = 25 °C, V
C
= 2 x 10 µF, C
O2
INA
= V
= 3.7 V, I
INP
= 1 µF, L1 = L2 = 4.7 µH, V
REF
MID,O2
= 30 mA, C
= 2 x 10 µF, C
IN
= 2 V, V
EN
= 10 µF,
MID,
= 4.6 V, VO2= -4.9 V unless
MID
otherwise specified.
Table 6. Electrical characteristics
Symbol Parameter Test conditions Min. Typ. Max. Unit
General section
V
INA, VINP
UVLO_H Undervoltage lockout HIGH V
UVLO_L Undervoltage lockout LOW V
I_
I
Q_SH
V
EN
V
EN
I
EN
VFD H Fast discharge high threshold
V
FD
fs Switching frequency PWM mode 1.35 1.5 1.65 MHz
D1
D2
V
REF
I
REF
Supply input voltage 2.5 3.7 4.5 V
rising 2.22 2.25 V
INA
Falling 1.9 2.18 V
INA
VI
Input current No load condition 1.7 2.1 mA
Shutdown current VEN=GND; TJ=-40°C to +85°C 1 µA
H Enable high threshold
INA
TJ=-40°C to +85°C
1.2 V
=2.5V to 4.5V,
V
L Enable low threshold 0.4
Enable input current
V
EN=VINA
TJ=-40°C to +85°C
V
INA
TJ=-40°C to +85°C
=4.5V;
=2.5V to 4.5V,
1.2 V
L Fast discharge low threshold 0.4
MAX
MAX
Step-up maximum duty cycle No load 87 %
Inverting maximum duty cycle No load 87 %
=10 to 30mA,
I
Total system efficiency
Reference voltage I
Reference current capability
MID,O2
V
=4.6V, VO2=-4.9V
MID
I
=30 to 150mA, V
MID,O2
V
=-4.9V
O2
=150 to 250mA,
I
MID,O2
=4.6V, VO2=-4.9V
V
MID
=10µA 1.208 1.220 1.232 V
REF
At 98.5% of no load
reference voltage
MID
=4.6V,
100 µA
78 %
85
82
1µA
Step-up converter section
Positive output voltage 4.6 V
=2.9V to 4.5V;
=5mA to 250mA, IO2 no load
=3.4V to 2.9V, I
=10µs
ΔV
V
MID
MID LT
Positive output voltage total
variation
Line transient
V
INA=VINP
I
MID
T
= -40°C to +85°C
J
V
INA,P
T
R=TF
8/24 Doc ID 022599 Rev 1
=100mA;
MID
-0.8 0.8 %
-10 mV
STOD13A Electrical characteristics
Table 6. Electrical characteristics (continued)
Symbol Parameter Test conditions Min. Typ. Max. Unit
I
ΔV
MID T
Load transient response
=3 to 30mA and I
MID
3mA, T
=10 to 100mA and I
I
MID
R=TF
=150µs
to 10mA, TR=TF=150µs
MID
=30 to
=100
MID
±20 mV
±25 mV
Undershoot/overshoot
TDMA Noise
I
MID MAX
I-L
1MAX
R
DSON
R
DSON
Static variation between low
and high V
IN
Maximum output current V
Step-up inductor peak current V
P-channel static drain-source
P1
ON resistance
N-channel static drain-source
N1
ON resistance
Inverting converter section
Negative output voltage range
V
O2
Negative output voltage -4.9 V
Negative output voltage total
variation
ΔV
ΔV
O2 LT
O2 T
Line transient
Load transient response
Undershoot/overshoot
TDMA Noise
I
O2 MAX
I-L
2MAX
R
DSON
R
DSON
Static variation between low
and high V
IN
Maximum output current V
Inverting peak current VO2 below 10% nominal value -1.43 -1.17 A
P-channel static drain-source
P2
ON resistance
N-channel Static Drain-source
N2
ON resistance
level
level
±20
I
=10 to 100mA; IO2 no load
MID
=2.9V to 4.5V 250 mA
INA,P
10% below nominal value 1.08 1.32 A
MID
V
INA=VINP
V
INA=VINP
=3.7V, I
=3.7V, I
SW-P1
SW-N1
41 different values set by the
pin (see Section 6.1.2)
S
WIRE
V
INA=VINP
IO2=5mA to 250mA, I
=-40°C to +85°C
T
J
V
INA,P
=2.9V to 4.5V;
MID
=3.4V to 2.9V, IO2=100mA,
TR=TF=10µs
I
=3 to 30mA and IO2=30 to
O2
3mA, TR=TF=150µs
=10 to 100mA and IO2=100 to
I
O2
10mA, T
R=TF
=150µs
(1)
4
=100mA 1.0 2.0 Ω
=100mA 0.4 1.0 Ω
-6.4 -2.4 V
no load
-1.7 1.7 %
+10 mV
± 20 mV
± 25 mV
± 20 mV
IO2=10 to 100mA; I
=2.9V to 4.5V -250 mA
INA,P
V
INA=VINP
V
INA=VINP
=3.7V, I
=3.7V, I
MID
SW-P2
SW-N2
no load
(1)
5
=100mA 0.42 0.8 Ω
=100mA 0.43 0.8 Ω
mV
Thermal shutdown
OTP Overtemperature protection 140 °C
OTP
HYST
Overtemperature protection
hysteresis
15 °C
Doc ID 022599 Rev 1 9/24
Electrical characteristics STOD13A
Table 6. Electrical characteristics (continued)
Symbol Parameter Test conditions Min. Typ. Max. Unit
Discharge resistor
1. V
R
DIS
T
DIS
INA,P
Resistor value No load, EN=SW=FD=Low 400 Ω
Discharge time
= 4.2 to 3.7 V, 3.7 to 3.2 V, 3.4 to 2.9 V, f = 200 Hz; t
No load, EN=SW=FD=Low, V
VO2 at 10% of nominal value
= 3.65 ms; t
ON
= 1.25 ms; TR = TF = 10 µs, pulse signal.
OFF
MID
10 ms
10/24 Doc ID 022599 Rev 1
STOD13A Typical performance characteristics
5 Typical performance characteristics
V
= V
INA
the tests below.
Figure 4. Maximum power output vs. input
voltage (V
= 3.7 V, VO2 = - 4.9 V, TJ = 25°C; see Ta bl e 1 for external components used in
INP
Figure 5. Efficiency vs. output current
= V
INA
= 2.9 to 4.2 V)
INP
V
= V
INA
= 3.3 to 4.2 V, I
INP
= 10 to 250 mA
MID,O2
Figure 6. Efficiency vs. inductor Figure 7. Soft-start and inrush current (no
I
= 10 to 250 mA, L1 = L2
MID,O2
Figure 8. Fast discharge Figure 9. Switching and output waveforms
load)
No load, EN = SW = FD = Low
V
= V
INA
= 2.9 V, I
INP
= 250 mA, TJ = 85 °C
MID,O2
Doc ID 022599 Rev 1 11/24
Typical performance characteristics STOD13A
Figure 10. Step-up CCM operation Figure 11. Inverting CCM operation
I
= 100 mA
MID
IO2 = 100 mA
12/24 Doc ID 022599 Rev 1
STOD13A Detailed description
6 Detailed description
6.1 S
● Protocol: to digitally communicate over a single cable with single-wire components
● Single-wire's 3 components:
1. an external MCU
2. wiring and associated connectors
3. the STOD13A device with a dedicated single-wire pin.
6.1.1 S
● Fully digital signal
● No handshake needed
● Protection against glitches and spikes though an internal low pass filter acting on both
● Uses a single wire (plus analog ground) to accomplish both communication and power
● Simplified design with an interface protocol that supplies control and signaling over a
6.1.2 S
● Single-wire protocol uses conventional CMOS/TTL logic levels (maximum 0.6 V for
● Both master (MCU) and slave (STOD13A) are configured to permit bit sequential data
● 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
WIRE
features and benefits
WIRE
rising and falling edges
control transmission
single-wire connection to set the output voltages.
protocol
WIRE
logic “zero” and a minimum 1.2 V for logic “one”) with operation specified over a supply
voltage range of 2.5 V to 4.5 V
to flow only in one direction at a time; master initiates and controls the device
integrated in the master and is asserted valid within a frequency range of 250 kHz
(maximum).
6.1.3 S
basic operations
WIRE
● The negative output voltage levels are selectable within a wide range (steps of 100 mV)
● The device can be enabled / disabled via S
Doc ID 022599 Rev 1 13/24
in combination with the Enable pin.
WIRE
Detailed description STOD13A
6.2 Negative output voltage levels
Table 7. Negative output voltage levels
Pulse V
O2
Pulse V
O2
Pulse V
O2
Pulse V
1 -6.4 11 -5.4 21 -4.4 31 -3.4
2 -6.3 12 -5.3 22 -4.3 32 -3.3
3 -6.2 13 -5.2 23 -4.2 33 -3.2
4 -6.1 14 -5.1 24 -4.1 34 -3.1
5 -6.0 15 -5.0 25 -4.0 35 -3.0
6-5.916
(1)
-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
41 -2.4
1. Default value.
Table 8. Enable and S
Enable S
operation table
WIRE
(1)
WIRE
Action
Low Low Device off
O2
Low High Negative output set by S
High Low Default negative output voltage
High High Default negative output voltage
1. The Enable pin must be set to AGND while using the S
Table 9. Fast Discharge operation table
FD pin Action
Low Fast discharge active after IC shutdown
High No fast discharge function
The FD function is only controlled by the FD pin. It is not related to the enable block.
WIRE
WIRE
function.
14/24 Doc ID 022599 Rev 1
STOD13A Application information
7 Application information
7.1 External passive components
7.1.1 Inductor selection
Magnetic shielded low ESR power inductors must be chosen as the key passive
components for switching converters.
For the step-up converter an inductance between 4.7 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 the right inductor according to the maximum current the
inductor can handle to avoid saturation. The step-up and the inverting peak current can be
calculated as follows:
Equation 1
IV
×
I
−
=
BOOSTPEAK
OUTMID
VIN1
×η
+
MIN
MID
−×
×××
)VINV(VIN
MINMIDMIN
1LfsV2
Equation 2
x-
x-
)2(
IVOVIN
)2(
MIN
MIN
IVOVIN
=
I
I
-
-
INVERTINGPEAK
INVERTINGPEAK
=
x
x
η
η
2
VIN
2
VIN
where
V
: step-up output voltage, fixed at 4.6 V;
MID
V
: inverting output voltage including sign (minimum value is the absolute maximum
O2
value);
I
: output current for both DC-DC converters;
O
V
: input voltage for the STOD03A;
IN
f
: switching frequency. Use the minimum value of 1.35 MHz for the worst case;
s
η1: efficiency of step-up converter. Typical value is 0.70;
η2: efficiency of inverting converter. Typical value is 0.60.
The negative output voltage can be set via S
WIRE
current, at the maximum load condition, increases. A proper inductor, with a saturation
current as a minimum of 1.5 A, is preferred.
7.1.2 Input and output capacitor selection
x
x
2
VOVIN
2
VOVIN
OUTMINMIN
OUTMINMIN
+
+
x
x
MINMIN
MINMIN
xx-
xx-
2)2(2
LfsVINVO
2)2(2
MINMIN
MINMIN
LfsVINVO
at - 6.4 V. Accordingly, the inductor peak
It is recommended to use X5R or X7R low ESR ceramic capacitors as input and output
capacitors in order to filter any disturbance present in the input line and to obtain stable
operation for the two switching converters. A minimum real capacitance value of 6 µF must
be guaranteed for C
variation and DC polarization, a 10 µF 10 V ±10% capacitor as C
±10% as C
, can be used to achieve the required 6 µF.
O2
and CO2 in all conditions. Considering tolerance, temperature
MID
Doc ID 022599 Rev 1 15/24
and 2 x 10 µF 10 V
MID
Application information STOD13A
7.2 Recommended PCB layout
The STOD13A is high frequency power switching device and therefore requires a proper
PCB layout in order to obtain the necessary stability and optimize line/load regulation and
output voltage ripple.
Analog input (V
at the C
pad only. The input capacitor must be as close as possible to the IC.
IN
) and power input (V
INA
) must be kept separated and connected together
INP
In order to minimize the ground noise, a common ground node for power ground and a
different one for analog ground must be used. In the recommended layout, the AGND node
is placed close to C
ground while the PGND node is centered at CIN ground. They are
REF
connected by a separated layer routing on the bottom through vias.
The exposed pad is connected to AGND through vias.
Figure 12. Top layer and silk-screen (top view, not to scale)
16/24 Doc ID 022599 Rev 1
STOD13A Application information
Figure 13. Bottom layer (top view, not to scale)
Doc ID 022599 Rev 1 17/24
Detailed description STOD13A
8 Detailed description
8.1 General description
The STOD13A is a high efficiency dual DC-DC converter which integrates a step-up 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 each of the two DC-DC 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 saturation
of the coils.
The STOD13A implements a power saving technique in order to maintain high efficiency at
very light load and it switches to PWM operation as the load increases in order to guarantee
the best dynamic performances and low noise operation.
The STOD13A 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.
8.1.1 Multiple operation modes
Both the step-up and the inverting stage of the STOD13A operate in three different modes:
pulse skipping (PSM), discontinuous conduction mode (DCM) and continuous conduction
mode (CCM). It switches automatically between the three modes according to input voltage,
output current, and output voltage conditions.
Pulse skipping operation:
The STOD13A works in pulse skipping mode when the load current is below a few mA.
The load current level at which this way of operation occurs depends on input voltage only
for the step-up converter and on input voltage and negative output voltage (VO2) for the
inverting converter.
Discontinuous conduction mode:
When the load increases above some tens of mA, the STOD13A enters DCM operation.
In order to obtain this type of operation the controller must avoid the inductor current going
negative. The discontinuous mode detector (DMD) blocks sense the voltage across the
synchronous rectifiers (P1B for the step-up and N2 for the inverting) and turn off the
switches when the voltage crosses a defined threshold which, in turn, represents a certain
current in the inductor. This current can vary according to the slope of the inductor current
which depends on input voltage, inductance value, and output voltage.
Continuous conduction mode:
At medium/high output loads, the STOD13A enters in full CCM at constant switching
frequency mode for each of the two DC-DC converters.
18/24 Doc ID 022599 Rev 1
STOD13A Detailed description
8.1.2 Enable pin
The device operates when the EN pin is set high. If the EN pin is set low, the device stops
switching, and all the internal blocks are turned off. In this condition the current drawn from
V
INP/VINA
is below 1 µA in the whole temperature range. 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.
8.1.3 Soft-start and inrush current limiting
After the EN pin is pulled high, or after a suitable voltage is applied to V
device initiates the startup phase. As a first step, the C
switch implements a current limiting technique in order to keep the charge current below
400 mA. This avoids the battery overloading during startup. After V
voltage level, the P1B switch is fully turned on and the soft-start procedure for the step-up is
started.
After around 2 ms the soft-start for the inverting is started. The positive and negative
voltages are under regulation at around 6ms after the EN pin is asserted high.
8.1.4 Undervoltage lockout
The undervoltage lockout function avoids improper operation of the STOD13A 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 of 50 mV avoids unstable operation when the
input voltage is close to the UVLO threshold.
8.1.5 Overtemperature protection
An internal temperature sensor continuously monitors the IC junction temperature. If the IC
temperature exceeds 140 °C, typical, the device stops operating. As soon as the
temperature falls below 125 °C, typical, normal operation is restored.
8.1.6 Short-circuit protection
, V
capacitor is charged, the P1B
MID
INP
reaches the V
MID
and EN the
INA
INP
When short-circuit occurs, the device is able to detect the voltage difference between VIN
and V
. Overshoots are limited, decreasing the inductor current. After that, the output
OUT
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. During startup the shortcircuit protection is active.
8.1.7 Fast discharge
When ENABLE turns from high to low level and the FD pin is low, the device goes into
shutdown mode and LX1 and LX2 stop switching. Then, the discharge switch between V
and V
voltage and negative output voltage. When the output voltages are discharged to 0 V, the
switches turn off and the outputs are high impedance. When the FD pin is high, the fast
discharge after shutdown is off.
and the switch between VO2 and GND turn on and discharge the positive output
IN
MID
Doc ID 022599 Rev 1 19/24
Package mechanical data STOD13A
9 Package mechanical data
In order to meet environmental requirements, ST offers these devices in different grades of
ECOPACK
specifications, grade definitions, and product status are available at:
ECOPACK is an ST registered trademark.
®
packages, depending on their level of environmental compliance. ECOPACK
www.st.com.
20/24 Doc ID 022599 Rev 1
STOD13A Package mechanical data
DFN12L (3 x 3 x 0.6 mm) mechanical data
mm. inch.
Dim.
Min. Typ. Max. Min. Typ. Max.
A 0.51 0.55 0.60 0.020 0.022 0.024
A1 0 0.02 0.05 0 0.001 0.002
A3 0.20 0.008
b 0.18 0.25 0.30 0.007 0.010 0.012
D2.85 33.15 0.112 0.118 0.124
D2 1.87 2.02 2.12 0.074 0.080 0.083
E2.85 33.15 0.112 0.118 0.124
E2 1.06 1.21 1.31 0.042 0.048 0.052
e 0.45 0.018
L0.30 0.40 0.50 0.012 0.016 0.020
8085116/A
Doc ID 022599 Rev 1 21/24
Package mechanical data STOD13A
Figure 14. DFN12L (3 x 3 mm) footprint recommended data
22/24 Doc ID 022599 Rev 1
STOD13A Revision history
10 Revision history
Table 10. Document revision history
Date Revision Changes
14-Dec-2011 1 Initial release.
Doc ID 022599 Rev 1 23/24
STOD13A
Please Read Carefully:
Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the
right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any
time, without notice.
All ST products are sold pursuant to ST’s terms and conditions of sale.
Purchasers are solely responsible for the choice, selection and use of the ST products and services described herein, and ST assumes no
liability whatsoever relating to the choice, selection or use of the ST products and services described herein.
No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. If any part of this
document refers to any third party products or services it shall not be deemed a license grant by ST for the use of such third party products
or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoever of such
third party products or services or any intellectual property contained therein.
UNLESS OTHERWISE SET FORTH IN ST’S TERMS AND CONDITIONS OF SALE ST DISCLAIMS ANY EXPRESS OR IMPLIED
WARRANTY WITH RESPECT TO THE USE AND/OR SALE OF ST PRODUCTS INCLUDING WITHOUT LIMITATION IMPLIED
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS
OF ANY JURISDICTION), OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT.
UNLESS EXPRESSLY APPROVED IN WRITING BY TWO AUTHORIZED ST REPRESENTATIVES, ST PRODUCTS ARE NOT
RECOMMENDED, AUTHORIZED OR WARRANTED FOR USE IN MILITARY, AIR CRAFT, SPACE, LIFE SAVING, OR LIFE SUSTAINING
APPLICATIONS, NOR IN PRODUCTS OR SYSTEMS WHERE FAILURE OR MALFUNCTION MAY RESULT IN PERSONAL INJURY,
DEATH, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE. ST PRODUCTS WHICH ARE NOT SPECIFIED AS "AUTOMOTIVE
GRADE" MAY ONLY BE USED IN AUTOMOTIVE APPLICATIONS AT USER’S OWN RISK.
Resale of ST products with provisions different from the statements and/or technical features set forth in this document shall immediately void
any warranty granted by ST for the ST product or service described herein and shall not create or extend in any manner whatsoever, any
liability of ST.
ST and the ST logo are trademarks or registered trademarks of ST in various countries.
Information in this document supersedes and replaces all information previously supplied.
The ST logo is a registered trademark of STMicroelectronics. All other names are the property of their respective owners.
© 2011 STMicroelectronics - All rights reserved
STMicroelectronics group of companies
Australia - Belgium - Brazil - Canada - China - Czech Republic - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan -
Malaysia - Malta - Morocco - Philippines - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States of America
www.st.com
24/24 Doc ID 022599 Rev 1
Loading...