150 mA dual DC-DC converter with LDO
Features
■ Step-up with LDO and inverter converters
■ Operating input voltage range from 2.3 V to
4.8 V
■ Synchronous rectification for both DC-DC
converters
■ Minimum 150 mA output current
■ LDO post regulator for 4.6 V fixed positive
output to provide line and load transient
response with minimum output voltage ripple
■ Programmable negative voltage by S
- 2.4 V to -5.4 V at 100 mV steps
■ Typical efficiency: 82%
■ Pulse skipping mode in light load condition
■ 1.5 MHz PWM mode control switching
frequency
■ 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
■ Package DFN (3 x 3) 12 leads 0.6 mm height
Applications
■ Active matrix AMOLED power supply in
portable devices
■ Cellular phones
■ Camcorders and digital still cameras
■ Multimedia players
WIRE
from
STOD03B
for powering AMOLED displays
DFN12L (3 x 3 mm)
Description
The STOD03B 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 the 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 4.6 V
output is provided by an LDO in cascade with the
step-up converter. This allows a noise and ripple
free positive output for the AMOLED panel to
provide stable picture quality. 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 and thermal
shutdown are integrated functions of the device.
Table 1. Device summary
Order code Positive voltage Negative voltage Package Packaging
STOD03BTPUR 4.6V - 2.4V to - 5.4V DFN12L (3 x 3mm) 3000 parts per reel
December 2011 Doc ID 022613 Rev 1 1/22
www.st.com
22
Contents STOD03B
Contents
1 Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
6 Detailed description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1 S
6.1.1 S
6.1.2 S
6.1.3 S
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
WIRE
features and benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
WIRE
protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
WIRE
basic operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
WIRE
6.2 Negative output voltage levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
S
6.3 Enable and
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
WIRE
7 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1 External passive components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1.1 Inductor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1.2 Input and output capacitor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
7.2 Recommended PCB layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8 Detailed description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
8.1 General description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
8.1.1 Multiple operation modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
8.1.2 Enable pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.1.3 Soft-start and inrush current limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.1.4 Undervoltage lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.1.5 Overtemperature protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
9 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
10 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2/22 Doc ID 022613 Rev 1
STOD03B Schematic
1 Schematic
Figure 1. Application schematic
VBAT
CIN
S-Wire
EN
VINA
Swire
EN
L1
VINP
STOD03B
LX1
VMID
CMID
VO1
CO1
CREF
Table 2. Typical external components
VREF
AGNDPGND
LX2
VO2
CO2
L2
AM10428v1
Comp. Manufacturer Part number Value Size Ratings
COILCRAFT
MURATA
(1)
L
1
SEMCO
ABCO
ABCO
COILCRAFT
(2)
L
2
MURATA
TOKO
ABCO
C
IN
C
O1
MURATA
TAIYO YUDEN
MURATA
TAIYO YUDEN
LPS4012-472ML
LQH3NPN4R7MJ0
CIG22B4R7MNE
LPF2810T-4R7M
LPF2807T-4R7M
LPS4012-472ML
LQH3NPN4R7MJ0
DFE252012C 1239AS-H-
4R7N
LPF2807T-4R7M
GRM219R61A106KE44
LMK212BJ106KD-T
GRM219R61A106KE44
LMK212BJ106KD-T
4.7µH
4.7µH
10µF
10µF
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
2.8 x 2.8 x 0.7
4.0 x 4.0 x 1.2
3.0 x 3.0 x 1.1
2.5 x 2.0 x 1.2
2.8 x 2.8 x 0.7
0805
0805
0805
0805
±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. 0.70A, res. 0.44Ω
±20%, curr. 1.7A, res. 0.175Ω
±20%, curr. 1.1A, res. 0.156Ω
±30%, curr. 1.2A, res. 0.252Ω
±20%, curr. 0.70A, res. 0.44Ω
±10%, X5R, 10V
±10%, X5R, 10V
±10%, X5R, 10V
±10%, X5R, 10V
C
O2
MURATA
TAIYO YUDEN
GRM219R61A106KE44
LMK212BJ106KD-T
10µF
0805
0805
±10%, X5R, 10V
±10%, X5R, 10V
Doc ID 022613 Rev 1 3/22
Schematic STOD03B
Table 2. Typical external components (continued)
Comp. Manufacturer Part number Value Size Ratings
C
C
MID
REF
MURATA
TAIYO YUDEN
MURATA
TAIYO YUDEN
GRM219R61A106KE44
LMK212BJ106KD-T
GRM185R60J105KE26
JMK107BJ105KK-T
10µF
1µF
0805
0805
0805
0805
±10%, X5R, 10V
±10%, X5R, 10V
±10%, X5R, 10V
±10%, X5R, 10V
1. A 200 mA load can be provided with inductor saturation current as a minimum of 0.6 A.
2. For V
in a range between - 4.9 V to -5.4 V, a load current of 150 mA to 200 mA can be provided using inductors with a
O2
saturation current as a minimum of 1 A. See Section 7.1.1.
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 STOD03B.
Figure 2. Block schematic
VINA
S-WIRE
VINP
UVLO
LOGIC CON TROL
OTP
S-WIRE
RING
KILLER
STEP-UP
CONTROL
LX1
DMD
FAST
DISCHARGE
LDO
VMID
VO1
INVERT ING
CONTROL
OSC
VINP
LX2
DMD
FAST
DISCHARGE
EN
VREF
AGND
PGND
VREF
4/22 Doc ID 022613 Rev 1
VREF
S-wire
control
VO2
AM10429v1
STOD03B Pin configuration
2 Pin configuration
Figure 3. Pin configuration (top view)
Table 3. Pin description
Pin name Pin n° Description
Lx
1
1 Boost converter switching node
PGND 2 Power ground pin
V
MID
V
O1
3 Step-up converter output voltage (4.9V)
4 4.6V fixed LDO output
AGND 5 Signal ground pin. This pin must be connected to the power ground layer
V
S
REF
WIRE
6
7 Negative voltage setting pin.
EN 8
V
O2
Lx
2
V
IN A
V
12 Power input supply voltage
iN P
9 Inverting converter output voltage
10 Inverting converter switching node
11 Analogic input supply voltage
Exposed
pad
1. No pull-up/pull-down resistors are needed.
Voltage reference output. 1µF bypass capacitor must be connected
between this pin and AGND
Enable control pin. High 1
converter on; low or floating = converter in shutdown mode
(1)
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
Doc ID 022613 Rev 1 5/22
Maximum ratings STOD03B
3 Maximum ratings
Table 4. Absolute maximum ratings
Symbol Parameter Value Unit
V
INA
EN, S
IL
L
V
V
O1, VMID
L
IL
V
P
T
ESD
, V
WIRE
X2
X2
O2
X1
X1
REF
D
STG
T
J
DC supply voltage -0.3 to 6 V
INP
Logic input pins -0.3 to 4.6 V
Inverting converter switching current Internally limited A
Inverting converter switching node voltage -10 to V
+0.3 V
INP
Inverting converter output voltage -10 to AGND+0.3 V
LDO and step-up converter output voltage -0.3 to 6 V
Step-up converter switching node voltage -0.3 to V
+0.3 V
MID
Step-up converter 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 ±
2kV
Machine Body Model Protection ± 200 kV
Note: Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these condition 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
6/22 Doc ID 022613 Rev 1
STOD03B Electrical characteristics
4 Electrical characteristics
TJ = 25 °C, V
C
= 2 x10 µF, C
O2
V
= -4.9 V unless otherwise specified.
O2
Table 6. Electrical characteristics
INA
= V
= 3.7 V, I
INP
= 1 µF, L1 = L2 = 4.7 µH, VEN = 2 V, V
REF
= 30 mA, CIN = 2 x10 µF, C
O1,2
= 2 x10 µF, CO1 = 10 µF,
MID
= 4.9 V, VO1 = 4.6 V,
MID
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_V
I
Q_SH
V
EN
V
EN
I
EN
f
S
D1
MAX
D2
MAX
Supply input voltage 2.3 4.8 V
rising 2.22 2.25 V
INA
falling 1.9 2.18 V
INA
Input current
I
Shutdown current
H Enable high threshold
L Enable low threshold 0.4
Enable input current
No load condition (sum of
and V
V
INA
=GND (sum of V
V
EN
V
); TJ=-40°C to +85°C;
INP
V
=2.3V to 4.8V,
INA
INP
)
and
INA
TJ=-40°C to +85°C;
V
EN=VINA
=-40°C to +85°C;
T
J
=4.8V;
1.2
1.3 1.7 mA
1µA
1µA
Switching frequency PWM mode 1.35 1.5 1.65 MHz
Step-up maximum duty cycle No load 87 %
Inverting maximum duty cycle No load 87 %
I
=10 to 30mA,
O1,O2
VO1=4.6V, VO2=-4.9V
75 %
η Total system efficiency
I
=30 to 150mA,
V
I
REF
REF
Voltage reference I
Voltage reference current
capability
O1,O2
V
=4.6V, VO2=-4.9V
O1
=10µA 1.195 1.207 1.219 V
REF
At 98.5% of no load
reference voltage
100 µA
82 %
OTP Overtemperature protection 140 °C
V
OTP
HYST
Overtemperature protection
hysteresis
Positive output section
Positive voltage total variation
Line transient
Load transient regulation
ΔV
ΔV
V
O1LT
O1
O1T
15 °C
V
INA=VINP
=-40°C to +85°C; IO1=5mA
T
J
=2.3V to 4.8V;
4.554 4.6 4.646 V
to 150mA, IO2 no load
=3.5V to 3.0V,
V
INA,P
=100mA; TR=TF=50µs
I
O1
=3 to 30mA and IO1=30 to
I
O1
3mA, TR=TF=150µs
-12 mV
±20 mV
Doc ID 022613 Rev 1 7/22
Electrical characteristics STOD03B
Table 6. Electrical characteristics (continued)
Symbol Parameter Test conditions Min. Typ. Max Unit
=5 to 100mA; IO2 no load
I
TDMA Noise TDMA noise immunity
(1)
O1
±20 mV
I
O1 MAX
Max. output current V
Positive voltage total variation
V
MID
Temperature accuracy
Step-up inductor peak
current
P-channel Static Drain-
P1
source On resistance
N-channel Static Drain-
N1
source On resistance
R
R
I-L
1MAX
DSON
DSON
Negative output
Negative output voltage
range
Negative output voltage total
V
O2
variation on default value
Temperature accuracy
ΔV
O2LT
Line transient
Load transient regulation
ΔV
O2T
Load transient regulation
TDMA Noise TDMA noise immunity I
I
O2 MAX
I-L
2MAX
Maximum output current V
Inverting peak current
=2.9V to 4.8V 150 mA
INA,P
V
INA=VINP
I
MID
=2.9V to 4.8V;
=5mA to 150mA;
4.8 4.9 5.0 V
IO2 no load; TJ=25°C
V
INA=VINP
I
O2
=3.7V; I
MID
no load; TJ=-40 to
=5mA;
-05 0.5 %
+85°C;
V
10% below nominal
MID
value
V
INA=VINP
I
SW-P1
V
INA=VINP
I
SW-P1
=3.7V,
=100mA
=3.7V,
=100mA
31 different values set by the
S
pin (see S
WIRE
V
INA=VINP
=25°C; IO2=5mA to
T
J
=2.9V to 4.8V;
WIRE
)
11.1A
1.0 1.6 Ω
0.4 0.7 Ω
-5.4 -2.4 V
-4.97 -4.9 -4.83 V
150mA, IO1 no load
V
INA=VINP
I
O2
=3.7V; IO2=5mA;
no load;
-0.5 0.5 %
TJ=-40°C to +85°C
=3.5V to 3.0V,
V
INA,P
=100mA, TR=TF=50µs
I
O2
=3 to 30mA and IO2=30 to
I
O2
3mA, T
I
=10 to 100mA and IO2=100
O2
to 10mA, T
=5 to 100mA; IO1 no load ±25 mV
O2
INA,P
below 10% of nominal
V
O2
value
=150µs
R=TF
=150µs
R=TF
=2.9V to 4.8V -150 mA
-1.2 -0.9 A
+12 mV
±20 mV
±25 mV
R
R
1. V
DSON
DSON
INA,P
source On resistance
N-channel Static Drain-
N2
source On resistance
= 4.2 to 3.7 V, 3.7 to 3.2 V, 3.4 to 2.9 V, f = 200 Hz, t
P-channel Static Drain-
P2
V
INA=VINP
I
SW-P2
V
INA=VINP
I
SW-P2
=3.7V;
=100mA
=3.7V;
=100mA
ON
= 3.65 ms, t
8/22 Doc ID 022613 Rev 1
0.42 0.8 Ω
0.43 0.8 Ω
= 1.25 ms, TR = TF = 50 µs, pulse signal.
OFF
STOD03B Typical performance characteristics
5 Typical performance characteristics
V
= -4.9 V; TJ = 25 °C; See Ta bl e 1 . for external components used in the tests below.
O2
Figure 4. Max power output vs. V
Figure 6. Positive output operation Figure 7. Negative output operation
IN
Figure 5. Efficiency vs. output current
IO1 = 100 mA
Figure 8. Soft-start inrush current Figure 9. Output current vs. input voltage
IO = 200 mA, V
= - 4.9 V
O2
IO2 = 100 mA
V
= V
INA
INAP
= 2.3 to 4.8 V, VO1 = 4.6 V
Doc ID 022613 Rev 1 9/22
Detailed description STOD03B
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. STOD03B 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 falling
● Uses a single wire (plus analog ground) to accomplish both communication and power
● Simplify 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 (STOD03B) 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
edge
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 2.3 V to 4.8 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
● The negative output voltage levels are selectable within a wide range (steps of 100 mV)
● The device can be enabled / disabled via S
10/22 Doc ID 022613 Rev 1
basic operations
WIRE
in combination with the Enable pin.
WIRE
STOD03B Detailed description
6.2 Negative output voltage levels
Table 7. Default output voltage
Pulse V
O2
1 -5.411-4.421-3.4
2 -5.312-4.322-3.3
3 -5.213-4.223-3.2
4 -5.114-4.124-3.1
5 -5.015-4.025-3.0
(1)
6
-4.9 16 -3.9 26 -2.9
7 -4.817-3.827-2.8
8 -4.718-3.728-2.7
9 -4.619-3.629-2.6
10 -4.5 20 -3.5 30 -2.5
1. Default value.
6.3 Enable and S
WIRE
Pulse V
O2
Pulse V
31 -2.4
O2
Table 8. EN and S
operation table
WIRE
(1)
Enable S
Low Low Device off
Low High Negative output voltage 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
WIRE
WIRE
Action
WIRE
function.
Doc ID 022613 Rev 1 11/22
Application information STOD03B
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
MIN
xI)2VOVIN(
OUTMINMIN
+
2VOVIN
×
MINMIN
2Lfs)VIN2VO(2
MINMIN
××−×
I
−
INVERTINGPEAK
=
−
VIN2
×η
where
V
: step-up output voltage, fixed at 4.9 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 of STOD03B;
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
at -5.4 V. Accordingly, the inductor peak
WIRE
current, at the maximum load condition, increases. A proper inductor, with a saturation
current as a minimum of 1 A, is preferred.
STOD03B is capable of supplying a load current from 150 mA to 200 mA. Inductors with a
saturation current as a minimum of 1 A must be selected.
12/22 Doc ID 022613 Rev 1
STOD03B Application information
7.1.2 Input and output capacitor selection
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, 2 x 10 µF, 10 V ±10% as C
as C
and 2 x 10 µF 10 V ±10% as CO2 can be used to achieve the needed 6 µF.
O1
, CO1 and CO2 in all conditions. Considering tolerance, temperature
MID
, a 10 µF 10V ±10% capacitor
MID
7.2 Recommended PCB layout
The STOD03B is a 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 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 connected
REF
by a separated layer routing on the bottom through vias.
The exposed pad is connected to AGND through vias.
Figure 10. Top layer and top silk-screen (top view, not to scale)
Doc ID 022613 Rev 1 13/22
Application information STOD03B
Figure 11. Bottom layer and silk-screen (top view, not to scale)
14/22 Doc ID 022613 Rev 1
STOD03B Detailed description
8 Detailed description
8.1 General description
The STOD03B is a high efficiency dual DC-DC converter which integrates a step-up with an
LDO and inverting power stages 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.
This topology of a boost followed by an LDO regulator offers an efficient ripple reduction
solution for loads up to 200 mA. 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 STOD03B 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 performance
and low noise operation. The STOD03B avoids battery leakage thanks to the true-shutdown
feature and it is self protected by 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 STOD03B operate in three different modes:
pulse skipping mode (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 STOD03B works in pulse skipping mode when the load current is below a few mA.
The load current level at which this way of operating occurs depends on input voltage only
for the step-up converter and on input voltage and negative output voltage (V
inverting converter.
) for the
O2
Discontinuous conduction mode:
When the load increases above some tens of mA, the STOD03B 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 STOD03B enters full CCM at constant switching
frequency mode for each of the two DC-DC converters.
Doc ID 022613 Rev 1 15/22
Detailed description STOD03B
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 by around 6 ms after the EN pin is asserted high.
8.1.4 Undervoltage lockout
The undervoltage lockout function avoids improper operation of the STOD03B 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.
, V
capacitor is charged and the P1B
MID
INP
reaches the V
MID
and EN, the
INA
INP
16/22 Doc ID 022613 Rev 1
STOD03B Package mechanical data
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:
is an ST trademark.
®
packages, depending on their level of environmental compliance. ECOPACK
www.st.com. ECOPACK
Doc ID 022613 Rev 1 17/22
Package mechanical data STOD03B
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
18/22 Doc ID 022613 Rev 1
8085116/A
STOD03B Package mechanical data
Tape & reel QFNxx/DFNxx (3x3) mechanical data
mm. inch
DIM.
MIN. TYP MAX. MIN. TYP. MAX.
A 330 12.992
C 12.8 13.2 0.504 0.519
D 20.2 0.795
N 99 101 3.898 3.976
T 14.4 0.567
Ao 3.3 0.130
Bo 3.3 0.130
Ko 1.1 0.043
Po 4 0.157
P 8 0.315
Doc ID 022613 Rev 1 19/22
Package mechanical data STOD03B
Figure 12. DFN12L (3 x 3 mm) footprint recommended data
20/22 Doc ID 022613 Rev 1
STOD03B Revision history
10 Revision history
Table 9. Document revision history
Date Revision Changes
19-Dec-2011 1 Initial release.
Doc ID 022613 Rev 1 21/22
STOD03B
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