Datasheet

0
0.02
0.04
0.06
0.08
0.10
0.12
0.14
9
10 11 12 13 14 15
Vo1 − Output Voltage − V
− Output Current − AI
O
Vo3 = 18 V (Doubler Mode)
T
A
= 25°C
T
A
= 85°C
T
A
= −40°C
0
0.02
0.04
0.06
0.08
0.10
0.12
9
10 11 12 13 14 15
Vo1 − Output Voltage − V
− Output Current − AI
O
Vo3 = 28 V (Tripler Mode)
T
A
= 25°C
T
A
= 85°C
T
A
= −40°C
0
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
8.8 9.8
10.8 11.8 12.8 13.8 14.8
Vo1 − Output Voltage − V
− Output Current − AI
O
Vo2 = −8 V
T
A
= −40°C
T
A
= 25°C
T
A
= 85°C
Vo1
5 V/div
V
I
= 3.3 V
V
O
= 10 V,
500 µs/div
Vo2
5 V/div
Vo3
10 V/div
Vo1
5 V/div
V
I
= 3.3 V
V
O
= 10 V,
I
O
= 300 mA
500 µs/div
I
I
500
mA/div
TPS65140, TPS65141
TPS65145
SLVS497E –SEPTEMBER 2003–REVISED NOVEMBER 2012 www.ti.com
TYPICAL CHARACTERISTICS (continued)
POWER-UP SEQUENCING SOFT START V
O
1 V
O
2 MAXIMUM LOAD CURRENT
Figure 10. Figure 11. Figure 12.
V
O
3 MAXIMUM LOAD CURRENT V
O
3 MAXIMUM LOAD CURRENT
Figure 13. Figure 14.
DETAILED DESCRIPTION
The TPS6514x series consists of a main boost converter operating with a fixed switching frequency of 1.6 MHz
to allow for small external components. The boost converter output voltage V
O
1 is also the input voltage,
connected via the pin SUP, for the positive and negative charge pump. The linear regulator controller is
independent from this system with its own enable pin. This allows the linear regulator controller to continue to
operate while the other supply rails are disabled or in shutdown due to a fault condition on one of their outputs.
Refer to the functional block diagram for more information.
Main Boost Converter
The main boost converter operates with PWM and a fixed switching frequency of 1.6 MHz. The converter uses a
unique fast response, voltage mode controller scheme with input voltage feedforward. This achieves excellent
line and load regulation (0.2% A load regulation typical) and allows the use of small external components. To add
higher flexibility to the selection of external component values, the device uses external loop compensation.
Although the boost converter looks like a nonsynchronous boost converter topology operating in discontinuous
mode at light load, the TPS6514x series maintains continuous conduction even at light load currents. This is
accoplished using the Virtual Synchronous Converter Technology for improved load transient response. This
architecture uses an external Schottky diode and an integrated MOSFET in parallel connected between SW and
SUP (see the functional block diagram). The integrated MOSFET Q2 allows the inductor current to become
negative at light load conditions. For this purpose, a small integrated P-channel MOSFET with typically 10 Ω
r
DS(on)
is sufficient. When the inductor current is positive, the external Schottky diode with the lower forward
voltage conducts the current. This causes the converter to operate with a fixed frequency in continuous
conduction mode over the entire load current range. This avoids the ringing on the switch pin as seen with a
standard nonsynchronous boost converter and allows a simpler compensation for the boost converter.
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