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Vo1 − Output Voltage − V

Vo3 = 18 V (Doubler Mode)

0

0.02

0.04

0.06

0.08

0.10

0.12

9

10

11

12

13

14

15

Vo1 − Output Voltage − V

Vo3 = 28 V (Tripler Mode)

DETAILED DESCRIPTION

Main Boost Converter

VCOM Buffer

Enable and Power On Sequencing (EN, ENR)

TPS65100, TPS65101

TPS65105

SLVS496C – SEPTEMBER 2003 – REVISED APRIL 2006

Figure 13.

Figure 14.

The TPS6510x series consists of a main boost converter operating with a fixed switching frequency of 1.6 MHz

connected via the pin SUP, for the positive and negative charge pumps and the bias supply for the VCOM

buffer. 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. See the functional block diagram for more information.

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 TPS6510x 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

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.

VCOMIN is the input of the VCOM buffer. If the VCOM buffer is not required for certain applications, it is

possible to shut down the VCOM buffer by statically connecting VCOMIN to ground, reducing the overall

VCOMIN cannot be pulled dynamically to ground during operation.

The device has two enable pins. These pins should be terminated and not left floating to prevent unpredictable

operation. Pulling the enable pin (EN) high enables the device and starts the power on sequencing with the main

VCOMIN pin is held low, the VCOM buffer remains disabled. The linear regulator has an independent enable pin

(ENR). Pulling this pin low disables the regulator, and pulling this pin high enables this regulator.

If the enable pin EN is pulled high, the device starts its power on sequencing. The main boost converter starts

up first with its soft start. If the output voltage has reached 91.25% of its output voltage, the negative charge

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