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SIP11206

Half-Bridge Controller with Primary MOSFET Drivers for Intermediate Bus Converters

Vishay Semiconductors 

SiP11206

Vishay Siliconix

due to some external reset condition the pre-regulator is in

low power standby mode and the internal bias network is

powered down. When VINDET is greater than VSDH but less

than VREF and VCC is forced to 12 V the pre-regulator shuts

off drawing only leakage current from VIN and quiescent

current from VCC. In this mode the controller output drivers

remains static (non-switching). When VINDET is above VREF

the controller is enabled and both drivers are switching at half

the oscillator frequency. If SiP11206 is shut down via this pin,

its restart will be by means of a soft-start cycle, as described

under "Soft Start" and "Hiccup-Mode Operation" above.

The input impedance to ground of this pin is typically

46K ± 30 % and must be taken into account at application

design. An external 10:1 resistor divider ratio of supply

voltage to VINDET pin is required in a typical application.

TYPICAL CHARACTERISTICS

10.2

10.0

9.8

9.6

9.4

9.2

9.0

8.8

8.6

8.4

8.2

- 40 - 15 10 35 60 85

Temperature (°C)

VREG vs. Temperature

3.35

110 135

3.30

3.25

VUVH

3.20

3.15

3.10

3.05

VUVL

3.00

- 40 - 15 10 35 60 85

Temperature (°C)

VUV vs. Temperature

110 135

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10

Primary High and Low Side MOSFET Drivers

The low-side MOSFET driver is powered directly from VCC of

the chip. The high-side MOSFET however requires the gate

voltage to be higher than VIN. This is achieved with a charge

pump capacitor CBST between BST and LX, and an external

diode to charge and bootstrap the initial charge up voltage

across CBST to VCC level. On the alternate oscillator cycle

the boost diode isolates BST from VIN and hence BST and

LX steps up to VIN + VCC and VIN, respectively. This

sequencing insures that DL will always turn on before DH

during start-up. The boost capacitor value must be chosen to

meet the application droop rate requirement.

External Frequency Synchronization

The oscillator frequency of this IC can be synchronized to an

external source with a simple circuit shown in "Circuit for

Frequency Synchronization" diagram. The synchronized

frequency should not exceed 1.4 times the set frequency,

and the synchronized frequency range should not exceed

the IC frequency range.

7.5

7.0

6.5

VIN = 75 V

6.0

5.5

5.0

4.5

- 40 - 15

8.0

10 35 60 85

Temperature (°C)

IVIN vs. Temperature

110 135

7.5

7.0

ICC

6.5

VCC = 12 V

6.0

5.5

5.0

IQ

4.5

4.0

- 40 - 15 10 35 60 85 110 135

Temperature (°C)

ICC and IQ vs. Temperature

Document Number: 69232

S-81795-Rev. C, 04-Aug-08

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