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TEA1532CT

GreenChip II SMPS control IC

NXP Semiconductors. 

NXP Semiconductors

TEA1532BT; TEA1532CT

GreenChip II SMPS control IC

The charging current Istartup(soft) will flow as long as the voltage on pin SENSE is

below approximately 0.5 V. If the voltage on pin SENSE exceeds 0.5 V, the soft start

current source will start limiting current Istartup(soft). At Vstartup, the Istartup(soft) current source

is completely switched off; see Figure 8.

Since the soft start current is supplied from pin DRAIN, the Rss value will not affect VCC

current during start-up.

Iss

0.5 V

start-up

6 SENSE Rss

Fig 8. Soft start-up

Vocp

Css

Rsense

mgu237

7.13 Control pin protection

If the pin CTRL becomes open-circuit or is disconnected, a fault condition is assumed and

the converter will stop switching immediately. Operation recommences when the fault

condition is removed.

7.14 PROTECT and timing input

The PROTECT input (pin 3) is a multi-purpose (high-impedance) input, which can be used

to switch off the IC and create a relatively long timing function. As soon as the voltage on

this pin rises above 2.5 V, switching stops immediately. For the timing function, a current of

typically 50 µA flows out of pin PROTECT and charges an external capacitor until the

activation level of 2.5 V is reached. This current source is only activated when the

converter is not in regulation, which is detected by the voltage on pin CTRL

(VCTRL < 0.63 V). A (small) discharge current is also implemented to ensure that the

capacitor is not charged, for example, by spikes. A MOSFET switch is added to discharge

the external capacitor and ensure a defined start situation. For the TEA1532CT, the

voltage on pin CTRL determines whether the IC enters latched protection mode, or safe

restart protection mode:

• When the voltage on pin CTRL is below 0.63 V, the IC is assumed to be out of

regulation (e.g. the control loop is open). In this case activating pin PROTECT

(VPROTECT > 2.5 V) will cause the converter to stop switching. Once VCC drops below

Vth(UVLO), capacitor CVCC will be recharged and the supply will restart. This cycle will

be repeated until the fault condition is removed (safe restart mode).

• When the voltage on pin CTRL is above 0.63 V, the output is assumed to be in

regulation. In this case activating pin PROTECT (VPROTECT > 2.5 V), by external

means, will activate the latch protection of the IC: The voltage on pin VCC will cycle

between Vstartup and Vth(UVLO), but the IC will not start switching again until the latch

TEA1532BT_TEA1532CT_1

Product data sheet

Rev. 01 — 18 January 2007

© NXP B.V. 2007. All rights reserved.

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