Datasheet

TPS82670 , TPS82671 , TPS82672 , TPS82673 , TPS82674 , TPS82675
TPS82676 , TPS82677 , TPS826711 , TPS826721 , TPS826745 , TPS826765
SLVSAI0H –OCTOBER 2010–REVISED OCTOBER 2014 www.ti.com
9.4 Device Functional Modes
9.4.1 Enable
The TPS8267x device starts operation when EN is set high and starts up with the soft start as previously
described. For proper operation, the EN pin must be terminated and must not be left floating.
Pulling the EN pin low forces the device into shutdown. In this mode, all internal circuits are turned off and the
V
IN
current reduces to the device leakage current, which is typically a few hundred nanoamps.
The TPS8267x device can actively discharge the output capacitor when it turns off. The integrated discharge
resistor has a typical resistance of 100 Ω. The required time to ramp down the output voltage depends on the
load current and the capacitance present at the output node.
9.4.2 Soft Start
The TPS8267x has an internal soft-start circuit that limits the in-rush current during start-up. This circuit limits
input voltage drop when a battery or a high-impedance power source is connected to the input of the MicroSiP™
DC/DC converter.
The soft-start system progressively increases the switching on-time from a minimum pulse-width of 35ns as a
function of the output voltage. This mode of operation continues for approximately 100μs after the enable. If the
output voltage does not reach its target value within the soft-start time, the soft-start transitions to a second mode
of operation.
If the output voltage rises above approximately 0.5V, the converter increases the input current limit and thus
enables the power supply to come up properly. The start-up time mainly depends on the capacitance present at
the output node and the load current.
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Product Folder Links: TPS82670 TPS82671 TPS82672 TPS82673 TPS82674 TPS82675 TPS82676 TPS82677
TPS826711 TPS826721 TPS826745 TPS826765