REG71050 Datasheet, PDF (8/32 Pages) Texas Instruments – Buck-Boost Charge Pump

REG71050, REG71055, REG710
SBAS221H – DECEMBER 2001 – REVISED OCTOBER 2015
8.2 Functional Block Diagram
V_IN
5
C_IN
2.2mF
C_PUMP
0.22mF
4
6
REG710
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3
Enable
Control
&
1
V_OUT
C_OUT
2.2mF
Thermal
2 GND
8.3 Feature Description
8.3.1 Shutdown Mode
The EN pin enables the IC when pulled high and places it into energy-saving shutdown mode when pulled low.
When in shutdown mode, the output is disconnected from the input and the quiescent current is reduced to 0.01
μA typical. This shutdown mode functionality is only valid when V_IN is above the minimum recommended
operating voltage. The EN pin cannot be left floating and must be actively terminated either high or low.
8.3.2 Protection
The regulator includes thermal shutdown circuitry protecting the device from damage caused by overload
conditions. The thermal protection circuitry disables the output when the junction temperature reaches
approximately 160°C, allowing the device to cool. When the junction temperature cools to approximately 140°C,
the output circuitry is automatically reenabled. Continuously operating the regulator into thermal shutdown can
degrade reliability. The regulator also provides current limit to protect itself and the load.
8.4 Device Functional Modes
8.4.1 Peak Current Reduction
In normal operation, the charging of the pump and the output capacitors usually leads to relatively high peak
input currents which can be much higher than the average load current. The regulator incorporates circuitry to
limit the input peak current, lowering the total EMI emission and lowering the output voltage ripple and the input
current ripple. The Input capacitor (C_IN) supplies most of the charge required by the input current peaks.
8.4.2 Efficiency
The efficiency of the charge pump regulator varies with the output voltage version, the applied input voltage, the
load current, and the internal operation mode of the device.
The approximate efficiency is given by:
8
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