Many engineers in the choice of BOOST type DC-DC chip found that even if the chip with the enable function, still can not turn off the system, the output voltage or follow the input voltage exists, at this time the consumption current follows the load changes, in this state will not only continue to consume power, but also the risk of damage to the post-stage circuit.
Why can’t some DC-DC booster chips be turned off completely?
Above is the circuit topology of the BOOST circuit, the integrated BOOST controller is actually just the integrated switch tube of the topology circuit, and adds some other functions.
It can be seen from the above figure that the traditional DC-DC booster chip has limitations. Even if the controller is turned off by the enable pin of the controller, only the boost function of the chip itself is turned off, the input voltage can still be VOUT to the output end through the inductor L and the diode. At this time, the VOUT voltage follows the VIN voltage, and the system consumption changes with the load.
From the above, we know that the “true shutdown” is mainly defined to solve the problem that the traditional DC-DC booster IC does not really disconnect the output when it is turned off; The “true off” directing energy can not only turn off the internal circuit and power tube of the chip, but also really disconnect the input and output load paths. Effectively reduce system shutdown power consumption, reduce the risk of overload and short circuit, reduce system cost, and extend battery life.
The SSP8099 has a true shutdown function to boost DC-DC
Product overview
The SSP8099 is a synchronous boost converter. Suitable for alkaline batteries, nickel-metal hydride rechargeable batteries, lithium-manganese batteries or lithium-ion rechargeable battery powered products, for these products, high efficiency under light load conditions is the key to achieve battery longevity.
The SSP8099 can support up to 300mA output current conversion from 3.3V to 5V and achieve 90% efficiency at 200mA loads.
The SSP8099 also offers buck and pass through modes for different applications. In buck mode, even if the input voltage is higher than the output voltage (VOUT < VIN < VOUT + 0.3V), the output voltage can still be adjusted to the target value. In through mode, the output voltage follows the input voltage. When VIN>VOUT + 0.3V, the SSP8099 exits the buck mode and enters the direct mode.
The SSP8099 supports a true shutdown function in the off state, disconnecting the load from the input power to reduce current consumption.
Features
- Operating Input Voltage Range: 0.9V to 5.2V
- Ultra Low Quiescent Current Low shutdown mode current：<1μA ; Ultra Low IQ into VIN Pin：<2μA
- 1.0MHz Fixed Frequency Operation
- Adjustable Output Voltage from 2.5V to 5.2V
- Fixed Output Voltage Versions Available
- Power-Save Mode for Improved Efficiency at Low Output Power
- Regulated Output Voltage in Down Mode
- True Disconnection During Shutdown
- Up to 90% Efficiency from 10mA to 300mA Load
- -40℃ to +85℃ Operating Ambient Temperature Range
- Available in Green WLCSP-1.22×0.83-6B and TDFN-2×2-6AL Packages
Pin Configurations
Typical Application Circuits
(Adjustable output voltage version)
(Fixed output voltage version)
Comparison of similar products
The equipment used in this test are: Puyuan brand MSO5204 digital oscilloscope and multimeter.
(Figure 1 SSP8099 )
(Figure 2 SSP8711)
Figure 1 shows the output voltage waveform test diagram of the “true shutdown” booster chip SSP8099. It can be seen from the oscilloscope that when the EN is pulled down, the output of the chip will also be disconnected, achieving the “true shutdown function”.
Figure 2 shows the output voltage waveform test diagram of the traditional booster chip SSP8711. It can be seen from the oscilloscope that when EN is pulled down, the output of the chip is not completely turned off, only the boost function of the chip is turned off, and the output voltage of the chip still exists at this time, and the output voltage is almost equal to the input voltage.
