Wafer-Level Packages for LDOs and Step-Down DC-DCs
Torex's ultra-small WLP (Wafer Level Packages) are now available for the XC6602 series of LDO regulators and the XC9235/36/37 series of step-down dc-dc converters.
The WLP packages use metal wiring instead of wire bonding, meaning a lower On-resistance can be achieved. This can increase the efficiency of the XC9235/36/37 dc-dc converters by 2-3% during heavy loads. The characteristic of dropout voltage and Vout-Iout for the XC6602 LDO are also improved compared with the usual packages.
The XC6602 series are high-speed LDO regulators with an ultra-low ON resistance that can operate from an input voltage of 0.5V at a maximum output current of 1A maximum, and are designed for applications that require efficient output of a large current at low voltages.
The XC9235/XC9236/XC9237 series are synchronous step-down dc-dc converters with an internal 0.42Ω Pch MOS driver Tr. and an internal 0.52Ω Nch MOS switch Tr. These converters are able to provide a stable power supply with high efficiency at a maximum output of 600mA.
Torex' s WLP (WL-CSP) is a Chip Scale Package. Using the WLP package, we are deploying a product line based on the concepts "ultra-small", "ultra-thin", and "conductivity". The process consists of (1) circuit face polyimide protection, (2) rewiring, (3) rewiring polyimide protection, and (4) solder ball mounting (Fig. 1).
(click on image to enlarge)
There is no protection on the silicon face and laser marking is performed directly, for a simple structure that enables the features "small", "thin", and "low cost". The distance between the circuit face and parts that connect to the board (solder balls) is short, allowing higher heat dissipation and easier heat treatment design than other devices of similar size (refer to Fig. 2, Structural Drawing).
The XC6602 series are 1A high-speed LDO regulators that support a low input voltage (from 0.5V). Bias voltage drive is used to enable operation at a low ON resistance even when the output voltage is low.
In addition, voltage drops on the input-output line due to load fluctuations are reduced, and operation at a lower dropout voltage than previous products is possible. A stable output voltage can be supplied even when a large current is required.
Since WLP-5-02 uses metal wiring instead of wire bonding, it can achieve a lower On resistance. As a result, the characteristic of dropout voltage and Vout-Iout are improved compared with the usual packages.
Since WLP-5-03 package use metal wiring instead of wire bonding, the WLP-5-03 package enables to achieve 0.03Ω to 0.05Ω lower On resistance than other packages, which results in increasing the efficiency by 2 to 3% during heavy loads.
Pch driver ON resistance (depends on VIN)
