Application Note: AN_ SY6402
High Efficiency Bi-directional DC-DC Regulator With
High Current Over Voltage Protection Switch

Compact package: QFN3X4-19

SY6402 is designed to achieve energy storage and
release management for the applications of data backup
in Solid-State Driver and other backup power supplies.
The integrated bi-directional Dc-Dc regulator transfers
the energy between the system side and the energy
storage side with high efficiency. The quasi-fixed
frequency constant off time control is employed to
achieve stable operation and fast dynamic response.
Besides, a reverse blocking switch is integrated at the
input side to prevent from energy leaking when the
input power source is removed or inserted with inverse
polarity. The programmable input current limit
cooperates with the bi-directional Dc-Dc regulator to
achieve power path management for better dynamic
load response at the system side. Three different input
voltage OVP thresholds are selectable for the
applications with different kind of input power source.
SY6402 along with QFN3X4-19 package provides
compact PCB layout

• Low R
DS(ON) for internal switches
- Input Reverse Blocking Switch: 50 mΩ
- High-side and Low-side Switches of Bidirectional Dc-Dc Regulator: 60 mΩ /60 mΩ
- Disconnect Switch: 30 mΩ
• 2.7V-16V Input Voltage Range
• 36V Storage Voltage Rating
• Programmable Input Current Limit from 1A to 5A
• Selectable Over Voltage Protection: 3.3V, 5.0V,
and 12V
• Reverse Blocking at Input Side
• Programmable Soft-start Time
• Integrated High-efficiency Bi-directional Dc-Dc
Regulator: Boost Charging Mode and Buck
Discharging Mode Auto-alternating with
Programmable System Voltage
• Quasi-Fixed Frequency Constant OFF Time
Control for Stable Operation: 500kHz
• Programmable Boost Charging Current
• Programmable Storage Voltage
• Power Path Management
• Short-circuit Protection at Energy Storage Side
• Enable Control
• RoHS Compliant and Halogen Free
• Compact package: QFN3X4-19
Applications
• Solid-State Drivers
• Backup Power Supply