Document
RT6296F
2A, 17V Current Mode Synchronous Step-Down Converter
General Description
The RT6296F is a high-efficiency, 2A current mode synchronous step-down DC-DC converter with a wide input voltage range from 4.5V to 17V. The device integrates 100m high-side and 40m low-side MOSFETs to achieve high efficiency conversion. The current mode control architecture supports fast transient response and internal compensation. The RT6296F provides power good pin to be an output voltage ready indicator. A cycle-by-cycle current limit function provides protection against shorted output. The RT6296F provides complete protection functions such as input under-voltage lockout, output under-voltage protection, over-current protection, and thermal shutdown. The PWM frequency is adjustable by the EN/SYNC pin. The RT6296F is available in the TSOT-23-8 (FC) package.
Ordering Information
RT6296F
Package Type J8F : TSOT-23-8 (FC)
Lead Plating System G : Green (Halogen Free and Pb Free)
Features
4.5V to 17V Input Voltage Range 2A Output Current Internal N-Channel MOSFETs Current Mode Control Fixed Switching Frequency : 500kHz Synchronous to External Clock : 200kHz to 2MHz Cycle-by-Cycle Current Limit Internal Soft-Start Function Power Saving Mode at Light Load Power Good Indicator Input Under-Voltage Lockout Output Under-Voltage Protection Thermal Shutdown RoHS Compliant and Halogen Free
Applications
Industrial and Commercial Low Power Systems Computer Peripherals LCD Monitors and TVs Set-top Boxes
Note :
Richtek products are : RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes.
Marking Information
0B=DNN
0B= : Product Code DNN : Date Code
Simplified Application Circuit
VIN Enable
C1 C2 R3
RT6296F VIN BOOT
C3
SW
EN/SYNC
PVCC
R5 FB
PG GND
L1 R1
R2
VOUT C4
Copyright © 2018 Richtek Technology Corporation. All rights reserved.
DS6296F-03 May 2018
is a registered trademark of Richtek Technology Corporation.
www.richtek.com 1
RT6296F
Pin Configuration
(TOP VIEW)
FB PVCC EN/SYNC BOOT
87 6 5 2 34
PG VIN SW GND
TSOT-23-8 (FC)
Functional Pin Description
Pin No. 1
2 3
Pin Name PG
VIN SW
Pin Function
Power good output. This pin is an open drain which can be connected to PVCC by a resistor. If output voltage achieve 90% of the normal voltage, the PG pin will go high after 400s delay.
Power input. Support 4.5V to17V Input Voltage. Must bypass with a ceramic capacitor at this pin.
Switch node. Connect to external L-C filter.
4 GND
System ground.
5 BOOT
Bootstrap supply for high-side gate driver. Connect a 0.1F ceramic capacitor between the BOOT and SW pins.
Enable control input. High = Enable. Apply an external clock to adjust the
6
EN/SYNC
switching frequency. If using pull high resistor connected to VIN, the
recommended value range is 60k to 300k.
7 PVCC
5V Bias supply output. Connect a minimum of 0.1F capacitor to ground.
8 FB
Feedback voltage input. The pin is used to set the output voltage of the converter to regulate to the desired voltage via a resistive divider. Feedback reference = 0.807V.
Copyright © 2018 Richtek Technology Corporation. All rights reserved.
www.richtek.com 2
is a registered trademark of Richtek Technology Corporation.
DS6296F-03 May 2018
Functional Block Diagram
PG PVCC
VIN
RT6296F
EN/SYNC
1.4V
Shutdown Comparator -
+
0.4V
+ - UV Comparator 1pF
50pF 400k
FB 0.807V + EA
Internal SS +
UVLO
Logic & Protection
Control
Oscillator
Internal Regulator
Current Sense
BOOT UVLO
Power Stage & Deadtime Control
HS Switch Current
Comparator
Slope Compensation
LS Switch Current
Comparator
Current Sense
BOOT SW
GND
Operation
Power Saving Mode
The RT6296F automatically enters into power saving mode (PSM) at light load to improve efficiency. In PSM, the RT6296F disable the internal CLK when VFB is above the VREF x 1.005 (typ.). In other words, the device automatically skip the PWM pulse at light load. While VFB falls below the VREF x 1.005, the RT6296F enables the internal CLK again and hence the new switching cycle is activated. When the internal switches are activated, for each cycle the device detects the peak inductor current (IL_PEAK) and keeps high-side switch on until the IL reaches its minimum peak current level (as shown in Figure 1). When low-side switch is turn-on, the zero-current detection is also activated to prevent that IL becomes negative and enables the higher efficiency at light load. During the period that both switches are off, the device turns off the most of the internal circuit to reduce the quiescent power consumption further.
With lower output loading, the non-switching period is longer, so the effective switching frequency becomes lower to reduce the switching loss and switch driving loss.
MPC IL
SW
Figure 1. Minimum Peak Current at PSM
Power Good Indicatio.