BD9740KN-E2 Rohm Semiconductor, BD9740KN-E2 Datasheet - Page 9

• Manufacturer Part Number: BD9740KN-E2
• Description: IC SWITCH REG W/FET 48UQFN
• Manufacturer: Rohm Semiconductor
• Series: -r
• Type: Step-Down (Buck), Step-Up (Boost), Inverting, PWMr

Specifications of BD9740KN-E2

• Internal Switch(s): Yes
• Synchronous Rectifier: Yes
• Number Of Outputs: 7
• Voltage - Output: -
• Current - Output: 30mA
• Frequency - Switching: 100kHz ~ 1.2MHz
• Voltage - Input: 1.5 V ~ 10 V
• Operating Temperature: -20°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-VFQFN
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

BD9739KN,BD9740KN
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10. Setting MAX DUTY
11. Soft start operation triggered by the DTC pin
12. Internal soft start operation
13. Setting the error amp feedback resistance
The DTC voltage is determined by the internal R1 and R2 resistance values. The DTC voltage can be changed by
connecting resistance values that are from 1 to 2 digits smaller than the internal R1 (30 k) and R2 (93 k) resistors, to
the RA and RB pins.
*The resistors connected to the RA and RB pins should be at least 5 k. Avoid shorting the VREGA and DTC pins.
*When VCC falls to 2.8 V or below, a protection circuit will operate to limit MAX DUTY in order to prevent the IC from
Soft start operation can be set by connecting a capacitor to the DTC pin. Setting the STBY pin to high will cause the
capacitor connected to the DTC pin to be charged by the internal pull-up resistor.
Startup will begin when this voltage reaches the minimum voltage of the CT pin's triangular waveform.
*Set the capacitance connected to each DTC pin to 10 μF or less.
Soft start times are set internally for CH4, CH6, and CH7 (BD9739KN); and CH2 to CH4 (BD9740KN).
BD9739KN
BD9740KN
(1) Feedback resistance order (BD9739KN, BD9740KN)
(2) Setting the inverted channel (BD9739KN, BD9740KN)
malfunctioning when VREGA (the internal circuit power supply) drops.
Error amp differential input is formed by a PNP transistor, with the base current of this input flowing into the lower
voltage divider resistor. In the worst case, this current may reach 0.2 μA. For this reason, when the resistance of the
lower resistor is increased, the base current may cause an error in the output voltage. For example, resistance values
of 40 k, 20 k, and 10 k result in errors of 1%, 0.5%, and 0.25%, respectively. Refer to these values when setting
the resistance value.
For the BD9739KN, connect the CH5 error amp reference voltage (INV5) to the ground.
For the BD9740KN, the CH6 error amp reference voltage is grounded internally.
*It is recommended to use a 10 k resistor between VREF and CH5 output. Use a resistance value from 5 k to 20 k.
CH4, 6, 7: 2.7 ms
CH2 to CH4: 3.6 ms
(Soft start operation of CH2 and CH3 is delayed until CH4 reaches approximately 80%.)
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Technical Note
2010.09 - Rev.A