CS51414GD8G ON Semiconductor, CS51414GD8G Datasheet - Page 13

• Manufacturer Part Number: CS51414GD8G
• Description: IC REG BUCK BIAS 1.5A 8-SOIC
• Manufacturer: ON Semiconductor
• Type: Step-Down (Buck)r

Specifications of CS51414GD8G

• Internal Switch(s): Yes
• Synchronous Rectifier: No
• Number Of Outputs: 1
• Current - Output: 1.5A
• Frequency - Switching: 520kHz
• Voltage - Input: 4.5 ~ 40 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Output Current: 1.5 A
• Input Voltage: 4.5 V to 40 V
• Switching Frequency: 520 KHz
• Operating Temperature Range: 0 C to + 70 C
• Mounting Style: SMD/SMT
• Duty Cycle (max): 90 %
• Primary Input Voltage: 40V
• No. Of Outputs: 1
• No. Of Pins: 8
• Voltage Regulator Type: Buck DC/DC Converter
• Supply Voltage Min: 4.5V
• Rohs Compliant: Yes
• Leaded Process Compatible: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Output: -
• Power - Output: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

turns P1 on and current is routed to the internal bias circuitry
from the BIAS pin.
The input voltage range for V
voltage range for BIAS is 3.3 V to 6 V. The quiescent current
specification is 3 mA (min), 4 mA (typ), and 6.25 mA (max).
quiescent current number of 4 mA, the power would be:
regulator at 5 V instead of the output voltage. The BIAS pin
would normally be connected to the output voltage, but
adding an added switching regulator efficiency number here
would cloud this example. Now the internal BIAS circuitry
is being powered via 5 V. The resulting on chip power being
dissipated is:
maximum battery input voltage of 40 V, the maximum
quiescent current of 6.25 mA, and the lowest allowed BIAS
voltage for proper operation of 3.3 V;
Minimum Load Requirement
required for this regulator due to the predriver current
feeding the output. Placing a resistor equal to V
12 mA should prevent any voltage overshoot at light load
conditions. Alternatively, the feedback resistors can be
valued properly to consume 12 mA current.
Input Capacitor
current with an amplitude equal to the load current. This
pulsed current and the ESR of the input capacitors determine
the V
ripple, low ESR is a critical requirement for the input
capacitor selection. The pulsed input current possesses a
significant AC component, which is absorbed by the input
capacitors.
using:
where:
Here is an example of the power savings:
Using a typical battery voltage of 14 V and the typical
We’ll assume the BIAS pin is connected to an external
The power savings is 35 mW.
Now, to demonstrate more notable savings using the
Powered from V
Powered from the BIAS pin:
The power savings is 229 mW.
As pointed out in the previous section, a minimum load is
In a buck converter, the input capacitor witnesses pulsed
The RMS current of the input capacitor can be calculated
D = switching duty cycle which is equal to V
I
O
= load current.
IN
ripple voltage, which is shown in Figure 19. For V
P + V
P + V
COMPONENT SELECTION
P + 40
P + 3.3
I RMS + I O D(1 * D)
in
:
I + 14
I + 5
6.25e−3 + 250 mW
6.25e−3 + 21 mW
in
4e−3 + 21 mW
4e−3 + 56 mW
is 4.5 V to 40 V. The input
O
O
divided by
/V
IN
http://onsemi.com
.
IN
13
with the constant given by Figure 20 at each duty cycle. It is
a common practice to select the input capacitor with an RMS
current rating more than half the maximum load current. If
multiple capacitors are paralleled, the RMS current for each
capacitor should be the total current divided by the number
of capacitors.
design’s constraint and emphasis. The aluminum
electrolytic capacitors are widely available at lowest cost.
Their ESR and Equivalent Series Inductor (ESL) are
relatively high. Multiple capacitors are usually paralleled to
achieve lower ESR. In addition, electrolytic capacitors
usually need to be paralleled with a ceramic capacitor for
filtering high frequency noises. The OS−CON are solid
aluminum electrolytic capacitors, and therefore has a much
lower ESR. Recently, the price of the OS−CON capacitors
has dropped significantly so that it is now feasible to use
them for some low cost designs. Electrolytic capacitors are
Calculated by Multiplying Y Value with Maximum Load
Figure 19. Input Voltage Ripple in a Buck Converter
To calculate the RMS current, multiply the load current
Selecting the capacitor type is determined by each
0.6
0.5
0.3
0.2
0.1
0.4
Figure 20. Input Capacitor RMS Current can be
0
0
0.2
Current at any Duty Cycle
0.4
DUTY CYCLE
0.6
0.8
1.0