S-8540 SII [Seiko Instruments Inc], S-8540 Datasheet - Page 19

• Manufacturer Part Number: S-8540
• Description: STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
• Manufacturer: SII [Seiko Instruments Inc]

Rev.3.2
Precautions
When the input voltage is 9 to 10 V, V
When it is difficult to make one-point grounding, use two grounds: one for V
Install the external capacitors, diode, coil, and other peripheral components as close to the IC as possible,
and make a one-point grounding.
other for V
current flows at the time of a power supply injection. Because these largely depend on the inductor, the
capacitor and impedance of power supply used, fully check them using an actually mounted model.
If the input voltage is high and output current is low, pulses with a low duty ratio may appear, and then the
0% duty ratio continues for several clocks.
frequency modulation (PFM) mode, but the ripple voltage hardly increases.
may be turned on.
If input power supply voltage is 10.0 V or higher, the circuit operation is unstable and the IC may be
damaged.
The input voltage must be in the standard range (2.5 to 10.0 V).
The current limit circuit of the IC limits current by detecting a voltage difference of external resistor R
In choosing the components, make sure that overcurrent will not surpass the allowable dissipation of the
switching transistor and the inductor.
Make sure that dissipation of the switching transistor will not surpass the allowable power dissipation of the
package (especially at high temperature).
electrostatic protection circuit.
Seiko Instruments Inc. shall bear no responsibility for any patent infringement by a product that includes an
IC manufactured by Seiko Instruments Inc. in relation to the method of using the IC in that product, the
product specifications, or the destination country.
Characteristics ripple voltage and spike noise occur in IC containing switching regulators. Moreover rush
If the input power supply voltage is lower than 1.0 V, the IC operation is unstable and the external switch
Do not apply an electrostatic discharge to this IC that exceeds the performance ratings of the built-in
STEP-DOWN, 600 kHz PWM CONTROL or PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
_00
OUT
, V
CVREF
, and IC GND.
OUT
may vary largely according to the grounding method.
Seiko Instruments Inc.
In this case the operation changes to the pseudo pulse
IN
, C
IN
S-8540/8541 Series
, and SD GND, and the
SENSE
19
.