ncn6004a ON Semiconductor, ncn6004a Datasheet - Page 24

• Manufacturer Part Number: ncn6004a
• Description: Dual Sam/sim Interface Integrated Circuit
• Manufacturer: ON Semiconductor

C1 carry relative high peak current, low ESR devices must
be used to prevent the system from poor output voltage
ripple and low efficiency. Using ceramic capacitors, X5R or
X7R type, are recommended, splitting the 10 mF in two
separate parts when there is a relative long distance between
the card is extracted from the socket, the active pull down Q5
rapidly discharges the output reservoir capacitor, making
sure the output voltage is below 0.40 V when the card slides
across the contacts.
NCN6004A characterization, the best comprise, at time of
printing
4.7 mF/10 V/ceramic/X7R capacitor in parallel to achieve
the CRD_VCC filtering. The ESR will not extend 50 mW
Table 6. Ceramic/Electrolytic Capacitors Comparison
MURATA
MURATA
VISHAY
VISHAY
Miscellaneous
Since the output inductor L1 and the reservoir capacitor
When the CRD_VCC is programmed to zero volt, or when
Based on the experiments carried out during the
Manufacturer
CRD_VCC
Q1 / Q4
Q2 / Q3
Q5/Q6
IL
this
Ton Toff
document,
CRD_VCC Voltage Regulated
Tantalum/594C/593C
Electrolytic Low Cost
CERAMIC/GRM225
CERAMIC/GRM225
Electrolytic/94SV
Charge CRD_VCC
Type/Series
is
Figure 16. Theoretical DC/DC Operating
to
use
Format
http://onsemi.com
(Time is not to scale)
CRD_VCC Charged
0805
0805
1206
1812
1812
two
NCN6004A
24
Ipeak
the CRD_VCC_x output pin and the card VCC input. On the
other hand, the inductor shall have an ESR below 1.0 W to
achieve the high efficiency over the full temperature range.
However, inductor with 2.0 W ESR can be used when a slight
decrease of the efficiency is acceptable at system level.
over the temperature range and the combination of standard
parts provide an acceptable –20% to +20% tolerance,
together with a low cost. Table 6 shows a quick comparison
between the most common type of capacitors. Obviously,
the capacitor must be SMD type to achieve the extremely
low ESR and ESL necessary for this application.
NCN6004A demo board running with X7R ceramic
capacitors.
Figure 17 illustrates the CRD_VCC ripple observed in the
4.7 mF/6.3 V
10 mF/6.3 V
Max Value
10 mF/16 V
10 mF/10 V
10 mF/10 V
Next CRD_VCC Charge
−20% /+20%
−20% /+20%
−20%/+20%
−35%/+50%
Tolerance
Typ. Z @ 500 kHz
450 mW
400 mW
30 mW
30 mW
2.0 W