SP6680EB Datasheet, PDF (2/5 Pages) Sipex Corporation – Evaluation Board Manual

The SP6680 Evaluation Board provides convenient test points to connect the input to
Power Supply or Li-Ion Battery. The Input and Output connections are made with
raised female pin receptacles which can accommodate easy-hook connection leads for
power and meter connections, as well as scope probe hooks and grounds for waveform
measurements.
USING THE EVALUATION BOARD
1) Powering Up the SP6680 Circuit
The SP6680 Evaluation Board can be powered from a single Li-Ion battery or a +2.7 to
+6.3V power supply. Connect with short leads directly to the “Vin” and “Gnd” posts.
Note the SP6680 will remain in “shutdown” until a Clock input is applied to the “CLK”
input post.
2) Enabling the SP6680 Output with CLK Input
The SP6680 output will typically be in low current “shutdown” mode until a Clock Input is
applied to the “CLK” post. This input typically is a CMOS level 32.768kHz clock derived
from a real-time clock crystal, but any stable square wave function generator with a
V_IL<0.4V and V_IH>1.3V will do. You can now measure the SP6680 pre-regulated output
of 5.2V to 6.3V with a voltmeter or scope across the “Vout” and “Gnd” posts.
3) Controlling the Pump Frequency
The SP6680 has 3 frequency modes controlled by the presence of a 32.768kHz Clock
at “CLK” input, and levels at the digital inputs at posts “CD4” or “CX8”. Basically, the
SP6680 will pump at the 32.768kHz Clock input frequency unless a High level is
present at CD4 or CX8, as illustrated in the Pump Frequency Control table below.
Apply Logic High to “CD4” post and the SP6680 will pump at ¼ frequency or 8.192kHz.
Or, apply a Logic High to “CX8” post and the SP6680 will pump at 8 times the Clock
frequency or 262.14kHz. Observe the pump frequency by applying a scope probe to
CF2P post.
TABLE1: PUMP FREQUENCY CONTROL
CLK pin
not present
32.768kHz
32.768kHz
32.768kHz
32.768kHz
CD4
X
Low
Low
High
High
CX8
X
Low
High
Low
High
Fpump Frequency
0
32.768kHz
262.14kHz
8.192kHz
262.14kHz
Maximum Output
0
20mA
60mA
2mA
60mA
As you can see from the table, as pump frequency increases, the capability of the
SP6680 maximum output current increases (and quiescent current will rise). See the
SP6680 datasheet specification table to compare how the Output Resistance, Output
Voltage and Power Efficiency parameters vary with Pump Frequency.
4) Dynamic Charge Pump Action
The charge pump configuration dynamically changes to optimize efficiency. At low input
voltages the charge pump doubles the input, while at higher inputs the output is 1.5
times the input. You can observe this action by monitoring how the output voltage
Rev. 6/27/01
SP66680 Evaluation Board Manual
2
© Copyright 2001 Sipex Corporation