Si9169DB
Vishay Siliconix
Document Number: 71089
08-Jan-02 www.vishay.com
1
Si9169 Demonstration Board
FEATURES
DVoltage Mode Control
DFully Integrated MOSFET Switches
D1-A Load Capability
D2.7- to 6-V Input Voltage Range for VDD and VS
DProgrammable PWM/PSM Control
DUp to 2-MHz Switching Frequency in PWM
DSynchronous Rectification in PWM
DLess than 200-mA IDD in PSM
DIntegrated UVLO and POR
DIntegrated Soft-Start
DSynchronization
DShutdown Current t1 mA
DWide Bandwidth Feedback Amplifier
DSingle-Cell Li+ and 3-Cell NiCd or NiMH Operation
DESCRIPTION
The Si9169 is the higher power version of Si9165, with 1-A
output current capability compared to 600 mA for Si9165.
The Si9169 controller offers one of the most compact
synchronous buck or boost converter with 2.7- to 6-V input
voltage. The integrated MOSFETs and 2-MHz operating
frequency help shrinking the converter size dramatically.
There are two different version of demo boards (DB), buck and
boost converters, because the Si9169 can be easily
configured to buck or boost modes. The demo board has been
configured to generate 2.7-V regulated output for buck DB
while for boost DB is 3.6 V. The output voltage set point can be
easily adjusted by changing the value of R2(See Figure 1)
using the formula
(1)
R2+R1
VOUT
VREF –1
The typical value of VREF is 1.3 V. It is recommended not to
change R1since that would alter the control loop
compensation.
The PWM/PSM pin can be used to program the controller to
operate in PWM or PSM mode. PWM is normal pulse width
modulation to keep output regulated through out the load
range, while the PSM mode offers better efficiency at light load
to conserve power by skipping switching pulses. Notice the
PSM only gain efficiency advantage at light load and can only
deliver certain load current (about 150 mA) before output
drops out of regulation.
Included in this document are schematics (Figure 1 and
Figure 2), demo board sample waveform (Figure 3 through 6),
PCB layout (Figure 7 through 12), and Bill Of Material (Table 1
and 2).
The demonstration board layout is available in Gerber file format. Please contact your Vishay Siliconix sales representative or
distributor for a copy.
ORDERING INFORMATION: PART NUMBER Si9169DBĆK (BUCK CONVERTER)
Si9169DBĆS (BOOST CONVERTER)
TEST SETUP AND OPERATION
1. Visually inspect demo board and make sure that Jumper 1
is set to Enable and Jumper 2 is set to PWM.
2. Attach an electronic load set to either resistive or current
mode to the output pins (P3 and P4) on the demo board.
Set the load current to 200 mA or equivalent resistor value.
After the converter is powered up, output load current can
be adjusted.
3. Attach a dc power supply, with at least 3-A current
capability, to the input pins (P1 and P2) on the demo board.
The input voltage can be adjusted between 2.7 and 3.6 V
for boost DB or 2.7 to 6 V for buck DB.
4. Put an oscilloscope ground on the input ground, and the
Ch1 probe on the output and connect Ch2 probe on pin 20
of Si9169 (COIL pin). The waveform for buck and boost DB
should appear approximately as shown in Figure 3 and 4,
respectively.
5. To test your DB in PSM, adjust the load to 20 mA. Then
change Jumper 2 setting to PSM. Notice the reduction of
the input current. With the same probe setup mentioned
above, the waveform for buck and boost DB should appear
approximately as shown in Figure 5 and 6, respectively.
