MAX1565 Datasheet, PDF (23/26 Pages) Maxim Integrated Products – Small, High-Efficiency, Five-Channel Digital Still Camera Power Supply

Small, High-Efficiency, Five-Channel
Digital Still Camera Power Supply
TO V_BATT
L1
10µH
1µF
D2
C2
1µF
AUX_
FB_
PWM
OUTSU
DL_
Q1
C1
1µF
D1
R1
1MΩ
V_OUT+
+15V
20mA
R2
90.9kΩ
D3
V_OUT-
-15V
C3 _10mA
1µF
MAX1565
(PARTIAL)
Figure 9. ±15V Output Using a Boost with Charge-Pump
Inversion
When the MOSFET turns on, C1 discharges through
D3, thereby charging C3 to V_OUT- minus the drop
across D3 to create roughly the same voltage as
V_OUT+ at V_OUT- but with inverted polarity.
If different magnitudes are required for the positive and
negative voltages, a linear regulator can be used at
one of the outputs to achieve the desired voltages. One
such connection is shown in Figure 10. This circuit is
somewhat unique in that a positive output linear regula-
tor is able to regulate the negative output. It does this
by controlling the charge to the flying capacitor rather
than directly regulating at the output.
Adding a MAX1801 Slave
The MAX1801 is a 6-pin SOT slave DC-to-DC controller
that can be connected to generate additional output
voltages. It does not generate its own reference or
oscillator. Instead, it uses the reference and oscillator
of the MAX1565 (Figure 11). The MAX1801 controller
operation and design are similar to that of a MAX1565
AUX controller. All comments in the Auxiliary Controller
Component Selection section also apply to add-on
MAX1801 slave controllers. For more details, refer to
the MAX1801 data sheet.
10µH
TO V_BATT
1µF
1µF
AUX_
FB_
PWM
OUTSU
DL_
Q1 1µF
+15V
20mA
1MΩ
90.9kΩ
1µF
MAX1565
(PARTIAL)
1µF
IN
SHDN
GND
-7.5V
20mA
110kΩ
549kΩ
OUT
FB_
+1.25V
MAX1616
Figure 10. +15V and -7.5V CCD Bias without Transformer
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