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DRV8809 Datasheet, PDF (29/44 Pages) Texas Instruments – COMBINATION MOTOR DRIVERS WITH DC-DC CONVERTERS
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DRV8809
DRV8810
www.ti.com ............................................................................................................................................................... SLVS854A – JULY 2008 – REVISED JULY 2008
Charge Pump
The charge-pump voltage-generator circuit utilizes external storage and bucket capacitors. It provides the
necessary voltage to drive the high-side switches for both DC-DC regulators and motor drivers. The
charge-pump circuit is driven at a frequency of 1.6 MHz (nom). Recommended bucket capacitance is 10 nF, 16
V (min), and storage capacitance is 0.1 µF, 60 V (min). The charge-pump storage capacitor, Cstage, should be
connected from the VCP output, pin 22, to VM.
For power-saving purposes in sleep mode, the charge pump is stopped when n_sleep = L and all three
regulators are turned OFF. When the part is powered up, the charge pump is started first after the C_select
capture, and 10 ms after the CP startup, the first regulator is started up.
FAULT CONDITION
0
0
0
0
0
Motor OCP
TSD
DC-DC Ch-A
OFF
ON
X
X
X
X
X
Table 15. Charge Pump
DC-DC Ch-B
OFF
X
ON
X
X
X
X
DC-DC Ch-C
OFF
X
X
ON
X
X
X
nSLEEP
0
X
X
X
1
1
X
CHARGE PUMP
OFF
ON
ON
ON
ON
ON
OFF
VM
Charge
pump
OSCD
(100 kHz)
OSCi
(6.4 MHz)
Vref
1.5 V
Overcurrent
sense
Control logic
and predriver
Current limit
OD_x
Output
FBx
voltage
Over
supervisor
current Protect
Disable
detect disable
(mask)
UVP OVP
(-30%) (+30%)
C_SELECT
Setup/
Extended Setup
register
Soft start,
Protection control, and
nORT assertion
Figure 21. DC-DC Converter
This is a switch-mode regulator with integrated switches, to provide a programmed output set by the feedback
terminal. The DC-DC converter has a fixed frequency variable duty cycle topology with a switching frequency of
100 kHz (nom). External filtering (inductor and capacitor) and external catch diode are required. The output
voltage is short-circuit protected. If the system has a high input voltage and a very light load on the output, the
converter may not provide energy to the inductor (skip) until the load line or the minimum voltage threshold is
reached.
Copyright © 2008, Texas Instruments Incorporated
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